Blood, lymph, tissue fluid. Blood in adults

The third physiological compound of hemoglobin is carbohemoglobin - a compound of hemoglobin with carbon dioxide. Thus, hemoglobin is involved in the transport carbon dioxide from tissues to lungs. Carbohemoglobin is found in venous blood.

When hemoglobin is exposed to strong oxidizing agents (berthollet salt, potassium permanganate, nitrobenzene, aniline, phenacetin, etc.), iron is oxidized and becomes trivalent. In this case, hemoglobin is converted into methemoglobin and acquires a brown color. Being a product of true oxidation of hemoglobin, the latter firmly retains oxygen and therefore cannot serve as its carrier. The formation of a significant amount of methemoglobin sharply worsens the respiratory functions of the blood. This can happen after the introduction of drugs with oxidizing properties into the body. Methemoglobin is a pathological compound of hemoglobin.

Hemoglobin very easily combines with carbon monoxide to form carboxyhemoglobin (HbCO). The chemical affinity of carbon monoxide for hemoglobin is approximately 200 times greater than that of oxygen. Therefore, it is enough to add a small amount of CO to the air to form a significant number of molecules of this compound. It is very strong, and hemoglobin, blocked by CO, cannot be an oxygen carrier. Therefore, carbon monoxide is very poisonous. When inhaling air containing 0.1% CO, severe consequences of oxygen starvation (vomiting, loss of consciousness) develop after 30-60 minutes. When the air contains 1% CO, death occurs within a few minutes. Affected people and animals must be taken out into clean air or allowed to breathe oxygen. Under the influence of high oxygen pressure, carboxyhemoglobin is slowly broken down.

When hydrochloric acid acts on hemoglobin, hemin is formed. In this compound, iron is in the oxidized trivalent form. To obtain it, a drop of dried blood is heated on a glass slide with crystals of table salt and 1-2 drops of glacial acetic acid. Brown orthorhombic crystals of hemin are examined under a microscope. Hemin crystals of different animal species differ in their shape. This is due to species differences in the structure of globin. This reaction, called the hemin test, can be used to detect traces of blood.

When viewing a diluted solution of oxyhemoglobin through a spectroscope, two characteristic dark absorption bands are visible in the yellow-green part of the spectrum, between the Fraunhofer lines D and E. Reduced hemoglobin is characterized by one wide absorption band in the yellow-green part of the spectrum. The spectrum of carboxyhemoglobin is very similar to that of oxyhemoglobin. They can be distinguished by the addition of a reducing agent. Carboxyhemoglobin and after that has two absorption bands. Methemoglobin has a characteristic spectrum: one narrow absorption band is on the left, on the border of the red and yellow parts of the spectrum, another narrow band on the border of the yellow and green zones, and a wide dark band in the green part.

The amount of hemoglobin is determined by the colorimetric method and expressed as a gram percent (g%), and then using the International System of Units (SI) conversion factor, which is equal to 10, the amount of hemoglobin is found in grams per liter (g/l). It depends on the type of animal. The content of red blood cells and hemoglobin is affected by age, gender, breed, altitude, work, feeding. Thus, newborn animals have a higher content of red blood cells and hemoglobin than adults; In males, the number of red blood cells is 5-10% higher than in females.

The number of erythrocytes in racehorses is greater than in draft horses, and reaches 10-10.5 million/µl of blood, or according to the SI system 10-10.5.1012 l, and in draft horses it is 7.4-7.6 million/µl

The decrease in oxygen pressure at high altitudes stimulates the formation of red blood cells. Therefore, in sheep and cows on mountain pastures the number of red blood cells and hemoglobin is increased. Intense physical activity produces the same effect. The amount of hemoglobin in the blood of trotters, equal to an average of 12.6 g% (126 g/l) before running, increases to 16-18 g% (160-180 g/l) after running. Deterioration of feeding leads to a decrease in the content of red blood cells and hemoglobin. The lack of microelements and vitamins (cyanocobalamin, folic acid, etc.) has a particularly large impact.

To determine the saturation of each red blood cell with hemoglobin, a color indicator or index I is used

Normally, the color index is 1. If it is less than 1, the hemoglobin content in red blood cells is reduced (hypochromia), if more than 1, it is increased (hyperchromia).

Myoglobin. Skeletal and cardiac muscles contain muscle hemoglobin (myoglobin). It has similarities and differences with blood hemoglobin. The similarity of these two substances is expressed by the presence of the same prosthetic group, the same amount of iron, and the ability to form reversible compounds with O and CO. However, the mass of myoglobin is much smaller, and it has a much greater affinity for oxygen than blood hemoglobin, and is therefore adapted to the function of storing (binding) oxygen, which is of great importance for supplying oxygen to contracting muscles. When muscles contract, their blood supply is temporarily reduced due to constriction of the capillaries. And at this moment, myoglobin serves as an important source of oxygen. It “stores” oxygen during relaxation and releases it during contraction. Myoglobin content increases under the influence of muscle loads.

Erythrocyte sedimentation rate (ESR). To determine ESR, blood is mixed with a solution of sodium citrate, and a test tube with millimeter graduations is collected in a glass tube. After some time, the height of the upper transparent layer is counted. ESR varies among animals of different species. Horse erythrocytes settle very quickly, and ruminants settle very slowly. The value of ESR is influenced by the physiological state of the body. Strenuous training slows down this reaction. In sports horses selected for Olympic competition, with an average load, the ESR in the first 15 minutes was 9.6 mm. After 2 months of intense training, in the same first 15 minutes it was 2.6 mm.

ESR increases greatly during pregnancy, as well as during chronic inflammatory processes, infectious diseases, and malignant tumors. This is associated with an increase in the amount of large molecular proteins in the plasma - globulins and especially fibrinogen. Large molecular proteins probably reduce electric charge and electrical repulsion of red blood cells, which contributes to a greater rate of sedimentation.

Lifespan of red blood cells. It is different for different animals. Erythrocytes in a horse remain in the vascular bed for an average of 100 days, in cattle - 120-16, in a sheep - 130, in a reindeer - in a rabbit - 45-60 days.

In 1951, A.L. Chizhevsky, as a result of experimental studies and mathematical calculations, came to the conclusion that in the arterial vessels of healthy people and animals, red blood cells move in a system consisting of coin columns.

Moreover, coin columns of large diameter erythrocytes are adjacent to the slow parietal layer of blood, and coin columns of small diameter erythrocytes are carried in the fast axial blood flow. In addition to translational movement, red blood cells also perform rotational movements around their own axis. In diseases, the spatial arrangement of red blood cells in the vessels is disrupted.

Leukocytes. White blood cells have a cytoplasm and a nucleus. They are divided into two large groups: granular (granulocytes) and non-granular (agranulocytes). The cytoplasm of granular leukocytes contains grains (granules), while the cytoplasm of non-granular leukocytes contains no granules.

Granular leukocytes, depending on the color of the granules, are distinguished as eosinophilic (granules are painted pink with acidic dyes, such as eosin), basophilic (blue with basic dyes) and neutrophilic with both pink-violet dyes). In young granulocytes, the nucleus is round, in young it is in the form of a horseshoe or stick (rod); As it develops, the core is laced and divided into several segments. Segmented neutrophils make up the bulk of granulocytes.

In birds, instead of segmented neutrophils, there are pseudoeosinophils, the cytoplasm of which contains rod-shaped and spindle-shaped granules.

Non-granular leukocytes are divided into lymphocytes and monocytes. Lymphocytes have a large nucleus surrounded by a narrow belt of cytoplasm. Depending on the size, large, medium and small lymphocytes are distinguished. Lymphocytes make up the majority of white blood cells: in cattle

50-60% of all leukocytes, In pigs - 45-60, in sheep - 55-65, in goats - 40-50, in rabbits - 50-65, in chickens - 45-65%. These types of animals are characterized by the so-called lymphocytic blood profile. In horses and carnivores, segmented neutrophils predominate - the neutrophil profile of the blood. However, even in these animals the number of lymphocytes is significant - 20-40% of all leukocytes. Monocytes are the largest blood cells, mostly round in shape, with a well-defined cytoplasm.

In addition, the blood of birds contains Turkic cells - large, with an eccentrically located nucleus and a significant amount of cytoplasm.

The total number of leukocytes in the blood is significantly less than that of red blood cells. In mammals it is about 0.1--0.2% of the number of red blood cells, in birds it is slightly more (about 0.5--1%).

An increase in the number of leukocytes is called leukocytosis, and a decrease is called leukopenia.

There are two types of leukocytosis: physiological and reactive. Physiological, in turn, is divided into:

digestive (a significant increase in the number of leukocytes occurs after eating food; especially pronounced in horses, pigs, dogs and rabbits);

myogenic (develops after heavy muscular work);

emotional;

with painful effects;

during pregnancy.

Physiological leukocytoses are redistributive in nature, that is, leukocytes in these cases leave the depot (spleen, bone marrow, lymph nodes). They are characterized by rapid development, short duration, lack of changes leukocyte formula.

Reactive, or true, leukocytosis occurs in inflammatory processes and infectious diseases. At the same time, the formation of white blood cells in the hematopoietic organs sharply increases and the number of leukocytes in the blood increases more significantly than with redistributive leukocytosis. But the main difference is that with reactive leukocytosis, the leukocyte formula changes: the number of young forms of neutrophils in the blood - myelocytes, young, and stab - increases. The severity of the disease and the reactivity of the body are assessed by the nuclear shift to the left.

Recently, leukopenias are more common than before. This is due to an increase in background radioactivity and other reasons related to technological progress. Particularly severe leukopenia caused by bone marrow damage is observed with radiation sickness. Leukopenia is also detected in some infectious diseases (calf paratyphoid fever, swine fever).

Functions of leukocytes. Leukocytes play an important role in the protective and regenerative processes of the body. Monocytes and neutrophils are capable of amoeboid movement. The speed of movement of the latter can reach up to 40 μm/m, which is equal to a distance 3-4 times greater than the diameter of these cells. These types of leukocytes pass through the endothelium of the capillaries and move in the tissues to the place of accumulation of microbes, foreign particles or decaying cells of the body itself. One neutrophil can capture up to 20-30 bacteria, and a monocyte phagocytoses up to 100 microbes. In addition to proteolytic enzymes, these forms of leukocytes secrete, also adsorb on their surface and transport substances that neutralize microbes and foreign proteins- antibodies.

Basophils have a weak ability for phagocytosis or do not show it at all. Like mast cells of connective tissue, they synthesize heparin, a substance that prevents blood clotting. In addition, basophils are capable of producing histamine. Heparin prevents blood clotting, and histamine expands the capillaries at the site of inflammation, which accelerates the process of resorption and healing.

Lymphocytes take part in the production of antibodies, therefore they are of great importance in creating immunity to infectious diseases (infectious immunity), and are also responsible for reactions to the introduction of foreign proteins and rejection of foreign tissue during organ transplantation (transplantation immunity).

The leading role in immunity, especially transplantation, is played by the so-called T-lymphocytes. They are formed from precursor cells in the bone marrow, undergo differentiation in the thymus (thymus gland), and then move to the lymph nodes, spleen or circulating blood, where they account for 40-70% of all lymphocytes. T lymphocytes are heterogeneous. Among them there are several groups:

1) helpers (assistants) interact with B lymphocytes and transform them into plasma cells that synthesize antibodies;

2) suppressors - suppress excessive reactions of B-lymphocytes and maintain a constant ratio of different forms of lymphocytes;

H) killers (killers) - interact with foreign cells and destroy them;

4) amplifiers - activate killers;

5) immune memory cells

B lymphocytes are formed in the bone marrow, differentiated in mammals in the lymphoid tissue of the intestine, appendix, pharyngeal and palatine tonsils. In birds, differentiation takes place in the bursa of Fabricius. The Latin word for bursa is bursa, hence B lymphocytes. They account for 20-30% of circulating lymphocytes. The main function of B lymphocytes is to produce antibodies and create humoral immunity. After meeting the antigen, B lymphocytes move to the bone marrow, spleen, and lymph nodes, where they multiply and turn into plasma cells that form antibodies and immune globulins. B lymphocytes are specific: each group of them reacts with only one antigen and is responsible for the production of antibodies only against it.

There are also so-called zero lymphocytes, which do not undergo differentiation in the organs of the immune system, but, if necessary, can turn into T and B lymphocytes. They make up 10-20% of lymphocytes.

Lifespan of leukocytes. Most of them live relatively short lives. Using the technique of labeled atoms, it was established that granulocytes live a maximum of 8-10 days, often much less - hours and even minutes. The average lifespan of neutrophils in a calf is 5 hours. Among lymphocytes, short-lived and long-lived forms are distinguished. The first (B-lymphocytes) live from several hours to a week, the second (T-lymphocytes) can live for months and even years.

Blood platelets (platelets). In mammals, these blood cells do not have nuclei; in birds and all lower vertebrates there are nuclei. Blood plates have the amazing property of changing shape and size depending on location. Thus, in the blood stream they have the shape of a ball with a diameter of half a micron (at the resolution limit of an optical microscope). But once on the wall of a blood vessel or on a glass slide, they spread out, from round to star-shaped, increasing their area by 5-10 times, their diameter becomes from 2 to 5 microns. The number of blood platelets depends on the type of animal. It increases with heavy muscular work, digestion, and during pregnancy. Daily fluctuations were also noted: there are more of them during the day than at night. The number of blood platelets decreases in acute infectious diseases and anaphylactic shock.

In 1882, the Russian scientist V.P. Obraztsov first proved that platelets are independent elements of the blood, originating from red bone marrow cells - megakaryocytes (diameter up to 140 microns). Megakaryocyte- a cell with a huge nucleus. For a long time, the “explosion theory” was accepted, according to which a “mature” megakaryocyte seems to explode, disintegrating into small particles - platelets. Moreover, the megakaryocyte nucleus also disintegrates, transferring a certain supply of the substance of heredity - DNA - to platelets. However, careful studies under an electron microscope did not confirm this hypothesis. It turned out that in the cytoplasm of a megakaryocyte, under the control of its giant nucleus, the conception and development of 3-4 thousand platelets occurs. The megakaryocyte then releases its cytoplasmic processes through the walls of the blood vessels. The processes contain mature blood platelets, they tear off, enter the bloodstream and begin to perform their functions. But the megakaryocyte does not cease to exist. Its nucleus grows new cytoplasm, in which a new cycle of birth, maturation and “birth” of plates takes place. Thus, the “explosion theory” was replaced by the “birth theory”. Each megakaryocyte produces 8-10 generations of platelets during its existence in the bone marrow. The plates are released into the blood from the bone marrow in a mature state with a full set of organelles, but without a nucleus and nuclear hereditary material (DNA). They exist, but do not develop, spend themselves, but do not recover. In the absence of a nucleus in the blood stream, only synthesis is possible due to the reserves of substances and energy received from the megakaryocyte. That is why each platelet does not live long in the bloodstream (3-5 days).

In a light microscope, the plates look like pieces of cytoplasm with a small number of grains inside. Using an electron microscope, it was shown that behind the apparent simplicity there is hidden a unique and complex organization. The chemical composition of blood platelets also turned out to be very complex. They contain the enzymes adrenaline, norepinephrine, lysozyme, ATP, serotonin granules and a number of other substances.

Functions of platelets. Platelets perform various functions. First of all, they are involved in the process of blood clotting.

Having a very sticky surface, they are able to quickly stick to the surface of a foreign object. When they come into contact with foreign bodies or a rough surface, platelets stick together, and then break up into small fragments, and at the same time substances lying in the mitochondria are released - the so-called lamellar, or platelet factors, which are usually denoted by Arabic numerals. They take part in all phases of blood coagulation.

Platelets serve as building materials for the primary thrombus. When blood clots, the blood platelets release tiny processes - star-shaped tendrils, then interlock with them, forming a frame on which a blood clot is formed - a thrombus.

Platelets also secrete substances necessary for the compaction of a blood clot - retractozymes. The most important of them is thrombostenin, which in its properties resembles skeletal muscle actomyosin.

Platelet-derived growth factor (TGF) is released from blood platelets into wounded tissue, which stimulates cell division, so the wound heals quickly.

Platelets strengthen the walls of blood vessels. The inner wall of the vessel is formed by epithelial cells, but its strength is determined by the adhesion of parietal platelets. And they are always located along the walls of blood vessels, serving as a kind of barrier. When the strength of the vessel wall is increased, the vast majority of wall platelets have a dendritic, most “tenacious” form, and many of them are at different stages of penetration into epithelial cells. Without interaction with platelets, the vascular endothelium begins to allow red blood cells to pass through.

Platelets transport various substances. For example, serotonin, which is adsorbed by platelets from the blood. This substance constricts blood vessels and reduces bleeding. Platelets also carry the so-called creative substances necessary to preserve the structure of the vascular wall. About 15% of platelets circulating in the blood are used for these purposes.

Platelets have the ability to phagocytose. They absorb and digest foreign particles, including viruses.

BLOOD CLOTTING

When a blood vessel is injured, the blood clots and a blood clot forms, which clogs the defect and prevents further bleeding. Blood clotting, or hemocoagulation, protects the body from blood loss and is the body’s most important protective reaction. With reduced blood clotting, even a minor injury can lead to death.

The rate of blood clotting varies among animals of different species. Blood clotting can occur inside blood vessels when their inner lining (intima) is damaged or due to increased blood clotting. In these cases, vascular blood clots form inside, which pose a danger to the body.

Blood coagulation is caused by a change in the physicochemical state of the plasma protein fibrinogen, which at the same time changes from a soluble to an insoluble form, turning into fibrin. Thin and long fibrin filaments form a network, in the loops of which there are formed elements. If you continuously stir the blood released from the vessel with a whisk, fibrin fibers will settle on it. Blood from which fibrin has been removed is called defibrinated. It consists of formed elements and serum. Blood serum- this is plasma in which there is no fibrinogen and some other substances involved in coagulation.

Not only whole blood, but also plasma can clot.

Modern theory of blood coagulation. It is based on the enzymatic theory of A. Schmidt (1872). According to the latest data, blood coagulation occurs in three phases: 1 - formation of prothrombinase, 2 - formation of thrombin, 3 - formation of fibrin.

In addition, the prephase and postphase of blood coagulation are distinguished. In the prephase, the so-called vascular-platelet, or microcirculatory, hemostasis is carried out. The post-phase includes two parallel processes: retraction (compaction) And fibrinolysis (dissolution) blood clot.

Hemostasis is a set of physiological processes that culminate in stopping bleeding when blood vessels are damaged. Vascular-platelet, or microcirculatory, hemostasis - stopping bleeding from small vessels with low blood pressure. It consists of two sequential processes: vasospasm and the formation of a platelet plug.

In case of injury, a reflex decrease in the lumen (spasm) of small blood vessels occurs. The reflex spasm is short-term. Longer vascular spasm is maintained by vasoconstrictor substances (serotonin, norepinephrine, adrenaline), which are secreted by platelets and damaged tissue cells. Vasospasm leads only to a temporary stop of bleeding.

The formation of a platelet plug is of primary importance for stopping bleeding in small vessels. A platelet plug is formed due to the ability of platelets to stick to a foreign surface (platelet adhesion) and stick together (platelet aggregation). The resulting platelet clot is then compacted as a result of the contraction of a special protein, thrombostenin, contained in platelets.

Stopping bleeding when small vessels are injured occurs in animals within 4 minutes. This hemostasis in vessels with low pressure is called primary. It is caused by prolonged spasm of blood vessels and mechanical blockage of platelet aggregates.

Secondary hemostasis ensures tight closure of damaged vessels by a thrombus. It protects against resumption of bleeding from small vessels and serves as the main mechanism of protection against bleeding when muscle-type vessels are damaged. In this case, irreversible platelet aggregation and clot formation occur.

In large vessels, hemostasis also begins with the formation of a platelet plug, but it cannot withstand high pressure and is washed out. In these vessels, coagulation (enzymatic) hemostasis takes place, carried out in three phases.

First phase. The formation of prothrombinase is the most complex and lengthy. There are tissue and blood and tissue prothrombinases.

The formation of tissue prothrombinase occurs in 5-10 s, and blood prothrombinase in 5-10 minutes.

The process of formation of tissue prothrombinase begins with damage to the walls of blood vessels and surrounding tissues and the release of tissue thrombin, which is fragments of cell membranes (phospholipids), into the blood. Substances contained in plasma, the so-called plasma factors, also take part in this process: VII - convertin, V - globulin - accelerator, X - thrombotropin and IV - calcium cations. The formation of tissue prothrombinase serves as a trigger for subsequent reactions.

The process of formation of blood prothrombinase begins with the activation of a special plasma substance - factor XII, or Hageman factor. In the circulating blood it is in an inactive state, which is due to the presence of an antifactor in the plasma that prevents its activation. Upon contact with a rough surface, the antifactor is destroyed, and then the Hageman factor is activated. The rough surface is the collagen fibers exposed when a blood vessel is damaged. With the activation of the Hageman factor, a chain reaction begins. Factor XII activates factor XI, a precursor of plasma thromboplastin, and forms a complex with it called contact factor. Under the influence of the contact factor, factor IX - antihemophilic globulin B is activated, which reacts with factor VIII antihemophilic globulin A - and calcium ions, forming a calcium complex.

The latter has a strong effect on blood platelets. They stick together, swell and secrete granules containing platelet factor Z. Contact factor, calcium complex and platelet factor form an intermediate product that activates factor X. The latter factor forms a complex on fragments of cell membranes, platelets and erythrocytes (blood thromboplastin) by combining with the factor V and calcium ions. This completes the formation of blood prothrombinase. The main link here is the active factor X.

Blood consists of formed elements (42-46%) erythrocytes (red blood cells), leukocytes (white blood cells) and platelets (blood platelets) and a liquid part plasma (54-58%). Blood plasma devoid of fibrinogen is called serum. In an adult, the total amount of blood is 5-8% of body weight, which corresponds to 5-6 liters. Blood volume is usually denoted in relation to body weight (ml? kg-1). On average, it is 65 ml * kg1 for men, 60 ml * kg-1 for women, and about 70 ml * kg1 for children.

The number of red blood cells in the blood is about a thousand times higher than leukocytes, and tens of times higher than platelets. The latter are several times smaller in size than red blood cells. Therefore, red blood cells make up more than 90% of the total volume of blood cells. The ratio of the volume of formed elements to the total volume of blood, expressed as a percentage, is called hematocrit. In men, the hematocrit averages 46%, in women 42%. This means that in men, formed elements occupy 46%, and plasma 54% of the blood volume, and in women 42 and 58%, respectively. This difference is due to the fact that men have more red blood cells in their blood than women. Children have a higher hematocrit than adults; During aging, hematocrit decreases. An increase in hematocrit is accompanied by an increase in blood viscosity (its internal friction), which in a healthy adult is 4-5 units. Since peripheral resistance to blood flow is directly proportional to viscosity, any significant increase in hematocrit increases the load on the heart, as a result of which blood circulation in some organs may be impaired.

Blood performs a number of physiological functions in the body.

Transport function blood is the transfer of all substances necessary for the functioning of the body (nutrients, gases, hormones, enzymes, metabolites).

The respiratory function consists of delivering oxygen from the lungs to the tissues and carbon dioxide from the tissues to the lungs. Oxygen is transported predominantly by red blood cells in the form of a compound with hemoglobin oxyhemoglobin (HbO2), carbon dioxide by blood plasma in the form of bicarbonate ions (HCO3-). Under normal conditions, when breathing air, 1 g of hemoglobin adds 1.34 ml of oxygen, and since one liter of blood contains 140-160 g of hemoglobin, the amount of oxygen in it is about 200 ml; this value is usually called the oxygen capacity of the blood (sometimes this indicator is calculated per 100 ml of blood).

Thus, if we take into account that the total volume of blood in the human body is 5 liters, then the amount of oxygen associated with hemoglobin in it will be equal to about one liter.

The nutritional function of blood is due to the transfer of amino acids, glucose, fats, vitamins, enzymes and minerals from the digestive organs to tissues, systems and depots.

The thermoregulatory function is ensured by the participation of blood in the transfer of heat from the organs and tissues in which it is produced to the organs that give off heat, which maintains temperature homeostasis.

The excretory function is aimed at transporting metabolic products (urea, creatine, indican, uric acid, water, salts, etc.) from the places of their formation to the excretory organs (kidneys, lungs, sweat and salivary glands).

The protective function of blood, first of all, is the formation of immunity, which can be either innate or acquired. There are also tissue and cellular immunity. The first of them is caused by the production of antibodies in response to the entry of microbes, viruses, toxins, poisons, and foreign proteins into the body; the second is associated with phagocytosis, in which the leading role belongs to leukocytes, which actively destroy microbes and foreign bodies entering the body, as well as their own dying and mutagenic cells.

The regulatory function consists of both humoral (transfer of hormones, gases, and minerals by blood) and reflex regulation associated with the influence of blood on vascular interoreceptors.

Formed elements of blood

The formation of blood cells is called hematopoiesis. It is carried out in various hematopoietic organs. The bone marrow produces red blood cells, neutrophils, eosinophils and basophils. In the spleen and lymph nodes leukocytes are formed. Monocytes are formed in the bone marrow and in the reticular cells of the liver, spleen and lymph nodes. Platelets are produced in the red bone marrow and spleen.

Functions of red blood cells

Basic physiological function red blood cells are the binding and transport of oxygen from the lungs to organs and tissues. This process is carried out due to the structural features of red blood cells and the chemical composition of hemoglobin.

Red blood cells are highly specialized anucleate blood cells with a diameter of 7-8 microns. Human blood contains 4.5-5-1012 * l-1 red blood cells. The shape of red blood cells in the form of a biconcave disc provides large surface for the free diffusion of gases through its membrane. The total surface area of ​​all red blood cells in the circulating blood is about 3000 m2.

In the initial phases of their development, red blood cells have a nucleus and are called reticulocytes. Under normal conditions, reticulocytes make up about 1% of total number red blood cells circulating in the blood. An increase in the number of reticulocytes in peripheral blood may depend both on the activation of erythrocytosis and on the increased release of reticulocytes from the bone marrow into the bloodstream. The average lifespan of mature red blood cells is about 120 days, after which they are destroyed in the liver and spleen.

During the movement of blood, red blood cells do not settle, since they repel each other, since they have the same negative charges. When blood settles in a capillary, red blood cells settle to the bottom. The erythrocyte sedimentation rate (ESR) under normal conditions in men is 4-8 mm per 1 hour, in women 6-10 mm per 1 hour.

As erythrocytes mature, their nucleus is replaced by the respiratory pigment - hemoglobin (Hb), which makes up about 90% of the dry matter of erythrocytes, and 10% is mineral salts, glucose, proteins and fats. Hemoglobin is a complex chemical compound whose molecule consists of the globin protein and the iron-containing part heme. Hemoglobin has the ability to easily combine with acid/fool and just as easily give it away. Combining with oxygen, it becomes oxyhemoglobin (HbO2, and by giving it away it turns into reduced (reduced) hemoglobin. Hemoglobin in human blood makes up 14-15% of its mass, i.e. about 700 g.

Skeletal and cardiac muscles contain a protein similar in structure to myoglobin (muscle hemoglobin). It combines with oxygen more actively than hemoglobin, providing it to working muscles. The total amount of myoglobin in humans is about 25% of blood hemoglobin. Myoglobin is found in greater concentrations in muscles that perform functional loads. Under the influence of physical activity, the amount of myoglobin in the muscles increases.

Functions of leukocytes

Leukocytes by functional and morphological characteristics They are ordinary cells containing a nucleus and protoplasm. The number of leukocytes in the blood of a healthy person is 4 6 * 109 * l-1. Leukocytes are heterogeneous in their structure: in some of them the protoplasm has a granular structure (granulocytes), and in others there is no granularity (agranulocytes). Granulocytes make up 65-70% of all leukocytes and are divided depending on the ability to stain with neutral, acidic or basic dyes into neutrophils, eosinophils and basophils.

Agranulocytes make up 30-35% of all white blood cells and include lymphocytes and monocytes. The functions of different leukocytes are varied.

The percentage of different forms of leukocytes in the blood is called the leukocyte formula. The total number of leukocytes and the leukocyte formula are not constant. An increase in the number of leukocytes in peripheral blood is called leukocytosis, and a decrease is called leukopenia. The lifespan of leukocytes is 7-10 days.

Neutrophils make up 60-70% of all white blood cells and are the most important cells in the body's defense against bacteria and their toxins. Penetrating through the walls of capillaries, neutrophils enter the interstitial spaces, where phagocytosis occurs - the absorption and digestion of bacteria and other foreign protein bodies.

Eosinophils (1-4% of the total number of leukocytes) adsorb antigens (foreign proteins), many tissue substances and protein toxins onto their surface, destroying and neutralizing them. In addition to the detoxification function, eosinophils take part in preventing the development of allergic reactions.

Basophils make up no more than 0.5% of all leukocytes and carry out the synthesis of heparin, which is part of the anticoagulation system of the blood. Basophils are also involved in the synthesis of a number of biologically active substances and enzymes (histamine, serotonin, RNA, phosphatase, lipase, peroxidase).

Lymphocytes (25-30% of all leukocytes) play a vital role in the formation of the body's immunity, and are also actively involved in neutralizing various toxic substances.

The main factors of the immunological system of the blood are T- and B-lymphocytes. T lymphocytes primarily play the role of a strict immune controller. Having come into contact with any antigen, they remember its genetic structure for a long time and determine the program for the biosynthesis of antibodies (immunoglobulins), which is carried out by B lymphocytes. B-lymphocytes, having received a program for the biosynthesis of immunoglobulins, turn into plasma cells, which are an antibody factory.

T-lymphocytes synthesize substances that activate phagocytosis and protective inflammatory reactions. They monitor the genetic purity of the body, preventing the engraftment of foreign tissues, activating regeneration and destroying dead or mutant (including tumor) cells of their own body. T-lymphocytes also play an important role as regulators of hematopoietic function, which consists in the destruction of foreign stem cells in the south of the brain. L lymphocytes are capable of synthesizing beta and gamma globulins, which are part of antibodies.

Unfortunately, lymphocytes cannot always fulfill their role in the formation of an effective immune system. In particular, the human immunodeficiency virus (HIV), which causes the terrible disease AIDS (acquired immunodeficiency syndrome), can sharply reduce the body's immunological defense. The main trigger for AIDS is the penetration of HIV from the blood into T-lymphocytes. There, the virus can remain in an inactive, latent state for several years, until immunological stimulation of T-lymphonitis begins in connection with a secondary infection. Then the virus is activated and multiplies so rapidly that the viral cells, leaving the affected lymphocytes, completely damage the membrane and destroy them. The progressive death of lymphocytes reduces the body's resistance to various intoxications, including microbes that are harmless to a person with normal immunity. In addition, the destruction of mutant (cancer) cells by T lymphocytes is sharply weakened, and therefore the likelihood of malignant tumors significantly increases. The most common manifestations of AIDS are. pneumonia, tumors, central nervous system lesions and pustular diseases of the skin and mucous membranes.

Primary and secondary disorders in AIDS cause a variegated picture of changes in peripheral blood. Along with a significant decrease in the number of lymphocytes, neutrophilic leukocytosis may occur in response to inflammation or pustular lesions of the skin (mucous membranes). When the blood system is damaged, foci of pathological hematopoiesis appear and immature forms of leukocytes will enter the blood in large quantities. With internal bleeding and exhaustion of the patient, progressive anemia begins to develop with a decrease in the number of red blood cells and hemoglobin in the blood.

Monocytes (4-8%) are the largest white blood cells, called macrophages. They have the highest phagocytic activity in relation to the breakdown products of cells and tissues, and also neutralize toxins formed in areas of inflammation. It is also believed that monocytes take part in the production of antibodies. Macrophages, along with monocytes, include reticular and endothelial cells of the liver, spleen, bone marrow and lymph nodes.

Platelet functions

Platelets are small, anucleate blood platelets (Bizzoceri plaques) of irregular shape, 2-5 microns in diameter. Despite the absence of a nucleus, platelets have an active metabolism and are the third independent living blood cell. Their number in peripheral blood ranges from 250 to 400 * 10 9 * l -1; The lifespan of platelets is 8-12 days.

Platelets play a leading role in blood clotting. Lack of platelets in the blood thrombopenia is observed in some diseases and is expressed in increased bleeding.

Physicochemical properties of blood plasma

Blood and human plasma is a colorless liquid containing 90-92% water and 8-10% solids, which include glucose, proteins, fats, various salts, hormones, vitamins, metabolic products, etc. Physicochemical properties of plasma determined by the presence of organic and mineral substances in it, they are relatively constant and are characterized by a number of stable constants.

The specific gravity of plasma is 1.02-1.03, and the specific gravity of blood is 1.05-1.06; in men it is slightly higher (more red blood cells) than in women.

Osmotic pressure is the most important property of plasma. It is inherent in solutions separated from each other by semi-permeable membranes, and is created by the movement of solvent (water) molecules through the membrane towards a higher concentration of soluble substances. The force that drives and moves the solvent, ensuring its penetration through a semipermeable membrane, is called osmotic pressure. Mineral salts play the main role in the osmotic pressure. In humans, the osmotic pressure of the blood is about 770 kPa (7.5-8 atm). That part of the osmotic pressure that is due to plasma proteins is called oncotic. Of the total osmotic pressure, proteins account for approximately 1/200, which is approximately 3.8 kPa.

Blood cells have the same osmotic pressure as plasma. A solution having an osmotic pressure equal to blood pressure is optimal for formed elements and is called isotonic. Solutions of lower concentration are called hypotonic; water from these solutions enters the red blood cells, which swell and can rupture; they undergo hemolysis. If a lot of water is lost from the blood plasma and the concentration of salts in it increases, then, due to the laws of osmosis, water from the red blood cells begins to enter the plasma through their semi-permeable membrane, which causes wrinkling of the red blood cells; Such solutions are called hypertonic. The relative constancy of osmotic pressure is ensured by osmoreceptors and is realized mainly through the excretory organs.

The acid-silk state is one of the important constants of liquid internal environment the body and is an active reaction determined by the quantitative ratio of H+ and OH- ions. IN clean water contains equal amounts of H+ and OH- ions, so it is neutral. If the number of H+ ions per unit volume of solution exceeds the number of OH- ions, the solution has an acidic reaction; if the ratio of these ions is the opposite, the solution is alkaline. To characterize the active reaction of the blood, the hydrogen index, or pH, is used, which is the negative decimal logarithm of the concentration of hydrogen ions. In chemically pure water at a temperature of 25°C, the pH is 7 (neutral reaction). An acidic environment (acidosis) has a pH below 7, an alkaline environment (alkalosis) has a pH above 7. The blood has a slightly alkaline reaction: pH arterial blood equal to 7.4; pH venous blood 7.35, which is due high content it contains carbon dioxide.

Blood buffer systems ensure the maintenance of relative constancy of the active blood reaction, i.e., they regulate the acid-base state. This ability of the blood is due to the special physicochemical composition of buffer systems that neutralize acidic and alkaline products that accumulate in the body. Buffer systems consist of a mixture of weak acids with their salts formed by strong bases. There are 4 buffer systems in the blood: 1) bicarbonate buffer system carbonic acid-sodium bicarbonate (H2CO3 NaHCO3), 2) phosphate buffer system monobasic-dibasic sodium phosphate (NaH2PO4-Na2HPO4); 3) hemoglobin buffer system reduced hemoglobin-potassium salt of hemoglobin (HHv-KHvO2); 4) plasma protein buffer system. In maintaining the buffering properties of blood, the leading role belongs to hemoglobin and its salts (about 75%), to a lesser extent to bicarbonate, phosphate buffers and plasma proteins. Plasma proteins play the role of a buffer system due to their amphoteric properties. In an acidic environment they behave like alkalis, binding acids. IN alkaline environment proteins react as acids that bind alkalis.

All buffer systems create an alkaline reserve in the blood, which is relatively constant in the body. Its value is measured by the number of milliliters of carbon dioxide that can be bound by 100 ml of blood at a CO2 tension in plasma equal to 40 mm Hg. Art. Normally it is equal to 50-65 volume percent CO2. Reserve alkalinity of the blood acts primarily as a reserve of buffer systems against a shift in pH to the acidic side.

The colloidal properties of blood are provided mainly by proteins and, to a lesser extent, by carbohydrates and lipoids. The total amount of proteins in blood plasma is 7-8% of its volume. Plasma contains a number of proteins that differ in their properties and functional significance: albumins (about 4.5%), globulins (2-3%) and fibrinogen (0.2-0.4%).

Blood plasma proteins function as regulators of complete exchange between blood and tissues. The viscosity and buffering properties of blood depend on the amount of proteins; they play an important role in maintaining plasma oncotic pressure.

Blood clotting and transfusion

The liquid state of the blood and the closedness of the bloodstream are necessary conditions vital activity of the body. These conditions are created by the blood coagulation system (hemocoagulation system), which keeps circulating blood in a liquid state and prevents its loss through damaged vessels through the formation of blood clots; stopping bleeding is called hemostasis.

At the same time, in case of large blood losses, some poisonings and diseases, there is a need for blood transfusion, which must be carried out with strict adherence to its compatibility.

Blood clotting

The founder of the modern enzymatic theory of blood coagulation is Professor of Dorpat (Tartu) University A. A. Schmidt (1872). Subsequently, this theory was significantly expanded and it is currently believed that blood coagulation goes through three phases: 1) the formation of prothrombinase, 2) the formation of thrombin, 3) the formation of fibrin.

The formation of prothrombinase is carried out under the influence of thromboplastin (thrombokinase), which is phospholipids of degrading platelets, tissue cells and blood vessels. Thromboplastin is formed with the participation of Ca2+ ions and some plasma coagulation factors.

The second phase of blood coagulation is characterized by the conversion of inactive prothrombin of blood platelets under the influence of prothrombinase into active thrombin. Prothrombin is a glucoprotein formed by liver cells with the participation of vitamin K.

In the third phase of coagulation, insoluble fibrin protein is formed from soluble blood fibrinogen, activated by thrombin, the threads of which form the basis of a blood clot (thrombus), stopping further bleeding. Fibrin also serves as a structural material in wound healing. Fibrinogen is the largest molecular protein in plasma and is produced in the liver.

Blood transfusion

The founders of the doctrine of blood groups and the possibility of transfusion from one person to another were K. Landsteiner (1901) and J. Jansky (1903). In our country, blood transfusion was first carried out by the professor of the Military Medical Academy V.N. Shamov in 1919, and in 1928 he was offered a transfusion of cadaveric blood, for which he was awarded the Lenin Prize.

Ya. Jansky identified four blood groups found in people. This classification has not lost its meaning to this day. It is based on a comparison of antigens found in red blood cells (agglutinogens) and antibodies found in plasma (agglutinins). The main agglutinogens A and B and the corresponding agglutinins alpha and beta were isolated. Agglutinogen A and agglutinin alpha, as well as B and beta, are called the same name. Human blood cannot contain substances of the same name. When they meet, an agglutination reaction occurs, i.e. adhesion of red blood cells, and subsequently destruction (hemolysis). In this case, they talk about blood incompatibility.

Red blood cells classified as group I (0) do not contain agglutinogens, while plasma contains alpha and beta agglutinins. Group II (A) erythrocytes contain agglutinogen A, and plasma contains agglutinin beta. Blood group III (B) is characterized by the presence of agglutinogen B in erythrocytes and agglutinin alpha in plasma. IV (AB) blood group is characterized by the content of agglutinogens A and B and the absence of agglutinins.

Transfusion of incompatible blood causes blood transfusion shock a serious pathological condition that can result in the death of a person. Table 1 shows in which cases when blood is transfused from a donor (the person giving blood) to a recipient (the person receiving blood)! agglutination (indicated by a + sign).

Table 1.

People of the first (I) group can be transfused with blood only from this group, and this group can also be transfused into people of all other groups. Therefore, people with group I are called universal donors. People of group IV can be transfused with blood of the same name, as well as blood of all other groups, therefore these people are called universal recipients. The blood of people of groups II and III can be transfused to people with the same name, as well as with group IV. These patterns are reflected in Fig. 1.

Rh compatibility is important during blood transfusion. It was first discovered in the red blood cells of rhesus monkeys. Subsequently, it turned out that the Rh factor is contained in the red blood cells of 85% of people (Rh-positive blood) and is absent in only 15% of people (Rh-negative blood). When repeating blood transfusion to a recipient who is incompatible with the donor's Rh factor, complications arise due to agglutination of incompatible donor red blood cells. This is the result of the action of specific anti-Rhesus agglutinins produced by the reticuloendothelial system after the first transfusion.

When an Rh-positive man marries an Rh-negative woman (which often happens), the fetus often inherits the father's Rh factor. The fetal blood enters the mother's body, causing the formation of anti-Rhesus agglutinins, which lead to hemolysis of the red blood cells of the unborn child. However, for pronounced disorders in the first child, their concentration is insufficient and, as a rule, the fetus is born alive, but with hemolytic jaundice. At repeat pregnancy In the mother's blood, the concentration of anti-Rhesus substances sharply increases, which is manifested not only by hemolysis of the fetus's red blood cells, but also by intravascular coagulation, often leading to its death and miscarriage.

Rice. 1.

Regulation of the blood system

Regulation of the blood system includes maintaining a constant volume of circulating blood, its morphological composition and the physicochemical properties of plasma. There are two main mechanisms for regulating the blood system in the body: nervous and humoral.

The highest subcortical center that carries out nervous regulation of the blood system is the hypothalamus. The cerebral cortex also influences the blood system through the hypothalamus. The efferent influences of the hypothalamus include the mechanisms of hematopoiesis, blood circulation and blood redistribution, its deposition and destruction. Receptors in the bone marrow, liver, spleen, lymph nodes and blood vessels perceive the changes occurring here, and afferent impulses from these receptors serve as a signal for corresponding changes in the subcortical regulatory centers. The hypothalamus, through the sympathetic division of the autonomic nervous system, stimulates hematopoiesis, enhancing erythropoiesis. Parasympathetic nervous influences inhibit erythropoiesis and carry out the redistribution of leukocytes: a decrease in their number in peripheral vessels and an increase in the vessels of internal organs. The hypothalamus also takes part in the regulation of osmotic pressure, maintaining the required level of blood sugar and other physicochemical constants of the blood plasma.

The nervous system has both direct and indirect regulatory effects on the blood system. The direct path of regulation lies in the bilateral connections of the nervous system with the organs of hematopoiesis, blood distribution and blood destruction. Afferent and efferent impulses go in both directions, regulating all processes of the blood system. The indirect connection between the nervous system and the blood system is carried out with the help of humoral intermediaries, which, influencing the receptors of the hematopoietic organs, stimulate or weaken hematopoiesis.

Among the mechanisms of humoral regulation of blood, a special role belongs to biologically active glycoproteins - hematopoietins, synthesized mainly in the kidneys, as well as in the liver and spleen. The production of red blood cells is regulated by erythropoietins, leukocytes by leukopoietins and platelets by thrombopoietins. These substances enhance hematopoiesis in the bone marrow, spleen, liver, and reticuloendothelial system. The concentration of hematopoietins increases with a decrease in the formed elements in the blood, but in small quantities they are constantly contained in the blood plasma of healthy people, being physiological stimulators of hematopoiesis.

Hormones of the pituitary gland (somatotropic and adrenocorticotropic hormones), the adrenal cortex (glucocorticoids), and male sex hormones (androgens) have a stimulating effect on hematopoiesis. Female sex hormones (estrogens) reduce hematopoiesis, so the content of red blood cells, hemoglobin and platelets in the blood of women is less than that of men. There are no differences in the blood picture between boys and girls (before puberty), and they are also absent among older people.

1. Blood is the internal environment of the body. Blood functions. Composition of human blood. Hematocrit Amount of blood, circulating and deposited blood. Indicators of hematocrit and blood quantity in a newborn.

General properties of blood. Formed elements of blood.

Blood and lymph are the internal environment of the body. Blood and lymph directly surround all cells and tissues and provide vital functions. The entire amount of metabolism occurs between cells and blood. Blood is a type of connective tissue that includes blood plasma (55%) and blood cells or formed elements (45%). The formed elements are represented by - erythrocytes (red blood cells 4.5-5 * 10 in 12 l), leukocytes 4-9 * 10 in 9 l, platelets 180-320 * 10 in 9 l. The peculiarity is that the elements themselves are formed outside - in the hematopoietic organs, and why they enter the blood and live for some time. The destruction of blood cells also occurs outside this tissue. The scientist Lang introduced the concept of the blood system, in which he included the blood itself, the hematopoietic and blood-destructive organs and the apparatus for their regulation.

Features - the intercellular substance in this tissue is liquid. The bulk of the blood is in constant movement, due to which humoral connections are made in the body. The amount of blood is 6-8% of body weight, which corresponds to 4-6 liters. A newborn has more blood. Blood mass occupies 14% of body weight and by the end of the first year it decreases to 11%. Half of the blood is in circulation, the main part is located in the depot and represents deposited blood (spleen, liver, subcutaneous vascular systems, pulmonary vascular systems). Preserving blood is very important for the body. The loss of 1/3 can lead to death, and ½ of the blood is a condition incompatible with life. If blood is centrifuged, the blood is separated into plasma and formed elements. And the ratio of red blood cells to total blood volume is called hematocrit( in men 0.4-0.54 l/l, in women - 0.37-0.47 l/l ) .Sometimes expressed as a percentage.

Blood functions -

1. Transport function - transfer of oxygen and carbon dioxide for nutrition. Blood carries antibodies, cofactors, vitamins, hormones, nutrients, water, salts, acids, bases.
2. Protective (body's immune response)
3. Stopping bleeding (hemostasis)
4. Maintaining homeostasis (pH, osmolality, temperature, vascular integrity)
5. Regulatory function (transport of hormones and other substances that change the activity of the organ)

Blood plasma

Organic

Inorganic

Inorganic substances in plasma- Sodium 135-155 mmol/l, chlorine 98-108 mmol/l, calcium 2.25-2.75 mmol/l, potassium 3.6-5 mmol/l, iron 14-32 µmol/l

2. Physico-chemical properties of blood, their features in children.

Physicochemical properties of blood

1. Blood has a red color, which is determined by the content of hemoglobin in the blood.
2. Viscosity - 4-5 units relative to the viscosity of water. In newborns, 10-14 due to the larger number of red blood cells, by the 1st year it decreases to an adult.
3. Density - 1.052-1.063
4. Osmotic pressure 7.6 atm.
5. pH - 7.36(7.35-7.47)

The osmotic pressure of the blood is created by minerals and proteins. Moreover, 60% of the osmotic pressure comes from sodium chloride. Blood plasma proteins create an osmotic pressure of 25-40 mm. mercury column (0.02 atm). But despite its small size, it is very important for retaining water inside the vessels. A decrease in protein content in the cut will be accompanied by edema, because... water begins to enter the cell. It was observed during the Great Patriotic War during the famine. The value of osmotic pressure is determined by cryoscopy. Osmotic pressure temperatures are determined. A decrease in the freezing temperature below 0 - depression of the blood and the freezing temperature of the blood - 0.56 C. - osmotic pressure in this case is 7.6 atm. Osmotic pressure is maintained at a constant level. To maintain osmotic pressure, proper function of the kidneys, sweat glands and intestines is very important. Osmotic pressure of solutions that have the same osmotic pressure. Like blood, they are called isotonic solutions. The most common is 0.9% sodium chloride solution, 5.5% glucose solution. Solutions with lower pressure are hypotonic, and higher ones are hypertonic.

Active blood reaction. Blood buffer system

1. alkalosis

3. Blood plasma. Blood osmotic pressure.

Blood plasma- liquid opalescent liquid of yellowish color, which consists of 91-92% water, and 8-9% is a dense residue. It contains organic and inorganic substances.

Organic- proteins (7-8% or 60-82 g/l), residual nitrogen - as a result of protein metabolism (urea, uric acid, creatinine, creatine, ammonia) - 15-20 mmol/l. This indicator characterizes the functioning of the kidneys. The growth of this indicator indicates renal failure. Glucose - 3.33-6.1 mmol/l - diabetes mellitus is diagnosed.

Inorganic- salts (cations and anions) - 0.9%

Plasma is a yellowish, slightly opalescent liquid, and is a very complex biological medium, which includes proteins, various salts, carbohydrates, lipids, intermediate metabolic products, hormones, vitamins and dissolved gases. It includes both organic and inorganic substances (up to 9%) and water (91-92%). Blood plasma is in close connection with the tissue fluids of the body. A large number of metabolic products enter the blood from tissues, but, thanks to the complex activity of various physiological systems body, the composition of plasma normally does not undergo significant changes.

The amounts of proteins, glucose, all cations and bicarbonate are kept at a constant level and the slightest fluctuations in their composition lead to severe disorders in the normal functioning of the body. At the same time, the content of substances such as lipids, phosphorus, and urea can vary within significant limits without causing noticeable disorders in the body. The concentration of salts and hydrogen ions in the blood is very precisely regulated.

The composition of blood plasma has some fluctuations depending on age, gender, nutrition, geographical features of the place of residence, time and season of the year.

Functional osmotic pressure regulation system. The osmotic pressure of the blood of mammals and humans normally remains at a relatively constant level (Hamburger’s experiment with the introduction of 7 liters of 5% sodium sulfate solution into the blood of a horse). All this occurs due to the activity of the functional system for regulating osmotic pressure, which is closely linked with the functional system for regulating water-salt homeostasis, since it uses the same executive organs.

The walls of blood vessels contain nerve endings that respond to changes in osmotic pressure ( osmoreceptors). Their irritation causes excitation of central regulatory formations in the medulla oblongata and diencephalon. From there, commands come, including certain organs, for example, kidneys, which remove excess water or salts. Among the other executive organs of the FSOD, it is necessary to name the organs of the digestive tract, in which both the removal of excess salts and water and the absorption of products necessary for the restoration of OD occur; skin, the connective tissue of which absorbs excess water when the osmotic pressure decreases or releases it to the latter when the osmotic pressure increases. In the intestine, solutions of mineral substances are absorbed only in such concentrations that contribute to the establishment of normal osmotic pressure and ionic composition of the blood. Therefore, when taking hypertonic solutions(Epsom salt, sea water) dehydration occurs due to the removal of water into the intestinal lumen. The laxative effect of salts is based on this.

A factor that can change the osmotic pressure of tissues, as well as blood, is metabolism, because body cells consume large-molecular nutrients and release significantly larger number molecules of low molecular weight products of their metabolism. This makes it clear why venous blood flowing from the liver, kidneys, and muscles has a higher osmotic pressure than arterial blood. It is no coincidence that these organs contain greatest number osmoreceptors.

Particularly significant shifts in osmotic pressure in the whole organism are caused by muscular work. During very intense work activities excretory organs may not be sufficient to maintain blood osmotic pressure at a constant level and, as a result, it may increase. The shift in blood osmotic pressure to 1.155% NaCl makes it impossible to further perform work (one of the components of fatigue).

4. Blood plasma proteins. Functions of the main protein fractions. The role of oncotic pressure in the distribution of water between plasma and intercellular fluid. Peculiarities protein composition plasma in young children.

Blood plasma proteins are presented in several fractions that can be detected by electrophoresis. Albumin - 35-47 g/l (53-65%), globulins 22.5-32.5 g/l (30-54%), divided into alpha1, alpha 2 (alpha - transport proteins), beta and gamma ( protective bodies) globulins, fibrinogen 2.5 g/l (3%). Fibrinogen is a substrate for blood clotting. A blood clot forms from it. Gamma globulins are produced by plasma cells of lymphoid tissue, the rest in the liver. Plasma proteins take part in the creation of oncotic or colloid-osmotic pressure and are involved in the regulation of water metabolism. Protective function, transport function (transport of hormones, vitamins, fats). Participate in blood clotting. Blood clotting factors are formed by protein components. They have buffering properties. In diseases, the level of protein in the blood plasma decreases.

The most complete separation of blood plasma proteins is carried out using electrophoresis. On the electropherogram, 6 fractions of plasma proteins can be distinguished:

Albumin. They are contained in the blood 4.5-6.7%, i.e. Albumin accounts for 60-65% of all plasma proteins. They perform mainly a nutritional and plastic function. The transport role of albumins is no less important, since they can bind and transport not only metabolites, but drugs. When there is a large accumulation of fat in the blood, some of it is also bound by albumin. Since albumins have very high osmotic activity, they account for up to 80% of the total colloid-osmotic (oncotic) blood pressure. Therefore, a decrease in the amount of albumin leads to disruption of water exchange between tissues and blood and the appearance of edema. Albumin synthesis occurs in the liver. Their molecular weight is 70-100 thousand, so some of them can pass through the renal barrier and be absorbed back into the blood.

Globulins usually accompany albumin everywhere and are the most abundant of all known proteins. The total amount of globulins in plasma is 2.0-3.5%, i.e. 35-40% of all plasma proteins. By faction, their contents are as follows:

alpha1 globulins - 0.22-0.55 g% (4-5%)

alpha2 globulins - 0.41-0.71g% (7-8%)

beta globulins - 0.51-0.90 g% (9-10%)

gamma globulins - 0.81-1.75 g% (14-15%)

The molecular weight of globulins is 150-190 thousand. The place of formation may vary. Most of it is synthesized in lymphoid and plasma cells of the reticuloendothelial system. Part is in the liver. The physiological role of globulins is diverse. Thus, gamma globulins are carriers of immune bodies. Alpha and beta globulins also have antigenic properties, but their specific function is to participate in coagulation processes (these are plasma coagulation factors). This also includes most of the blood enzymes, as well as transferrin, cerulloplasmin, haptoglobins and other proteins.

Fibrinogen. This protein makes up 0.2-0.4 g%, about 4% of all blood plasma proteins. It is directly related to coagulation, during which it precipitates after polymerization. Plasma devoid of fibrinogen (fibrin) is called blood serum.

In various diseases, especially those leading to disturbances in protein metabolism, sharp changes in the content and fractional composition of plasma proteins are observed. Therefore, the analysis of blood plasma proteins has diagnostic and prognostic significance and helps the doctor judge the degree of organ damage.

5. Blood buffer systems, their significance.

Blood buffer system(pH fluctuation by 0.2-0.4 is very serious stress)

1. Bicarbonate (H2CO3 - NaHCO3) 1: 20. Bicarbonates are an alkaline reserve. During the exchange process, many acidic products are formed that need to be neutralized.
2. Hemoglobin (reduced hemoglobin (a weaker acid than oxyhemoglobin. The release of oxygen by hemoglobin leads to the fact that reduced hemoglobin binds a hydrogen proton and prevents the reaction from shifting to the acidic side) - oxyhemoglobin, which binds oxygen)
3. Protein (plasma proteins are amphoteric compounds and, unlike the medium, can bind hydrogen ions and hydroxyl ions)
4. Phosphate (Na2HPO4 (alkaline salt) - NaH2PO4 (acid salt)). Phosphate formation occurs in the kidneys, so the phosphate system works best in the kidneys. The excretion of phosphates in the urine changes depending on the functioning of the kidneys. In the kidneys, ammonia is converted to ammonium NH3 to NH4. Impaired kidney function - acidosis - shift to the acidic side and alkalosis- shift of the reaction to the alkaline side. Accumulation of carbon dioxide due to improper functioning of the lungs. Metabolic and respiratory conditions (acidosis, alkalosis), compensated (without a transition to the acidic side) and uncompensated (alkaline reserves are exhausted, a shift in the reaction to the acidic side) (acidosis, alkalosis)

Any buffer system includes a weak acid and a salt formed by a strong base.

NaHCO3 + HСl = NaCl + H2CO3 (H2O and CO2 are removed through the lungs)

6. Red blood cells, their number, physiological role. Age-related fluctuations in the number of red blood cells.

red blood cells- the most numerous formed elements of blood, the content of which differs in men (4.5-6.5 * 10 in 12 l) and women (3.8-5.8). Nuclear-free highly specialized cells. They have the shape of a biconcave disk with a diameter of 7-8 microns and a thickness of 2.4 microns. This shape increases its surface area, increases the stability of the red blood cell membrane, and can fold when passing through capillaries. Red blood cells contain 60-65% water and 35-40% is dry residue. 95% of the dry residue is hemoglobin - a respiratory pigment. The remaining proteins and lipids account for 5%. Of the total mass of the red blood cell, the mass of hemoglobin is 34%. Red blood cell size (volume) is 76-96 femto/l (-15 degree), the average red blood cell volume can be calculated by dividing the hematocrit by the number of red blood cells per liter. The average hemoglobin content is determined by picograms - 27-32 pico/g - 10 in - 12. Outside, the erythrocyte is surrounded by a plasma membrane (a double lipid layer with integral proteins that penetrate this layer and these proteins are represented by glycophorin A, protein 3, ankyrin. C inside membranes - proteins spectrin and actin. These proteins strengthen the membrane). On the outside, the membrane has carbohydrates - polysaccharides (glycolipids and glycoproteins and polysaccharides carry antigens A, B and III). Transport function of integral proteins. There is sodium-potassium atphase, calcium-magnesium atphase. Inside the red blood cells 20 times more potassium, and sodium is 20 times less than in plasma. The packing density of hemoglobin is high. If the red blood cells in the blood have different sizes, this is called anisocytosis, if the form differs, it is called oikelocytosis. Red blood cells are formed in the red bone marrow and then enter the blood, where they live for an average of 120 days. Metabolism in red blood cells is aimed at maintaining the shape of the red blood cell and maintaining the affinity of hemoglobin for oxygen. 95% of glucose absorbed by red blood cells undergoes anaerobic glycolysis. 5% uses the pentose phosphate pathway. A by-product of glycolysis is the substance 2,3-diphosphoglycerate (2,3 - DPG). Under conditions of oxygen deficiency, more of this product is formed. When DPG accumulates, oxygen release from oxyhemoglobin is easier.

Functions of red blood cells

1. Respiratory (O2, CO2 transport)
2. Transfer of amino acids, proteins, carbohydrates, enzymes, cholesterol, prostaglandins, trace elements, leukotrienes
3. Antigenic function (antibodies can be produced)
4. Regulatory (pH, ionic composition, water exchange, erythropoiesis process)
5. Formation of bile pigments (bilirubin)

An increase in red blood cells (physiological erythrocytosis) in the blood will be promoted by physical activity, food intake, and neuropsychic factors. The number of red blood cells increases in mountain residents (7-8 * 10 in 12). For blood diseases - erythrimymia. Anemia - a decrease in the content of red blood cells (due to lack of iron, failure to absorb folic acid (vitamin B12)).

Counting the number of red blood cells in the blood.

Produced in a special counting chamber. Chamber depth 0.1 mm. There is a gap of 0.1 mm under the cover stele and the chamber. On the middle part there is a grid - 225 squares. 16 small squares (side of a small square 1/10 mm, 1/400 - area, volume - 1/4000 mm3)

We dilute the blood 200 times with a 3% sodium chlorine solution. Red blood cells shrink. This diluted blood is fed under a cover glass into a counting chamber. Under a microscope, we count the number in 5 large squares (90 small ones), divided into small ones.

Number of red blood cells = A (number of red blood cells in five large squares) * 4000 * 200/80

7. Hemolysis of erythrocytes, its types. Osmotic resistance of erythrocytes in adults and children.

Destruction of the erythrocyte membrane with the release of hemoglobin into the blood. The blood becomes transparent. Depending on the causes of hemolysis, it is divided into osmotic hemolysis in hypotonic solutions. Hemolysis can be mechanical. When shaking the ampoules, they can be destroyed, thermal, chemical (alkali, gasoline, chloroform), biological (incompatibility of blood groups).

The resistance of erythrocytes to hypotonic solution changes in different diseases.

Maximum osmotic resistance is 0.48-044% NaCl.

Minimum osmotic resistance - 0.28 - 0.34% NaCl

Erythrocyte sedimentation rate. Red blood cells are kept suspended in the blood due to the small difference in density between red blood cells (1.03) and plasma (1.1). The presence of zeta potential on the red blood cell. Red blood cells are found in plasma, as in a colloidal solution. A zeta potential is formed at the boundary between the compact and diffuse layers. This ensures that red blood cells repel each other. Violation of this potential (due to the introduction of protein molecules into this layer) leads to the gluing of red blood cells (coin columns). The radius of the particle increases, and the segmentation speed increases. Continuous blood flow. The sedimentation rate of 1 erythrocyte is 0.2 mm per hour, and in fact in men (3-8 mm per hour), in women (4-12 mm), in newborns (0.5 - 2 mm per hour). The erythrocyte sedimentation rate obeys Stokes' law. Stokes studied the settling rate of particles. The settling rate of particles (V=2/9R in 2 * (g*(density 1 - density 2)/eta (viscosity in poise))) is observed in inflammatory diseases, when many coarse proteins are formed - gamma globulins. They reduce the zeta potential more and promote subsidence.

8. Erythrocyte sedimentation rate (ESR), mechanism, clinical significance. Age-related changes in ESR.

Blood is a stable suspension of small cells in a liquid (plasma). The property of blood as a stable suspension is disrupted when the blood transitions to a static state, which is accompanied by cell sedimentation and is most clearly manifested by erythrocytes. This phenomenon is used to assess the suspension stability of blood when determining the erythrocyte sedimentation rate (ESR).

If the blood is prevented from clotting, the formed elements can be separated from the plasma by simple settling. This is of practical clinical importance, since ESR changes markedly under certain conditions and diseases. Thus, ESR greatly accelerates in women during pregnancy, in patients with tuberculosis, and in inflammatory diseases. When blood stands, red blood cells stick together (agglutinate), forming so-called coin columns, and then conglomerates of coin columns (aggregation), which settle the faster the larger their size.

The aggregation of erythrocytes, their bonding depends on changes in the physical properties of the surface of erythrocytes (possibly with a change in the sign of the total charge of the cell from negative to positive), as well as on the nature of the interaction of erythrocytes with plasma proteins. The suspension properties of blood depend primarily on the protein composition of the plasma: an increase in the content of coarse proteins during inflammation is accompanied by a decrease in suspension stability and an acceleration of ESR. The value of ESR also depends on the quantitative ratio of plasma and erythrocytes. In newborns, ESR is 1-2 mm/hour, in men 4-8 mm/hour, in women 6-10 mm/hour. ESR is determined using the Panchenkov method (see workshop).

Accelerated ESR, caused by changes in plasma proteins, especially during inflammation, also corresponds to increased aggregation of erythrocytes in the capillaries. The predominant aggregation of erythrocytes in capillaries is associated with a physiological slowdown in blood flow in them. It has been proven that under conditions of slow blood flow, an increase in the content of coarse proteins in the blood leads to more pronounced cell aggregation. Red blood cell aggregation, reflecting the dynamic suspension properties of blood, is one of the oldest protective mechanisms. In invertebrates, erythrocyte aggregation plays a leading role in the processes of hemostasis; during an inflammatory reaction, this leads to the development of stasis (stopping blood flow in the border areas), helping to delineate the source of inflammation.

Recently, it has been proven that what matters in ESR is not so much the charge of erythrocytes, but the nature of its interaction with the hydrophobic complexes of the protein molecule. The theory of neutralization of the charge of erythrocytes by proteins has not been proven.

9. Hemoglobin, its types in the fetus and newborn. Compounds of hemoglobin with various gases. Spectral analysis of hemoglobin compounds.

Oxygen transfer. Hemoglobin attaches oxygen at high partial pressure (in the lungs). There are 4 hemes in the hemoglobin molecule, each of which can attach an oxygen molecule. Oxygenation is the addition of oxygen to hemoglobin, because There is no process of changing the valence of iron. In tissues where the partial pressure is low, hemoglobin releases oxygen - deoxykination. The combination of hemoglobin and oxygen is called oxyhemoglobin. The oxygenation process occurs in stages.

During oxygenation, the process of oxygen addition increases.

Cooperative effect - oxygen molecules at the end join 500 times faster. 1 g of hemoglobin adds 1.34 ml of O2.

100% blood saturation with hemoglobin - maximum percentage (volume) saturation

20ml per 100ml of blood. In fact, hemoglobin is saturated by 96-98%.

The addition of oxygen also depends on pH, on the amount of CO2, 2,3-diphosphoglycerate (a product of incomplete oxidation of glucose). As it accumulates, hemoglobin begins to release oxygen more easily.

Methemoglobin, in which iron becomes trivalent (under the action of strong oxidizing agents - potassium ferricyanide, nitrates, berthollet salt, phenacytin) It cannot give off oxygen. Methemoglobin is capable of binding hydrocyanic acid and other bonds, therefore, in case of poisoning with these substances, methemoglobin is injected into the body.

Carboxyhemoglobin (a compound of Hb with CO) carbon monoxide joins iron in hemoglobin, but the affinity of hemoglobin for carbon monoxide is 300 times higher than for oxygen. If there is more than 0.1% carbon monoxide in the air, then hemoglobin binds with carbon monoxide. 60% is due to carbon monoxide (death). Carbon monoxide is found in exhaust gases, in stoves, and is formed when smoking.

Help for victims - carbon monoxide poisoning begins unnoticed. The person himself cannot move; it is necessary to remove him from this room and provide breathing, preferably with a gas cylinder with 95% oxygen and 5% carbon dioxide. Hemoglobin can combine with carbon dioxide - carbhemoglobin. The connection occurs with the protein part. The acceptor is the amine parts (NH2) - R-NH2+CO2=RNHCOOH.

This compound is capable of removing carbon dioxide. The combination of hemoglobin with different gases has different absorption spectra. Reduced hemoglobin has one broad band in the yellow-green part of the spectrum. Oxyhemoglobin produces 2 bands in the yellow-green part of the spectrum. Methemoglobin has 4 bands - 2 yellow-green, red and blue. Carboxyhemoglobin has 2 bands in the yellow-green part of the spectrum, but this compound can be distinguished from oxyhemoglobin by the addition of a reducing agent. Since carboxyhemoglobin is a strong compound, adding a reducing agent does not add streaks.

Hemoglobin has an important function in maintaining normal pH levels. When releasing oxygen in tissues, hemoglobin attaches a proton. In the lungs, a hydrogen proton is given up to form carbonic acid. When hemoglobin is exposed to strong acids or alkalis, compounds with a crystalline form are formed and these compounds are the basis for confirming blood. Hemins, hemochromogens. Glycine and succinic acid take part in the synthesis of parphyrin (pyrrole ring). Globin is formed from amino acids through protein synthesis. In red blood cells that complete their life cycle, hemoglobin breakdown occurs. In this case, the heme is separated from the protein part. Iron is calved from heme, and bile pigments are formed from heme residues (for example, bilirubin, which will then be captured by liver cells). Inside hepatocytes, hemoglobin combines with glucuronic acid. Bilirubin gyukuronite is excreted into the bile capillaries. It enters the intestine with the bile, where it undergoes oxidation, where it turns into urabillin, which is absorbed into the blood. Some remains in the intestines and is excreted in the feces (their color is stercobillin). Urrabillin colors the urine and is taken up again by the liver cells.

The content of hemoglobin in erythrocytes is judged by the so-called color index, or farb index (Fi, from farb - color, index - indicator) - a relative value characterizing the saturation of an average erythrocyte with hemoglobin. Fi is the percentage ratio of hemoglobin and red blood cells, while 100% (or units) of hemoglobin is conventionally taken to be 166.7 g/l, and 100% of red blood cells is 5*10 /l. If a person has a hemoglobin and red blood cell content of 100%, then the color index is 1. Normally, Fi ranges from 0.75-1.0 and very rarely can reach 1.1. In this case, the red blood cells are called normochromic. If Fi is less than 0.7, then such red blood cells are undersaturated with hemoglobin and are called hypochromic. When Fi is more than 1.1, red blood cells are called hyperchromic. In this case, the volume of the red blood cell increases significantly, which allows it to contain a higher concentration of hemoglobin. As a result, a false impression is created that the red blood cells are oversaturated with hemoglobin. Hypo- and hyperchromia occur only in anemia. Determining the color index is important for clinical practice, as it allows for a differential diagnosis for anemia of various etiologies.

10. Leukocytes, their number and physiological role.

White blood cells. These are nuclear cells without a polysaccharide shell

Dimensions - 9-16 microns

Normal quantity - 4-9 * 10 in 9l

Formation occurs in the red bone marrow, lymph nodes, and spleen.

Leukocytosis - increase in the number of white blood cells

Leukopenia - decrease in the number of leukocytes

Leukocyte count=B*4000*20/400. They count on Goryaev's grid. The blood is diluted with a 5% solution of acetic acid tinted with methylene blue, diluted 20 times. In an acidic environment, hemolysis occurs. Next, the diluted blood is placed in a counting chamber. Count the number in 25 large squares. Counting can be done in undivided and divided squares. The total number of white blood cells counted will correspond to 400 small ones. Let's find out how many leukocytes there are on average per small square. Convert to cubic millimeters (multiply by 4000). We take into account the dilution of blood by 20 times. In newborns, the amount on the first day is increased (10-12*10 in 9 l). By the age of 5-6 years it reaches the level of an adult. An increase in leukocytes is caused by physical activity, food intake, pain, and stressful situations. The amount increases during pregnancy and during cooling. This physiological leukocytosis associated with the release of more leukocytes into circulation. These are redistributive reactions. Daily fluctuations - in the morning there are fewer leukocytes, in the evening - more. In infectious inflammatory diseases, the number of leukocytes increases due to their participation in protective reactions. The number of white blood cells may increase in leukemia (leukemia)

General properties of leukocytes

1. Independent mobility (formation of pseudopodia)
2. Chemotaxis (approach to a focus with a changed chemical composition)
3. Phagocytosis (absorption of foreign substances)
4. Diapedesis - the ability to penetrate the vascular wall

11. Leukocyte formula, its clinical significance. B- and T-lymphocytes, their role.

Leukocyte formula

1. Granulocytes

A. Neutrophils 47-72% (segmented (45-65%), band (1-4%), young (0-1%))

B. Eosinophils (1-5%)

B. Basophils (0-1%)

1. Agranulocytes (no granularity)

A. Lymphocytes (20-40%)

B. Monocytes (3-11%)

Percentage different forms leukocyte - leukocyte formula. Counting on a blood smear. Staining according to Romanovsky. Of 100 leukocytes, how many will be of these varieties. In the leukocyte formula, there is a shift to the left (an increase in young forms of leukocytes) and to the right (the disappearance of young forms and the predominance of segmented forms). A shift to the right characterizes the inhibition of the function of the red bone marrow, when new cells are not formed, but only mature forms are present. No longer favorable. Features of the functions of individual forms. All granulocytes have high cell membrane lability, adhesive properties, chemotaxis, phagocytosis, and free movement.

Neutrophil granulocytes are formed in the red bone marrow and live in the blood for 5-10 hours. Neutrophils contain lysosamal, peroxidase, hydrolytic, Nad-oxidase. These cells are our non-specific protectors from bacteria, viruses, and foreign particles. Their number at infection age. The source of infection is approached using chemotaxis. They are capable of capturing bacteria by phagocytosis. Phagocytosis was discovered by Mechnikov. Absonins, substances that enhance phagocytosis. Immune complexes, C-reactive protein, aggregated proteins, fibronectins. These substances coat foreign agents and make them “tasty” to leukocytes. Upon contact with a foreign object - protrusion. This bubble then separates. Then inside, it fuses with lysosomes. Further, under the influence of enzymes (peroxidase, adoxidase), neutralization occurs. Enzymes break down the foreign agent, but the neutrophils themselves die.

Eosinophils. They phagocytose histamine and destroy it with the enzyme histaminase. Contains a protein that destroys heparin. These cells are necessary to neutralize toxins and capture immune complexes. Eosinophils destroy histamine during allergic reactions.

Basophils - contain heparin (anti-clotting effect) and histamine (dilate blood vessels). Mast cells, which contain receptors for immunoglobulins E on their surface. Active substances are derivatives of arachidonic acid - platelet activation factors, thromboxanes, leukotrienes, prostaglandins. The number of basophils increases in the final stage of the inflammatory reaction (in this case, basophils dilate blood vessels, and heparin facilitates the resorption of the inflammatory focus).

Agranulocytes. Lymphocytes are divided into -

1. 0-lymphocytes(10-20%)
2. T-lymphocytes (40-70%). Development is completed in the thymus. Formed in the red bone marrow
3. B lymphocytes (20%). Place of formation - red bone marrow. The final stage of this group of lymphocytes occurs in the lymphoepithelial cells along the small intestine. In birds, they complete development in a special bursa in the stomach.

12. Age-related changes in the child’s leukocyte formula. The first and second “crossovers” of neutrophils and lymphocytes.

The leukocyte formula, like the number of leukocytes, undergoes significant changes during the first years of a person’s life. If in the first hours a predominance of granulocytes is noted in a newborn, then by the end of the first week after birth the number of granulocytes decreases significantly and their bulk consists of lymphocytes and monocytes. Starting from the second year of life, there is a gradual increase in the relative and absolute number of granulocytes and a decrease in mononuclear cells, mainly lymphocytes. The intersection points of the agranulocyte and granulocyte curves are 5 months and 5 years. In persons aged 14-15 years, the leukocyte formula is practically no different from that of adults.

When assessing leukograms, great importance should be attached not only to the percentage of leukocytes, but also to their absolute values ​​(“leukocyte profile” according to Moshkovsky). It is understandable that a decrease in the absolute number of certain types of leukocytes leads to an apparent increase in the relative number of other forms of leukocytes. Therefore, only the determination of absolute values ​​can indicate changes that are actually taking place.

13. Platelets, their number, physiological role.

Platelets, or blood platelets, are formed from giant cells of the red bone marrow - megakaryocytes. In the bone marrow, megakaryocytes are tightly pressed into the spaces between fibroblasts and endothelial cells, through which their cytoplasm protrudes out and serves as material for the formation of platelets. In the bloodstream, platelets have a round or slightly oval shape, their diameter does not exceed 2-3 microns. The platelet does not have a nucleus, but has a large number of granules (up to 200) of various structures. Upon contact with a surface that differs in its properties from the endothelium, the platelet is activated, spreads out, and up to 10 notches and processes appear, which can be 5-10 times the diameter of the platelet. The presence of these processes is important for stopping bleeding.

Normally, the number of platelets in a healthy person is 2-4-1011 / l, or 200-400 thousand in 1 μl. An increase in the number of platelets is called "thrombocytosis" decrease - "thrombocytopenia". IN natural conditions the number of platelets is subject to significant fluctuations (their number increases with painful stimulation, physical activity, stress), but rarely goes beyond the norm. As a rule, thrombocytopenia is a sign of pathology and is observed when radiation sickness, congenital and acquired diseases of the blood system.

The main purpose of platelets is to participate in the process of hemostasis (see section 6.4). An important role in this reaction belongs to the so-called platelet factors, which are concentrated mainly in the granules and platelet membrane. Some of them are designated by the letter P (from the word platelet - plate) and an Arabic numeral (P 1, P 2, etc.). The most important are P 3, or partial (incomplete) thromboplastin, representing a fragment of cell membrane; P 4, or antiheparin factor; P 5, or platelet fibrinogen; ADF; contractile protein thrombastenin (resembling actomyosin), vasoconstrictor factors - serotonin, adrenaline, norepinephrine, etc. Plays a significant role in hemostasis thromboxane A 2 (TxA 2), which is synthesized from arachidonic acid, which is part of cell membranes (including platelets) under the influence of the enzyme thromboxane synthetase.

On the surface of platelets there are glycoprotein formations that perform the functions of receptors. Some of them are “masked” and are expressed after platelet activation by stimulating agents - ADP, adrenaline, collagen, microfibrils, etc.

Platelets take part in protecting the body from foreign agents. They have phagocytic activity, contain IgG, are a source of lysozyme and β -lysines, which can destroy the membrane of some bacteria. In addition, peptide factors were found in their composition that cause the transformation of “zero” lymphocytes (0-lymphocytes) into T- and B-lymphocytes. These compounds are released into the blood during platelet activation and, in the event of vascular injury, protect the body from pathogenic microorganisms.

Regulators of thrombocytopoiesis are short-term and long acting. They are formed in the bone marrow, spleen, liver, and are also part of megakaryocytes and platelets. Short-acting plateletpoietins enhance the detachment of blood platelets from megakaryocytes and accelerate their entry into the blood; long-acting thrombocytopoietins promote the transition of bone marrow giant cell precursors to mature megakaryocytes. The activity of thrombocytopoietins is directly influenced by IL-6 and IL-11.

14. Regulation of erythropoiesis, leukopoiesis and thrombopoiesis. Hemopoietins.

The continuous loss of blood cells requires their replenishment. They are formed from undifferentiated stem cells in the red bone marrow. From which arise the so-called colony-stimulating (CFU), which are the precursors of all hematopoietic lines. Both bi and unipotent cells can arise from them. From them, differentiation and formation of various forms of erythrocytes and leukocytes occurs.

1. Proerythroblast

2. Erythroblast -

Basophilic

Polychromatic

Orthochromatic (loses the nucleus and becomes a reticulocyte)

3. Reticulocyte (contains remnants of RNA and ribosomes, hemoglobin formation continues) 25-65 * 10 * 9 l turn into mature red blood cells in 1-2 days.

4. Erythrocyte - every minute 2.5 million mature red blood cells are formed.

Factors accelerating erythropoiesis

1. Erythropoietins (formed in the kidneys, 10% in the liver). Accelerate the processes of mitosis, stimulate the transition of reticulocytes to mature forms.

2. Hormones - somatotropic, ACTH, androgenic, hormones of the adrenal cortex, inhibit erythropoiesis - estrogens

3. Vitamins - B6, B12 (external factor of hematopoiesis, but absorption occurs if it combines with the internal factor of Castle, which is formed in the stomach), folic acid.

You also need iron. The formation of leukocytes is stimulated by leukopoietin substances, which accelerate the maturation of granulocytes and promote their release from the red bone marrow. These substances are formed during the breakdown of tissue, in areas of inflammation, which enhances the maturation of leukocytes. There are interleukins, which also stimulate the formation of leukzoites. Growth hormone and adrenal hormones cause leukocytosis (increase in the number of hormones). Thymosin is necessary for the maturation of T lymphocytes. The body has 2 reserves of leukocytes - vascular - accumulation along the walls of blood vessels and bone marrow reserve. In pathological conditions, leukocytes are released from the bone marrow (30-50 times more).

15. Blood coagulation and its biological significance. Rate of coagulation in adults and newborns. Blood clotting factors.

If the blood released from the blood vessel is left for some time, then from the liquid it first turns into jelly, and then a more or less dense clot is organized in the blood, which, by contracting, squeezes out a liquid called blood serum. This is plasma devoid of fibrin. The described process is called blood clotting (by hemocoagulation). Its essence lies in the fact that the fibrinogen protein dissolved in plasma under certain conditions becomes insoluble and precipitates in the form of long fibrin filaments. In the cells of these threads, as in a mesh, cells get stuck and the colloidal state of the blood as a whole changes. The significance of this process is that coagulated blood does not flow out of the wounded vessel, preventing the body from dying from blood loss.

Blood coagulation system. Enzymatic theory of coagulation.

The first theory explaining the process of blood clotting by the work of special enzymes was developed in 1902 by the Russian scientist Schmidt. He believed that coagulation occurs in two phases. First, one of the plasma proteins prothrombin under the influence of enzymes released from blood cells destroyed during injury, especially platelets ( thrombokinase) And Ca ions goes into enzyme thrombin. At the second stage, under the influence of the enzyme thrombin, fibrinogen dissolved in the blood is converted into insoluble fibrin, which causes the blood to clot. In the last years of his life, Schmidt began to distinguish 3 phases in the process of hemocoagulation: 1- formation of thrombokinase, 2- formation of thrombin. 3- formation of fibrin.

Further study of the coagulation mechanisms showed that this representation is very schematic and does not fully reflect the entire process. The main thing is that there is no active thrombokinase in the body, i.e. an enzyme capable of converting prothrombin into thrombin (according to the new nomenclature of enzymes, this should be called prothrombinase). It turned out that the process of prothrombinase formation is very complex; a number of so-called proteins are involved in it. thrombogenic enzyme proteins, or thrombogenic factors, which, interacting in a cascade process, are all necessary for blood clotting to occur normally. In addition, it was discovered that the coagulation process does not end with the formation of fibrin, because its destruction begins at the same time. Thus, the modern blood coagulation scheme is much more complicated than Schmidt’s.

The modern blood coagulation scheme includes 5 phases, successively replacing each other. These phases are as follows:

1. Formation of prothrombinase.

2. Thrombin formation.

3. Fibrin formation.

4. Fibrin polymerization and clot organization.

5. Fibrinolysis.

Over the past 50 years, many substances involved in blood clotting, proteins, the absence of which in the body leads to hemophilia (non-clotting of blood), have been discovered. Having considered all these substances, the international conference of hemocoagulologists decided to designate all plasma coagulation factors in Roman numerals, and cellular coagulation factors in Arabic numerals. This was done in order to eliminate confusion in names. And now in any country, after the generally accepted name of the factor (they can be different), the number of this factor according to the international nomenclature must be indicated. In order for us to consider the folding pattern further, let us first give a brief description of these factors.

A. Plasma clotting factors .

I. Fibrin and fibrinogen . Fibrin is the end product of the blood clotting reaction. The coagulation of fibrinogen, which is its biological feature, occurs not only under the influence of a specific enzyme - thrombin, but can be caused by the venoms of some snakes, papain and other chemicals. Plasma contains 2-4 g/l. Place of formation: reticuloendothelial system, liver, bone marrow.

II. Thrombin and prothrombin . Only traces of thrombin are normally found in circulating blood. Its molecular weight is half the molecular weight of prothrombin and is equal to 30 thousand. The inactive precursor of thrombin - prothrombin - is always present in the circulating blood. This is a glycoprotein consisting of 18 amino acids. Some researchers believe that prothrombin is a complex compound of thrombin and heparin. Whole blood contains 15-20 mg% prothrombin. This content in excess is enough to convert all fibrinogen in the blood into fibrin.

The level of prothrombin in the blood is a relatively constant value. Among the factors that cause fluctuations in this level, menstruation (increases) and acidosis (decreases) should be pointed out. Taking 40% alcohol increases the prothrombin content by 65-175% after 0.5-1 hour, which explains the tendency to thrombosis in people who regularly drink alcohol.

In the body, prothrombin is constantly used and synthesized at the same time. Antihemorrhagic vitamin K plays an important role in its formation in the liver. It stimulates the activity of liver cells that synthesize prothrombin.

III.Thromboplastin . This factor is not present in active form in the blood. It is formed when blood cells and tissues are damaged and can be, respectively, blood, tissue, erythrocyte, platelet. Its structure is a phospholipid, similar to the phospholipids of cell membranes. According to tissue thromboplastic activity various organs They are arranged in descending order in this order: lungs, muscles, heart, kidneys, spleen, brain, liver. Sources of thromboplastin are also human milk and amniotic fluid. Thromboplastin is involved as an essential component in the first phase of blood coagulation.

IV. Ionized calcium, Ca++. The role of calcium in the process of blood clotting was known to Schmidt. It was then that they were offered sodium citrate as a blood preservative - a solution that bound Ca++ ions in the blood and prevented its clotting. Calcium is necessary not only for the conversion of prothrombin to thrombin, but for other intermediate stages of hemostasis, in all phases of coagulation. The content of calcium ions in the blood is 9-12 mg%.

V and VI.Proaccelerin and accelerin (AS-globulin ). Formed in the liver. Participates in the first and second phases of coagulation, while the amount of proaccelerin decreases and accelerin increases. Essentially V is a precursor to factor VI. Activated by thrombin and Ca++. It is an accelerator of many enzymatic coagulation reactions.

VII.Proconvertin and convertin . This factor is a protein found in the beta globulin fraction of normal plasma or serum. Activates tissue prothrombinase. Vitamin K is required for the synthesis of proconvertin in the liver. The enzyme itself becomes active upon contact with damaged tissues.

VIII.Antihemophilic globulin A (AGG-A ). Participates in the formation of blood prothrombinase. Capable of providing clotting of blood that has not had contact with tissues. The absence of this protein in the blood causes the development of genetically determined hemophilia. It has now been obtained in dry form and is used in the clinic for its treatment.

IX.Antihemophilic globulin B (AGG-B, Christmas factor , plasma component of thromboplastin). Participates in the coagulation process as a catalyst, and is also part of the blood thromboplastic complex. Promotes activation of X factor.

X.Koller factor, Steward-Prower factor . The biological role is reduced to participation in the formation of prothrombinase, since it is its main component. When rolled up it is disposed of. Named (like all other factors) after the names of patients in whom a form of hemophilia was first discovered, associated with the absence of the specified factor in their blood.

XI.Rosenthal factor, plasma thromboplastin precursor (PPT) ). Participates as an accelerator in the formation of active prothrombinase. Refers to beta globulins in the blood. Reacts in the first stages of phase 1. Formed in the liver with the participation of vitamin K.

XII.Contact factor, Hageman factor . Plays the role of a trigger in blood clotting. Contact of this globulin with a foreign surface (roughness of the vessel wall, damaged cells, etc.) leads to activation of the factor and initiates the entire chain of coagulation processes. The factor itself is adsorbed on the damaged surface and does not enter the bloodstream, thereby preventing the generalization of the coagulation process. Under the influence of adrenaline (under stress), it is partially able to activate directly in the bloodstream.

XIII.Fibrin stabilizer Lucky-Loranda . Necessary for the formation of terminally insoluble fibrin. This is a transpeptidase that cross-links individual fibrin strands with peptide bonds, promoting its polymerization. Activated by thrombin and Ca++. In addition to plasma, it is found in formed elements and tissues.

The 13 factors described are the generally accepted basic components necessary for the normal blood clotting process. The various forms of bleeding caused by their absence belong to different types of hemophilia.

IN. Cellular factors coagulation.

Along with plasma factors, cellular factors released from blood cells also play a primary role in blood coagulation. Most of them are found in platelets, but they are also found in other cells. It’s just that during hemocoagulation, platelets are destroyed in greater quantities than, say, erythrocytes or leukocytes, so platelet factors are of greatest importance in coagulation. These include:

1f.AC platelet globulin . Similar to V-VI blood factors, performs the same functions, accelerating the formation of prothrombinase.

2f.Thrombin accelerator . Accelerates the action of thrombin.

3f.Thromboplastic or phospholipid factor . It is found in granules in an inactive state and can only be used after platelets have been destroyed. Activated upon contact with blood, necessary for the formation of prothrombinase.

4f.Antiheparin factor . Binds heparin and delays its anticoagulant effect.

5f.Platelet fibrinogen . Necessary for the aggregation of blood platelets, their viscous metamorphosis and the consolidation of the platelet plug. Found both inside and outside the platelet. promotes their gluing.

6f.Retractozyme . Provides compaction of the blood clot. Several substances are determined in its composition, for example thrombostenin + ATP + glucose.

7f.Antifibinosilin . Inhibits fibrinolysis.

8f.Serotonin . Vasoconstrictor. Exogenous factor, 90% is synthesized in the gastrointestinal mucosa, the remaining 10% in platelets and the central nervous system. Released from cells when they are destroyed, it promotes spasm of small vessels, thereby helping to prevent bleeding.

In total, up to 14 factors are found in platelets, such as antithromboplastin, fibrinase, plasminogen activator, AC globulin stabilizer, platelet aggregation factor, etc.

Other blood cells contain mainly these same factors, but normally they do not play a significant role in hemocoagulation.

WITH.Tissue coagulation factors

Participate in all phases. These include active thromboplastic factors like plasma factors III, VII, IX, XII, and XIII. Tissues contain activators of factors V and VI. There is a lot of heparin, especially in the lungs, prostate gland, and kidneys. There are also antiheparin substances. For inflammatory and cancer diseases their activity increases. There are many activators (kinins) and inhibitors of fibrinolysis in tissues. The substances contained in the vascular wall are especially important. All these compounds constantly flow from the walls of blood vessels into the blood and regulate coagulation. The tissues also ensure the removal of coagulation products from the vessels.

16. Blood coagulation system, blood coagulation factors (plasma and platelet) Factors that maintain the fluid state of blood.

The function of blood is possible when it is transported through blood vessels. Damage to the blood vessels could cause bleeding. Blood can perform its functions in a liquid state. Blood can form a clot. This will block blood flow and lead to blockage of blood vessels. Causes their necrosis - heart attack, necrosis - consequences of intravascular thrombus. For normal function of the circulatory system, it must have liquid properties, but if damaged, it must have coagulation properties. Hemostasis is a series of sequential reactions that stop or reduce bleeding. These reactions include -

1. Compression and narrowing of damaged vessels
2. Lamellar thrombus formation
3. Blood coagulation, blood clot formation.
4. Thrombus retraction and lysis (dissolution)

The first reaction - compression and narrowing - occurs due to contraction of muscle elements, due to the release chemical substances. Endothelial cells (in capillaries) stick together and close the lumen. In larger cells with smooth muscle elements, depolarization occurs. The tissues themselves can react and compress the vessel. The area around the eyes has very faint elements. They compress the vessel very well during childbirth. Vasoconstriction is caused by serotonin, adrenaline, fibrinopeptide B, thromboxane A2. This primary reaction improves bleeding. Formation of a plate thrombus (associated with the function of platelets) Platelets are non-nuclear elements and have a flat shape. Diameter - 2-4 microns, thickness - 0.6-1.2 microns, volume 6-9 femtol. Quantity 150-400*10 in 9 l. They are formed from megakaryocytes by detachment. Life expectancy is 8-10 days. Electron microscopy of platelets made it possible to establish that these cells have a complex structure, despite their small size. On the outside, the platelet is covered with a thrombotic membrane containing glycoproteins. Glycoproteins form receptors that can interact with each other. The platelet membrane has invaginations that increase the area. These membranes contain tubules for secreting substances from the inside. Phosphomembranes are very important. Lamellar factor from membrane phospholipids. Under the membrane there are dense tubes - the remains of the sarcoplasmic reticulum with calcium. Under the membrane there are also microtubules and filaments of actin and myosin, which maintain the shape of platelets. Inside platelets there are mitochondria and dense dark granules and alpha granules - light. In platelets, there are 2 types of granules containing bodies.

In dense - ADP, serotonin, calcium ions

Light (alpha) - fibrinogen, von Willebrand factor, plasma factor 5, antiheparin factor, lamellar factor, beta-thromboglobulin, thrombospondin and lamellar growth factor.

The plates also have lysosomes and glycogen granules.

When vessels are damaged, the plates take part in aggregation processes and the formation of a plate thrombus. This reaction is due to a number of properties inherent in the plate - When the vessels are damaged, subendothelial proteins are exposed - adhesion (the ability to stick to these proteins due to receptors on the plate. Von Willebranca factor also contributes to adhesion). In addition to the properties of adhesion, platelets have the ability to change their shape and - release active substances (Thromboxane A2, serotonin, ADP, membrane phospholipids - lamellar factor 3, thrombin is released - coagulation - thrombin), aggregation (sticking to each other) is also characteristic. These processes lead to the formation of a plate thrombus, which can stop bleeding. The formation of prostaglandins plays an important role in these reactions. From membrane phospholipyls - arachidonic acid is formed (under the action of phospholipase A2), - Prostaglandins 1 and 2 (under the action of cyclooxygenase). First formed in the prostate gland in men. - They are converted into thromboxane A2, which suppresses adenylate cyclase and increases the content of calcium ions - aggregation occurs (lamella sticking together). Prostocyclin is formed in the vascular endothelium - it activates adenylate cyclase, reduces calcium, and this inhibits aggregation. The use of aspirin reduces the formation of thromboxane A2 without affecting prostacyclin.

Clotting factors that lead to the formation of a blood clot. The essence of the blood coagulation process is the conversion of soluble plasma protein fibrinogen into insoluble fibrin under the action of the protease thrombin. This is the final stage of blood clotting. In order for this to happen, the action of the blood coagulation system is necessary, which includes blood coagulation factors and they are divided into plasma (13 factors) and plate factors. The coagulation system also includes antifactors. All factors are in an inactive state. In addition to the coagulation system, there is a fibrinolytic system - dissolution of the formed blood clot .

Plasma coagulation factors -

1. Fibrinogen, is a unit of fibrin polymer with a concentration of 3000 mg/l

2. Prothrombin 1000 - Protease

3. Tissue thromboplastin - cofactor (released when cells are damaged)

4. Ionized calcium 100 - cofactor

5. Proaccelerin 10 - cofactor (active form - accelerin)

7. Proconvertin 0.5 - protease

8. Antihemophilic globulin A 0.1 - cofactor. Connected to the Willibring factor

9. Christmas factor 5 - protease

10. Stewart-Prover factor 10 - protease

11. Plasma precursor of thromboplastin (Rosenthal factor) 5 - protease. Its absence leads to hemophilia type C

12. Hageman factor 40 - proteases. This is where the coagulation process begins.

13. Fibrin stabilizing factor 10 - transamidase

Without numbers

Prekallikrein (Fletcher factor) 35 - protease

Kininogen with a high MB factor (Fitzgerald factor.) - 80 - cofactor

Platelet phospholipids

These factors include clotting factor inhibitors, which prevent the onset of a blood clotting reaction. The smooth wall of blood vessels is of great importance; the endothelium of blood vessels is covered with a thin film of heparin, which is an anticoagulant. Inactivation of products that are formed during blood clotting - thrombin (10 ml is enough to clot all the blood in the body). There are mechanisms in the blood that prevent this effect of thrombin. Phagocytic function of the liver and some other organs that are capable of absorbing thromboplastin 9, 10 and 11 factors. The concentration of blood clotting factors is reduced by constant blood flow. All this inhibits the formation of thrombin. The already formed thrombin is absorbed by fibrin threads, which are formed during blood clotting (they absorb thrombin). Fibrin is antithrombin 1. Another antithrombin 3 inactivates the formed thrombin and its activity increases with the combined action of heparin. This complex inactivates factors 9, 10, 11, 12. The resulting thrombin binds to thrombomodulin (located on endothelial cells). As a result, the thrombomodulin-thrombin complex promotes the conversion of protein C into the active protein form. Protein S acts together with protein C. They inactivate blood clotting factors 5 and 8. For their formation, these proteins (C and S) require the supply of vitamin K. Through the activation of protein C, the fibrinolytic system opens in the blood, which is designed to dissolve a blood clot that has formed and completed its task. The fibrinolytic system includes factors that activate and inhibit this system. In order for the process of blood dissolution to take place, activation of plasminogen is necessary. Plasminogen activators are tissue plasminogen activator, which is also in an inactive state and plasminogen can activate active factor 12, kallikrein, high molecular weight kininogen and the enzymes urokinase and streptokinase.

To activate tissue plasminogen activator, the interaction of thrombin with thrombomodulin, which is an activator of protein C, is necessary, and activated protein C activates tissue plasminogen activator and it converts plasminogen into plasmin. Plasmin ensures fibrin lysis (transforms insoluble filaments into soluble ones)

Physical activity and emotional factors lead to the activation of plasminogen. During childbirth, sometimes a large amount of thrombin can also be activated in the uterus; this condition can lead to threatening uterine bleeding. Large amounts of plasmin can act on fibrinogen, reducing its content in plasma. Increased plasmin content in venous blood, which also promotes blood flow. IN venous vessels there are conditions for the dissolution of the blood clot. Currently, plasminogen activator drugs are used. This is important in case of myocardial infarction, which will prevent necrosis of the area. In clinical practice, drugs are used that are prescribed to prevent blood clotting - anticoagulants, and anticoagulants are divided into a group of direct action and indirect action. The first group (direct) includes lemon salts and oxalic acid- sodium citrate and sodium oxalate, which bind calcium ions. You can restore it by adding potassium chloride. Hirudin (leeches) is an antithrombin, capable of inactivating thrombin, so leeches are widely used in medicinal purposes. Heparin is also prescribed as a drug to prevent blood clotting. Heparin is also included in numerous ointments and creams.

Indirect anticoagulants include vitamin K antagonists (in particular, drugs obtained from clover - dicoumarin). When dicoumarin is introduced into the body, the synthesis of vitamin K-dependent factors is disrupted (2,7,9,10). In children, when the microflora is not sufficiently developed, blood clotting processes occur.

17. Stopping bleeding in small vessels. Primary (vascular-platelet) hemostasis, its characteristics.

Vascular-platelet hemostasis is reduced to the formation of a platelet plug, or platelet thrombus. Conventionally, it is divided into three stages: 1) temporary (primary) vasospasm; 2) formation of a platelet plug due to adhesion (attachment to the damaged surface) and aggregation (sticking together) of platelets; 3) retraction (contraction and compaction) of the platelet plug.

Immediately after injury there is primary spasm of blood vessels, due to which bleeding may not occur in the first seconds or may be limited. Primary vascular spasm is caused by the release of adrenaline and norepinephrine into the blood in response to painful stimulation and lasts no more than 10-15 seconds. In the future comes secondary spasm caused by the activation of platelets and the release of vasoconstrictor agents into the blood - serotonin, TxA 2, adrenaline, etc.

Damage to blood vessels is accompanied by immediate activation of platelets, which is due to the appearance of high concentrations of ADP (from collapsing red blood cells and injured vessels), as well as exposure of the subendothelium, collagen and fibrillar structures. As a result, secondary receptors “open” and optimal conditions are created for adhesion, aggregation and formation of a platelet plug.

Adhesion is due to the presence in plasma and platelets of a special protein - von Willebrand factor (FW), which has three active centers, two of which bind to expressed platelet receptors, and one to receptors of the subendothelium and collagen fibers. Thus, with the help of FW, the platelet becomes “suspended” to the injured surface of the vessel.

Simultaneously with adhesion, platelet aggregation occurs, carried out with the help of fibrinogen, a protein contained in plasma and platelets and forming connecting bridges between them, which leads to the appearance of a platelet plug.

A complex of proteins and polypeptides called “integrins” plays an important role in adhesion and aggregation. The latter serve as binding agents between individual platelets (when sticking to each other) and the structures of the damaged vessel. Platelet aggregation can be reversible (following aggregation comes disaggregation, i.e., disintegration of aggregates), which depends on an insufficient dose of the aggregating (activating) agent.

From platelets that have undergone adhesion and aggregation, granules and the biologically active compounds they contain are intensively secreted - ADP, adrenaline, norepinephrine, factor P4, TxA2, etc. (this process is called the release reaction), which leads to secondary, irreversible aggregation. Simultaneously with the release of platelet factors, thrombin is formed, which sharply increases aggregation and leads to the appearance of a fibrin network in which individual erythrocytes and leukocytes get stuck.

Thanks to the contractile protein thrombostenin, platelets are pulled towards each other, the platelet plug contracts and thickens, i.e. retraction.

Normally, stopping bleeding from small vessels takes 2-4 minutes.

An important role for vascular platelet hemostasis is played by arachidonic acid derivatives - prostaglandin I 2 (PgI 2), or prostacyclin, and TxA 2. While maintaining the integrity of the endothelial cover, the action of Pgl prevails over TxA 2, due to which adhesion and aggregation of platelets is not observed in the vascular bed. When the endothelium is damaged at the site of injury, Pgl synthesis does not occur, and then the influence of TxA 2 manifests itself, leading to the formation of a platelet plug.

18. Secondary hemostasis, hemocoagulation. Phases of hemocoagulation. External and internal path activation of the blood clotting process. Composition of a blood clot.

Let's now try to combine into one common system we will analyze all the coagulation factors modern scheme hemostasis.

The chain reaction of blood coagulation begins from the moment blood comes into contact with the rough surface of a wounded vessel or tissue. This causes activation of plasma thromboplastic factors and then the gradual formation of two prothrombinases, clearly different in their properties - blood and tissue - occurs.

However, before the chain reaction of prothrombinase formation ends, processes associated with the participation of platelets (the so-called vascular-platelet hemostasis). Due to their ability to adhesion, platelets stick to the damaged area of ​​the vessel, stick to each other, sticking together with platelet fibrinogen. All this leads to the formation of the so-called. lamellar thrombus (“Gayem’s platelet hemostatic nail”). Platelet adhesion occurs due to ADP released from the endothelium and erythrocytes. This process is activated by wall collagen, serotonin, factor XIII and contact activation products. At first (within 1-2 minutes) blood still passes through this loose plug, but then the so-called viscose degeneration of the blood clot, it thickens and the bleeding stops. It is clear that such an end to events is possible only when small vessels are injured, where arterial pressure unable to squeeze out this “nail”.

1st coagulation phase . During the first phase of coagulation, education phase prothrombinase, there are two processes that occur at different speeds and have different meanings. This is the process of formation of blood prothrombinase, and the process of formation of tissue prothrombinase. The duration of phase 1 is 3-4 minutes. however, the formation of tissue prothrombinase takes only 3-6 seconds. The amount of tissue prothrombinase produced is very small, it is not enough to convert prothrombin into thrombin, however, tissue prothrombinase acts as an activator of a number of factors necessary for the rapid formation of blood prothrombinase. In particular, tissue prothrombinase leads to the formation of a small amount of thrombin, which converts internal coagulation factors V and VIII into an active state. A cascade of reactions ending in the formation of tissue prothrombinase ( external mechanism of hemocoagulation), as follows:

1. Contact of destroyed tissues with blood and activation of factor III - thromboplastin.

2. III factor translates VII to VIIa(proconvertin to convertin).

3. A complex is formed (Ca++ + III + VIIIa)

4. This complex activates a small amount of X factor - X goes to Ha.

5. (Ha + III + Va + Ca) form a complex that has all the properties of tissue prothrombinase. The presence of Va (VI) is due to the fact that there are always traces of thrombin in the blood, which activates V factor.

6. The resulting small amount of tissue prothrombinase converts a small amount of prothrombin into thrombin.

7. Thrombin activates a sufficient amount of V and VIII factors necessary for the formation of blood prothrombinase.

If this cascade is turned off (for example, if, with all precautions using paraffin needles, you take blood from a vein, preventing its contact with tissues and with a rough surface, and place it in a paraffin tube), the blood clots very slowly, within 20-25 minutes or longer.

Well, normally, simultaneously with the process already described, another cascade of reactions associated with the action of plasma factors is launched, ending with the formation of blood prothrombinase in an amount sufficient to convert a large amount of prothrombin from thrombin. These reactions are as follows ( interior mechanism of hemocoagulation):

1. Contact with a rough or foreign surface leads to the activation of factor XII: XII - XIIa. At the same time, a Gayem hemostatic nail begins to form (vascular-platelet hemostasis).

2. Active factor XII converts factor XI into an active state and a new complex is formed XIIa +Ca++ +XIa+ III(f3)

3. Under the influence of the specified complex, factor IX is activated and a complex is formed IXa + Va + Ca++ +III(f3).

4. Under the influence of this complex, a significant amount of X factor is activated, after which the last complex of factors is formed in large quantities: Xa + Va + Ca++ + III(ph3), which is called blood prothrombinase.

This entire process normally takes about 4-5 minutes, after which the coagulation moves into the next phase.

2 coagulation phase - thrombin generation phase lies in the fact that under the influence of the enzyme prothrombinase, factor II (prothrombin) goes into an active state (IIa). This is a proteolytic process, the prothrombin molecule is split into two halves. The resulting thrombin goes to the implementation of the next phase, and is also used in the blood to activate more and more accelerin (V and VI factors). This is an example of a system with positive feedback. The thrombin generation phase lasts several seconds.

3rd phase of coagulation - fibrin formation phase- also an enzymatic process, as a result of which a piece of several amino acids is split off from fibrinogen due to the action of the proteolytic enzyme thrombin, and the remainder is called fibrin monomer, which in its properties differs sharply from fibrinogen. In particular, it is capable of polymerization. This connection is designated as Im.

4 coagulation phase - fibrin polymerization and clot organization. It also has several stages. Initially, in a few seconds, under the influence of blood pH, temperature, and ionic composition of the plasma, long fibrin polymer filaments are formed Is which, however, is not yet very stable, since it can dissolve in urea solutions. Therefore, at the next stage, under the influence of the fibrin stabilizer Lucky-Loranda ( XIII factor) fibrin is finally stabilized and converted into fibrin Ij. It falls out of solution in the form of long threads that form a network in the blood, in the cells of which cells get stuck. Blood changes from a liquid state to a jelly-like state (coagulates). The next stage of this phase is the retraction (compaction) of the clot, which lasts quite a long time (several minutes), which occurs due to the contraction of fibrin threads under the influence of retractozyme (thrombostenin). As a result, the clot becomes dense, the serum is squeezed out of it, and the clot itself turns into a dense plug that blocks the vessel - a thrombus.

5 coagulation phase - fibrinolysis. Although it is not actually associated with the formation of a blood clot, it is considered the last phase of hemocoagulation, since during this phase the thrombus is limited to only the area where it is actually needed. If the thrombus has completely closed the lumen of the vessel, then during this phase this lumen is restored (there is thrombus recanalization). In practice, fibrinolysis always occurs in parallel with the formation of fibrin, preventing the generalization of coagulation and limiting the process. Fibrin dissolution is ensured by a proteolytic enzyme plasmin (fibrinolysin) which is contained in plasma in an inactive state in the form plasminogen (profibrinolysine). The transition of plasminogen to the active state is carried out by a special activator, which in turn is formed from inactive precursors ( proactivators), released from tissues, vessel walls, blood cells, especially platelets. In the processes of transferring proactivators and plasminogen activators into an active state, acid and alkaline blood phosphatases, cell trypsin, tissue lysokinases, kinins, environmental reaction, and factor XII play an important role. Plasmin breaks down fibrin into individual polypeptides, which are then utilized by the body.

Normally, a person’s blood begins to clot within 3-4 minutes after leaving the body. After 5-6 minutes it completely turns into a jelly-like clot. You will learn how to determine bleeding time, blood clotting rate and prothrombin time in practical classes. All of them have important clinical significance.

19. Fibrinolytic system of the blood, its significance. Retraction of a blood clot.

Prevents blood clotting and fibrinolytic blood system. According to modern ideas, it consists of profibrinolysin (plasminogen), proactivator and plasma and tissue systems plasminogen activators. Under the influence of activators, plasminogen transforms into plasmin, which dissolves the fibrin clot.

Under natural conditions, the fibrinolytic activity of the blood depends on the plasminogen depot, the plasma activator, on the conditions that ensure activation processes, and on the entry of these substances into the blood. Spontaneous activity of plasminogen in healthy body observed in a state of excitement, after an injection of adrenaline, with physical stress and in conditions associated with shock. Among artificial blockers of fibrinolytic activity of the blood, gamma aminocaproic acid (GABA) occupies a special place. Normally, plasma contains an amount of plasmin inhibitors that is 10 times greater than the level of plasminogen reserves in the blood.

The state of hemocoagulation processes and the relative constancy or dynamic balance of coagulation and anticoagulation factors is associated with the functional state of the organs of the hemocoagulation system (bone marrow, liver, spleen, lungs, vascular wall). The activity of the latter, and consequently the state of the hemocoagulation process, is regulated by neurohumoral mechanisms. Blood vessels have special receptors that sense the concentration of thrombin and plasmin. These two substances program the activity of these systems.

20. Anticoagulants of direct and indirect action, primary and secondary.

Despite the fact that the circulating blood contains all the factors necessary for the formation of a blood clot, under natural conditions, in the presence of vascular integrity, the blood remains liquid. This is due to the presence in the bloodstream of anticoagulants, called natural anticoagulants, or the fibrinolytic component of the hemostasis system.

Natural anticoagulants are divided into primary and secondary. Primary anticoagulants are always present in the circulating blood, secondary anticoagulants are formed as a result of proteolytic cleavage of blood coagulation factors during the formation and dissolution of a fibrin clot.

Primary anticoagulants can be divided into three main groups: 1) antithromboplastins - having antithromboplastic and antiprothrombinase effects; 2) antithrombins - binding thrombin; 3) inhibitors of fibrin self-assembly - allowing the transition of fibrinogen to fibrin.

It should be noted that when the concentration of primary natural anticoagulants decreases, favorable conditions are created for the development of thrombosis and disseminated intravascular coagulation syndrome.

MAIN NATURAL ANTICOAGULANTS (according to Barkagan 3.S. and Bishevsky K.M.)

To secondary anticoagulants include “spent” blood coagulation factors (participated in coagulation) and degradation products of fibrinogen and fibrin (FDP), which have a powerful antiaggregation and anticoagulation effect, as well as stimulating fibrinolysis. The role of secondary anticoagulants is reduced to limiting intravascular coagulation and the spread of thrombus through the vessels.

21. Blood groups, their classification, significance in blood transfusion.

The doctrine of blood groups arose from the needs clinical medicine. When transfusing blood from animals to humans or from humans to humans, doctors often observed severe complications, sometimes ending in the death of the recipient (the person to whom the blood was transfused).

With the discovery of blood groups by the Viennese physician K. Landsteiner (1901), it became clear why in some cases blood transfusions are successful, while in others they end tragically for the patient. K. Landsteiner was the first to discover that the plasma, or serum, of some people is capable of agglutinating (gluing together) the red blood cells of other people. This phenomenon is called isohemagglutination. It is based on the presence in erythrocytes of antigens called agglutinogens and designated by the letters A and B, and in plasma - natural antibodies, or agglutinins, called α And β . Agglutination of erythrocytes is observed only if the same agglutinogen and agglutinin are found: A and α , In and β .

It has been established that agglutinins, being natural antibodies (AT), have two binding centers, and therefore one agglutinin molecule is able to form a bridge between two erythrocytes. In this case, each of the erythrocytes can, with the participation of agglutinins, contact the neighboring one, due to which a conglomerate (agglutinate) of erythrocytes appears.

There cannot be agglutinogens and agglutinins of the same name in the blood of the same person, since otherwise there would be a massive gluing of red blood cells, which is incompatible with life. Only four combinations are possible in which the same agglutinogens and agglutinins, or four blood groups, do not occur: I - αβ , II - Aβ , III - B α , IV - AB.

In addition to agglutinins, plasma or serum of blood contains hemolysins: there are also two types of them and they are designated, like agglutinins, by the letters α And β . When the same agglutinogen and hemolysin meet, hemolysis of red blood cells occurs. The effect of hemolysins manifests itself at a temperature of 37-40 o WITH. That is why, when transfusion of incompatible blood occurs in a person, within 30-40 seconds. hemolysis of red blood cells occurs. At room temperature, if agglutinogens and agglutinins of the same name occur, agglutination occurs, but hemolysis is not observed.

In the plasma of people with blood groups II, III, IV there are antiagglutinogens that have left the erythrocyte and tissues. They are designated, like agglutinogens, by the letters A and B (Table 6.4).

Table 6.4. Serological composition of the main blood groups (ABO system)

As can be seen from the table below, blood group I does not have agglutinogens, and therefore, according to the international classification, it is designated as group 0, II is called A, III - B, IV - AB.

To resolve the issue of blood group compatibility, the following rule is used: the recipient’s environment must be suitable for the life of the donor’s red blood cells (the person who donates blood). Plasma is such a medium; therefore, the recipient must take into account the agglutinins and hemolysins found in the plasma, and the donor must take into account the agglutinogens contained in erythrocytes. To resolve the issue of blood group compatibility, the blood being tested is mixed with serum obtained from people with different blood groups (Table 6.5).

Table 6.5. Compatibility various groups blood

Note. “+” - presence of agglutination (groups are incompatible); “--” – absence of agglutination (groups are compatible.

The table shows that agglutination occurs when group I serum is mixed with erythrocytes of groups II, III and IV, group II serum is mixed with erythrocytes of groups III and IV, group III serum is mixed with erythrocytes of groups II and IV.

Consequently, blood group I is compatible with all other blood groups, therefore a person with blood group I is called universal donor. On the other hand, red blood cells of blood group IV should not give an agglutination reaction when mixed with plasma (serum) of people with any blood group, therefore people with blood group IV are called universal recipients.

Why, when deciding on compatibility, do they not take into account the donor’s agglutinins and hemolysins? This is explained by the fact that agglutinins and hemolysins, when transfused with small doses of blood (200-300 ml), are diluted in a large volume of plasma (2500-2800 ml) of the recipient and are bound by its antiagglutinins, and therefore should not pose a danger to red blood cells.

IN everyday practice To resolve the issue of the type of blood to be transfused, a different rule is used: blood of the same type should be transfused and only for health reasons, when a person has lost a lot of blood. Only in the absence of single-group blood can a small amount of compatible blood of a different group be transfused with great care. This is explained by the fact that approximately 10-20% of people have a high concentration of very active agglutinins and hemolysins, which cannot be bound by antiagglutinins even in the case of transfusion of a small amount of blood of a different group.

Post-transfusion complications sometimes arise due to errors in determining blood groups. It has been established that agglutinogens A and B exist in different variants, differing in their structure and antigenic activity. Most of them received a digital designation (A 1, A, 2, A 3, etc., B 1, B 2, etc.). The higher the serial number of the agglutinogen, the less activity it exhibits. Although agglutinogen types A and B are relatively rare, they may not be detected when determining blood groups, which can lead to transfusion of incompatible blood.

It should also be taken into account that the majority of human erythrocytes carry antigen H. This antigen is always found on the surface of cell membranes in people with blood group 0, and is also present as a latent determinant on the cells of people with blood groups A, B and AB. H is the antigen from which antigens A and B are formed. In people with blood group I, the antigen is accessible to the action of anti-H antibodies, which are quite common in people with blood groups II and IV and relatively rare in people with group III. This circumstance can cause blood transfusion complications when blood of group 1 is transfused to people with other blood groups.

The concentration of agglutinogens on the surface of the erythrocyte membrane is extremely high. Thus, one erythrocyte of blood group A 1 contains on average 900,000-1,700,000 antigenic determinants, or receptors, for agglutinins of the same name. With an increase in the serial number of the agglutinogen, the number of such determinants decreases. Group A 2 erythrocytes have only 250,000–260,000 antigenic determinants, which also explains the lower activity of this agglutinogen.

Currently, the AB0 system is often referred to as AVN, and the terms “antigens” and “antibodies” are used instead of the terms “agglutinogens” and “agglutinins” (for example, AVN antigens and AVN antibodies).

22. Rh factor, its significance.

K. Landsteiner and A. Wiener (1940) discovered rhesus AG in the erythrocytes of the rhesus macaque monkey, which they called Rh factor. It later turned out that approximately 85% of people of the white race also have this hypertension. Such people are called Rh positive (Rh +). About 15% of people do not have this hypertension and are called Rh negative (Rh).

It is known that the Rh factor is a complex system that includes more than 40 antigens, designated by numbers, letters and symbols. The most common Rh antigens are type D (85%), C (70%), E (30%), e (80%) - they also have the most pronounced antigenicity. The Rh system does not normally have the same ag-glutinins, but they can appear if Rh-positive blood is transfused into a Rh-negative person.

The Rh factor is inherited. If the woman is Rh and the man is Rh +, then the fetus in 50-100% of cases will inherit the Rh factor from the father, and then the mother and the fetus will be incompatible for the Rh factor. It has been established that during such a pregnancy the placenta has increased permeability to the red blood cells of the fetus. The latter, penetrating into the mother’s blood, lead to the formation of antibodies (anti-resus agglutinins). Penetrating into the blood of the fetus, antibodies cause agglutination and hemolysis of its red blood cells.

The most severe complications that arise from transfusion of incompatible blood and Rh conflict are caused not only by the formation of erythrocyte conglomerates and their hemolysis, but also by intense intravascular coagulation, since erythrocytes contain a set of factors that cause platelet aggregation and formation of fibrin clots. In this case, all organs suffer, but the kidneys are especially severely damaged, since clots clog the “wonderful network” of the glomerulus of the kidney, preventing the formation of urine, which may be incompatible with life.

According to modern concepts, the erythrocyte membrane is considered as a set of very different antigens, of which there are more than 500. More than 400 million combinations, or group characteristics of blood, can be made from these antigens alone. If we take into account all the other antigens found in the blood, then the number of combinations will reach 700 billion, i.e., significantly more than there are people on the globe. Of course, not all hypertension are important for clinical practice. However, when blood is transfused with relatively rare hypertension, severe transfusion complications and even death of the patient can occur.

Serious complications often occur during pregnancy, including severe anemia, which can be explained by the incompatibility of blood groups according to the systems of little-studied antigens of the mother and fetus. In this case, not only the pregnant woman suffers, but the unborn child is also in unfavorable conditions. Incompatibility of mother and fetus by blood groups can cause miscarriages and premature births.

Hematologists identify the most important antigenic systems: ABO, Rh, MNSs, P, Lutheran (Lu), Kell-Kellano (Kk), Lewis (Le), Duffy (Fy) and Kid (Jk). These antigen systems are taken into account in forensic medicine to establish paternity and sometimes during organ and tissue transplantation.

Currently, whole blood transfusions are performed relatively rarely, since they use the transfusion of various blood components, i.e., they transfuse what the body needs most: plasma or serum, red blood cells, leukocytes or platelets. In such a situation, a smaller amount of antigens is introduced, which reduces the risk of post-transfusion complications.

23. Formation, life expectancy and destruction of blood cells, Erythropoiesis. leukopoiesis, thrombocytopoiesis. Regulation of hematopoiesis.

Hematopoiesis (hematopoiesis) is a complex process of formation, development and maturation of blood cells. Hematopoiesis occurs in special hematopoietic organs. The part of the body's hematopoietic system that is directly involved in the production of red blood cells is called erythron. Erythron is not a single organ, but is scattered throughout the hematopoietic tissue of the bone marrow.

According to modern concepts, the single mother cell of hematopoiesis is the precursor cell ( stem cell), from which erythrocytes, leukocytes, lymphocytes, and platelets are formed through a series of intermediate stages.

Red blood cells are formed intravascularly (inside the vessel) in the sinuses of the red bone marrow. Red blood cells entering the blood from the bone marrow contain a basophilic substance that is stained with basic dyes. These cells are called reticulocytes. The content of reticulocytes in the blood of a healthy person is 0.2-1.2%. The lifespan of red blood cells is 100-120 days. Red blood cells in the cells of the macrophage system are destroyed.

Leukocytes are formed extravascularly (outside the vessel). In this case, granulocytes and monocytes mature in the red bone marrow, and lymphocytes in the thymus gland, lymph nodes, tonsils, adenoids, lymphatic formations of the gastrointestinal tract, and spleen. The lifespan of leukocytes is up to 15-20 days. Leukocytes die off in the cells of the macrophage system.

Platelets are formed from megakaryocyte giant cells in the red bone marrow and lungs. Like leukocytes, platelets develop outside the vessel. Penetration of blood platelets into vascular bed is ensured by amoeboid mobility and the activity of their proteolytic enzymes. The lifespan of platelets is 2-5 days, and according to some data up to 10-11 days. Blood platelets in the cells of the macrophage system are destroyed.

The formation of blood cells occurs under the control of humoral and nervous regulatory mechanisms.

The humoral components of the regulation of hematopoiesis, in turn, can be divided into two groups: exogenous and endogenous factors.

Exogenous factors include biologically active substances - B vitamins, vitamin C, folic acid, as well as microelements: iron, cobalt, copper, manganese. Specified substances, influencing enzymatic processes in the hematopoietic organs, promote the maturation and differentiation of formed elements, the synthesis of their structural (component) parts.

Endogenous factors regulating hematopoiesis include: Castle factor, hematopoietins, erythropoietins, thrombocytopoietins, leukopoietins, some hormones of the endocrine glands. Hemopoietins are products of the breakdown of formed elements (leukocytes, platelets, erythrocytes) and have a pronounced stimulating effect on the formation of blood formed elements.

24. Lymph, its composition and properties. Formations and movement of lymph.

Lymph is the fluid contained in vertebrate animals and humans in the lymphatic capillaries and vessels. The lymphatic system begins with lymphatic capillaries, which drain all tissue intercellular spaces. The movement of lymph is in one direction - towards the large veins. On this path, small capillaries merge into large lymphatic vessels, which gradually, increasing in size, form the right lymphatic and thoracic ducts. Not all lymph flows into the bloodstream through the thoracic duct, since some lymphatic trunks (right lymphatic duct, jugular, subclavian and bronchomediastinal) independently flow into the veins.

Along the lymphatic vessels there are lymph nodes, after which the lymph is again collected into slightly larger lymphatic vessels.

In fasting people, lymph is a clear or slightly opalescent fluid. The average specific gravity is 1016, the reaction is alkaline, pH - 9. The chemical composition is close to the composition of plasma, tissue fluid, as well as other biological fluids (spinal, synovial), but there are some differences and depend on the permeability of the membranes separating them from each other. The most important difference in the composition of lymph from blood plasma is its lower protein content. The total protein content on average is about half of the content in the blood.

During the digestion period, the concentration of substances absorbed from the intestines in the lymph increases sharply. In the chyle (lymph of the mesenteric vessels), the concentration of fat, to a lesser extent carbohydrates, and slightly proteins increases sharply.

The cellular composition of lymph is not exactly the same depending on whether it has passed through one or all lymph nodes or has not been in contact with them. Accordingly, peripheral and central (taken from the thoracic duct) lymph is distinguished. Peripheral lymph is much poorer in cellular elements. So, 2 mm. cube A dog's peripheral lymph contains an average of 550 leukocytes, and the central lymph contains 7800 leukocytes. In a person, in the central lymph there can be up to 20,000 leukocytes per 1 mm3. Along with lymphocytes, which make up 88%, lymph includes small quantity erythrocytes, macrophages, eosinophils, neutrophils.

The total production of lymphocytes in human lymph nodes is 3 million per 1 kg of mass/hour.

Basic functions of the lymphatic system are very diverse and mainly consist of:

Return of protein to the blood from tissue spaces;

Participating in the redistribution of fluid in the body;

In protective reactions, both by removing and destroying various bacteria, and by participating in immune reactions;

Participating in the transport of nutrients, especially fats.

(blood platelets). In an adult, formed elements of blood make up about 40-48%, and plasma - 52-60%.

Blood is a liquid tissue. It has a red color, which is given to it by erythrocytes (red blood cells). The implementation of the main functions of the blood is ensured by maintaining an optimal plasma volume, a certain level of blood cellular elements (Fig. 1) and various plasma components.

Plasma devoid of fibrinogen is called serum.

Rice. 1. Formed elements of blood: a - cattle; b - chicken; 1 - red blood cells; 2, b — eosinophilic granulocytes; 3,8,11 - lymphocytes: medium, small, large; 4 - blood platelets; 5.9 - neutrophil granulocytes: segmented (mature), band (young); 7 - basophilic granulocyte; 10 - monocyte; 12 - erythrocyte nucleus; 13 - non-granular leukocytes; 14 - granular leukocytes

All blood cells- , and - are formed in the red bone marrow. Despite the fact that all blood cells are descendants of a single hematopoietic cell - fibroblasts, they perform various specific functions, at the same time, their common origin has endowed them with common properties. Thus, all blood cells, regardless of their specificity, participate in the transport various substances, perform protective and regulatory functions.

Rice. 2. Blood composition

Red blood cells in men are 4.0-5.0x 10 12 /l, in women 3.9-4.7x 10 12 /l; leukocytes 4.0-9.0x 10 9 /l; platelets 180-320x 10 9 /l.

Red blood cells

Erythrocytes, or red blood cells, were first discovered by Malpighi in the blood of a frog (1661), and Leeuwenhoek (1673) showed that they were also present in the blood of humans and mammals.

- anucleate red blood cells of a biconcave disc shape. Thanks to this shape and the elasticity of the cytoskeleton, red blood cells can transport a large number of different substances and penetrate through narrow capillaries.

The red blood cell consists of stroma and a semipermeable membrane.

The main component of red blood cells (up to 95% of the mass) is hemoglobin, which gives the blood its red color and consists of globin protein and iron-containing heme. The main function of hemoglobin and red blood cells is the transport of oxygen (0 2) and carbon dioxide (CO 2).

There are about 25 trillion red blood cells in human blood. If you put all the red blood cells next to each other, you will get a chain about 200 thousand km long, which can encircle the globe along the equator 5 times. If you put all the red blood cells of one person on top of each other, you will get a “column” more than 60 km high.

Erythrocytes have the shape of a biconcave disk; when viewed in a cross section, they resemble dumbbells. This shape not only increases the surface of the cell, but also promotes faster and more uniform diffusion of gases across the cell membrane. If they had the shape of a ball, then the distance from the center of the cell to the surface would increase 3 times, and the total area of ​​erythrocytes would be 20% less. Red blood cells are highly elastic. They easily pass through capillaries that have half the diameter of the cell itself. The total surface of all red blood cells reaches 3000 m2, which is 1500 times greater than the surface of the human body. Such ratios of surface and volume contribute to the optimal performance of the main function of red blood cells - the transfer of oxygen from the lungs to the cells of the body.

Unlike other representatives of the chordate type, mammalian erythrocytes are anucleate cells. The loss of the nucleus led to an increase in the amount of the respiratory enzyme - hemoglobin. An aqueous red blood cell contains about 400 million hemoglobin molecules. Deprivation of the nucleus has led to the fact that the erythrocyte itself consumes 200 times less oxygen than its nuclear representatives (erythroblasts and normoblasts).

Men's blood contains an average of 5. 10 12 / l of red blood cells (5,000,000 in 1 μl), in women - about 4.5. 10 12 /l erythrocytes (4,500,000 in 1 μl).

Normally, the number of red blood cells is subject to slight fluctuations. With various diseases, the number of red blood cells may decrease. Similar condition is called erythropenia and is often accompanied by anemia or anemia. An increase in the number of red blood cells is called erythrocytosis.

Hemolysis and its causes

Hemolysis is the rupture of the red blood cell membrane and release into the plasma, due to which the blood acquires a lacquered tint. Under artificial conditions, hemolysis of erythrocytes can be caused by placing them in a hypotonic solution - osmotic hemolysis. For healthy people, the minimum limit of osmotic resistance corresponds to a solution containing 0.42-0.48% NaCl, while complete hemolysis (maximum limit of resistance) occurs at a concentration of 0.30-0.34% NaCl.

Hemolysis can be caused by chemical agents (chloroform, ether, etc.) that destroy the erythrocyte membrane - chemical hemolysis. Hemolysis often occurs in acetic acid poisoning. The venoms of some snakes have hemolyzing properties - biological hemolysis.

When the ampoule with blood is strongly shaken, destruction of the red blood cell membrane is also observed -mechanical hemolysis. It may occur in patients with prosthetics valve apparatus heart and blood vessels, and sometimes occurs when walking (marching hemoglobinuria) due to injury to red blood cells in the capillaries of the feet.

If red blood cells are frozen and then warmed up, hemolysis occurs, which is called thermal. Finally, with incompatible blood transfusion and the presence of autoantibodies to red blood cells, immune hemolysis. The latter is the cause of anemia and is often accompanied by the release of hemoglobin and its derivatives in the urine (hemoglobinuria).

Erythrocyte sedimentation rate (ESR)

If blood is placed in a test tube, after adding substances that prevent clotting, then after some time the blood will separate into two layers: the upper one consists of plasma, and the lower one consists of formed elements, mainly red blood cells. Based on these properties.

Farreus proposed studying the suspension stability of erythrocytes by determining the rate of their sedimentation in the blood, the coagulability of which was eliminated by the preliminary addition of sodium citrate. This indicator is called “erythrocyte sedimentation rate (ESR)” or “erythrocyte sedimentation reaction (ESR)”.

The ESR value depends on age and gender. Normally, in men this figure is 6-12 mm per hour, in women - 8-15 mm per hour, in older people of both sexes - 15-20 mm per hour.

The greatest influence on the ESR value is exerted by the content of fibrinogen and globulin proteins: with an increase in their concentration, the ESR increases, since the electrical charge of the cell membrane decreases and they more easily “stick together” like coin columns. ESR increases sharply during pregnancy, when the fibrinogen content in plasma increases. This is a physiological increase; it is assumed that it provides a protective function of the body during gestation. Increasing ESR observed in inflammatory, infectious and oncological diseases, as well as with a significant decrease in the number of red blood cells (anemia). A decrease in ESR in adults and children over 1 year of age is an unfavorable sign.

Leukocytes

- white blood cells. They contain a nucleus, do not have a permanent shape, have amoeboid mobility and secretory activity.

In animals, the content of leukocytes in the blood is approximately 1000 times less than erythrocytes. 1 liter of cattle blood contains approximately (6-10). 10 9 leukocytes, horses - (7-12)-10 9, pigs - (8-16)-10 9 leukocytes. The number of leukocytes in natural conditions fluctuates within wide limits and can increase after eating food, heavy muscular work, with severe irritation, pain, etc. An increase in the number of leukocytes in the blood is called leukocytosis, and a decrease is called leukopenia.

There are several types of leukocytes depending on their size, the presence or absence of granularity in the protoplasm, the shape of the nucleus, etc. Based on the presence of granularity in the cytoplasm, leukocytes are divided into granulocytes (granular) and agranulocytes (non-granular).

Granulocytes make up the majority of white blood cells and include neutrophils (stained with acidic and basic dyes), eosinophils (stained with acidic dyes) and basophils (stained with basic dyes).

Neutrophils capable of amoeboid movement, pass through the endothelium of capillaries, and actively move to the site of damage or inflammation. They phagocytose living and dead microorganisms and then digest them using enzymes. Neutrophils secrete lysosomal proteins and produce interferon.

Eosinophils neutralize and destroy toxins of protein origin, foreign proteins, antigen-antibody complexes. They produce the enzyme histaminase, absorb and destroy histamine. Their number increases when various toxins enter the body.

Basophils take part in allergic reactions, releasing heparin and histamine after encountering an allergen, which prevent blood clotting, dilate capillaries and promote resorption during inflammation. Their number increases with injuries and inflammatory processes.

Agranulocytes are divided into monocytes and lymphocytes.

Monocytes have pronounced phagocytic and bactericidal activity in an acidic environment. Participate in the formation of the immune response. Their number increases during inflammatory processes.

Carry out reactions of cellular and humoral immunity. Capable of penetrating tissue and returning back to the blood, they live for several years. They are responsible for the formation of specific immunity and carry out immune surveillance in the body, maintaining the genetic constancy of the internal environment. On the plasma membrane of lymphocytes there are specific areas - receptors, due to which they are activated upon contact with foreign microorganisms and proteins. They synthesize protective antibodies, lyse foreign cells, provide a transplant rejection reaction and the body's immune memory. Their number increases with the penetration of microorganisms into the body. Unlike other leukocytes, lymphocytes mature in the red bone marrow, but later they undergo differentiation in lymphoid organs and tissues. Some lymphocytes differentiate in the thymus (thymus gland) and are therefore called T lymphocytes.

T lymphocytes are formed in the bone marrow, enter and undergo differentiation in the thymus, and then settle in the lymph nodes, spleen and circulate in the blood. There are several forms of T-lymphocytes: T-helpers (helpers), which interact with B-lymphocytes, turning them into plasma cells that synthesize antibodies and gamma globulins; T-suppressors (suppressors), which suppress excessive reactions of B-lymphocytes and maintain a certain ratio of different forms of lymphocytes, and T-killers (killers), which interact with foreign cells and destroy them, forming cellular immunity reactions.

B lymphocytes are formed in the bone marrow, but in mammals they undergo differentiation in the lymphoid tissue of the intestine, palatine and pharyngeal tonsils. When they encounter an antigen, B lymphocytes are activated, migrate to the spleen, lymph nodes, where they multiply and transform into plasma cells that produce antibodies and gamma globulins.

Null lymphocytes do not undergo differentiation in the organs of the immune system, but, if necessary, are able to transform into B and T lymphocytes.

The number of lymphocytes increases when microorganisms penetrate the body.

The percentage of individual forms of blood leukocytes is called leukocyte formula, or leicogrammoi.

Maintaining the constancy of the leukocyte formula of peripheral blood is achieved through the interaction of continuously occurring processes of maturation and destruction of leukocytes.

Lifespan of leukocytes different types lasts from several hours to several days, with the exception of lymphocytes, some of which live for several years.

Platelets

- small blood platelets. After formation in the red bone marrow, they enter the bloodstream. Platelets have mobility, phagocytic activity, and are involved in immune reactions. When destroyed, platelets release components of the blood coagulation system, participate in blood clotting, clot retraction and lysis of the resulting fibrin. They also regulate angiotrophic function thanks to the growth factor they contain. Under the influence of this factor, the proliferation of endothelial and smooth muscle cells of blood vessels increases. Platelets have the ability to adhesion (sticking) and aggregation (the ability to stick together).

Platelets are formed and develop in the red bone marrow. Their lifespan is on average 8 days, and then they are destroyed in the spleen. The number of these cells increases with trauma and vascular damage.

1 liter of blood in a horse contains up to 500. 10 9 platelets, in cattle - 600. 10 9, in pigs - 300. 10 9 platelets.

Blood constants

Basic blood constants

Blood, as a liquid tissue of the body, is characterized by many constants, which can be divided into soft and hard.

Soft (plastic) constants can change their value from the constant level over a wide range without significant changes in the vital activity of cells and body functions. Soft blood constants include: the amount of circulating blood, the ratio of plasma volumes and formed elements, the number of formed elements, the amount of hemoglobin, erythrocyte sedimentation rate, blood viscosity, relative density of blood, etc.

The amount of blood circulating through the vessels

The total amount of blood in the body is 6-8% of body weight (4-6 l), of which about half circulates at rest in the body, the other half - 45-50% is in the depot (in the liver - 20%, in the spleen - 16%, in skin vessels - 10%).

The ratio of the volumes of blood plasma and formed elements is determined by centrifuging the blood in a hematocrit analyzer. Under normal conditions, this ratio is 45% formed elements and 55% plasma. This value in a healthy person can undergo significant and lasting changes only when adapting to high altitudes. The liquid part of the blood (plasma), devoid of fibrinogen, is called serum.

Erythrocyte sedimentation rate

For men -2-10 mm/h, for women - 2-15 mm/h. The erythrocyte sedimentation rate depends on many factors: the number of erythrocytes, their morphological characteristics, the magnitude of the charge, the ability to agglomerate (aggregate), and the protein composition of the plasma. The erythrocyte sedimentation rate is influenced by the physiological state of the body. For example, during pregnancy, inflammatory processes, emotional stress and other conditions, the erythrocyte sedimentation rate increases.

Blood viscosity

Caused by the presence of proteins and red blood cells. The viscosity of whole blood is 5, if the viscosity of water is taken as 1, and plasma - 1.7-2.2.

Specific gravity (relative density) of blood

Depends on the content of formed elements, proteins and lipids. The specific gravity of whole blood is 1.050, plasma - 1.025-1.034.

Hard constants

Their fluctuation is permissible in very small ranges, since deviation by insignificant values ​​leads to disruption of the vital activity of cells or the functions of the entire organism. Hard constants include the constancy of the ionic composition of the blood, the amount of proteins in the plasma, the osmotic pressure of the blood, the amount of glucose in the blood, the amount of oxygen and carbon dioxide in the blood, and the acid-base balance.

Constancy of blood ion composition

The total amount of inorganic substances in blood plasma is about 0.9%. These substances include: cations (sodium, potassium, calcium, magnesium) and anions (chlorine, HPO 4, HCO 3 -). The cation content is a more rigid value than the anion content.

The amount of proteins in plasma

Functions of proteins:

• create oncotic pressure of the blood, on which the exchange of water between the blood and the intercellular fluid depends;
• determine blood viscosity, which affects the hydrostatic pressure of the blood;
• fibrinogen and globulins take part in the blood clotting process;
• the ratio of albumin and globulin affects the ESR value;
• are important components of the protective function of blood (gamma globulins);
• take part in the transport of metabolic products, fats, hormones, vitamins, heavy metal salts;
• are an indispensable reserve for the construction of tissue proteins;
• participate in maintaining acid-base balance, performing buffer functions.

The total amount of proteins in plasma is 7-8%. Plasma proteins are distinguished by structure and functional properties. They are divided into three groups: albumins (4.5%), globulins (1.7-3.5%) and fibrinogen (0.2-0.4%).

Blood osmotic pressure

Understands the force with which a solute holds or attracts a solvent. This force causes the movement of solvent through a semipermeable membrane from a less concentrated solution to a more concentrated one.

The osmotic pressure of the blood is 7.6 atm. It depends on the content of salts and water in the blood plasma and ensures that it is maintained at the physiologically necessary level of concentration of various substances dissolved in the body’s fluids. Osmotic pressure promotes the distribution of water between tissues, cells and blood.

Solutions whose osmotic pressure is equal to the osmotic pressure of the cells are called isotonic, and they do not cause a change in cell volume. Solutions whose osmotic pressure is higher than the osmotic pressure of cells are called hypertonic. They cause cells to shrink as a result of the transfer of some water from the cells into the solution. Solutions with lower osmotic pressure are called hypotonic. They cause an increase in cell volume as a result of the passage of water from solution into the cell.

Minor changes in the salt composition of blood plasma can be detrimental to the cells of the body and, above all, the cells of the blood itself due to changes in osmotic pressure.

Part of the osmotic pressure created by plasma proteins is oncotic pressure, the value of which is 0.03-0.04 atm., or 25-30 mm Hg. Oncotic pressure is a factor that promotes the transfer of water from tissues into the bloodstream. When the oncotic pressure of the blood decreases, water leaks out of the vessels into the interstitial space and leads to tissue edema.

The normal amount of glucose in the blood is 3.3-5.5 mmol/l.

Content of oxygen and carbon dioxide in the blood

Arterial blood contains 18-20 volume percent oxygen and 50-52 volume percent carbon dioxide, venous blood contains 12 volume percent oxygen and 55-58 volume percent carbon dioxide.

blood pH

Active regulation of blood is determined by the ratio of hydrogen and hydroxyl ions and is a rigid constant. To assess the active reaction of the blood, a hydrogen index of 7.36 is used (in arterial blood 7.4, in venous blood - 7.35). An increase in the concentration of hydrogen ions leads to a shift in the blood reaction to the acidic side, and is called acidosis. An increase in the concentration of hydrogen ions and an increase in the concentration of hydroxyl ions (OH) leads to a shift in the reaction to the alkaline side, and is called alkalosis.

Maintaining blood constants at a certain level is carried out according to the principle of self-regulation, which is achieved by the formation of appropriate functional systems.

Blood continuously circulating in a closed system of blood vessels performs in the body essential functions: transport, respiratory, regulatory and protective. It ensures relative constancy of the internal environment of the body.

Blood is a type of connective tissue consisting of a liquid intercellular substance of complex composition - plasma and cells suspended in it - blood cells: erythrocytes (red blood cells), leukocytes (white blood cells) and platelets (blood platelets). 1 mm 3 of blood contains 4.5–5 million erythrocytes, 5–8 thousand leukocytes, 200–400 thousand platelets.

In the human body, the amount of blood is on average 4.5–5 liters or 1/13 of his body weight. Blood plasma by volume is 55–60%, and formed elements 40–45%. Blood plasma is a yellowish translucent liquid. It consists of water (90–92%), mineral and organic substances (8–10%), 7% proteins. 0.7% fat, 0.1% glucose, the rest of the dense remainder of plasma - hormones, vitamins, amino acids, metabolic products.

Formed elements of blood

Erythrocytes are anucleate red blood cells that have the shape of biconcave discs. This shape increases the cell surface by 1.5 times. The cytoplasm of red blood cells contains the protein hemoglobin - complex organic compound, consisting of the protein globin and the blood pigment heme, which includes iron.

The main function of red blood cells is to transport oxygen and carbon dioxide. Red blood cells develop from nucleated cells in the red bone marrow of cancellous bone. During the process of maturation, they lose their nucleus and enter the blood. 1 mm 3 of blood contains from 4 to 5 million red blood cells.

The lifespan of red blood cells is 120–130 days, then they are destroyed in the liver and spleen, and bile pigment is formed from hemoglobin.

Leukocytes are white blood cells that contain nuclei and do not have a permanent shape. 1 mm 3 of human blood contains 6–8 thousand of them.

Leukocytes are formed in the red bone marrow, spleen, lymph nodes; Their lifespan is 2–4 days. They are also destroyed in the spleen.

The main function of leukocytes is to protect organisms from bacteria, foreign proteins, and foreign bodies. Making amoeboid movements, leukocytes penetrate through the walls of capillaries into the intercellular space. They are sensitive to the chemical composition of substances secreted by microbes or decayed cells of the body, and move towards these substances or decayed cells. Having come into contact with them, leukocytes envelop them with their pseudopods and pull them inside the cell, where they are broken down with the participation of enzymes.

Leukocytes are capable of intracellular digestion. In the process of interaction with foreign bodies, many cells die. At the same time, decay products accumulate around the foreign body, and pus is formed. I. I. Mechnikov called leukocytes that capture various microorganisms and digest them phagocytes, and the phenomenon of absorption and digestion itself was called phagocytosis (absorbing). Phagocytosis is a protective reaction of the body.

Platelets (blood platelets) are colorless, nuclear-free, round-shaped cells that play an important role in blood clotting. There are from 180 to 400 thousand platelets in 1 liter of blood. They are easily destroyed when blood vessels are damaged. Platelets are produced in red bone marrow.

Blood cells, in addition to the above, play a very important role in the human body: during blood transfusion, coagulation, as well as in the production of antibodies and phagocytosis.

Blood transfusion

For some illnesses or blood loss, a person is given a blood transfusion. Large loss of blood disrupts the constancy of the internal environment of the body, blood pressure falls, the amount of hemoglobin decreases. In such cases, blood taken from a healthy person is injected into the body.

Blood transfusions have been used since ancient times, but they often ended fatal. This is explained by the fact that donor red blood cells (that is, red blood cells taken from a person donating blood) can stick together into lumps that close small vessels and impair blood circulation.

The gluing of red blood cells - agglutination - occurs if the donor's red blood cells contain a gluing substance - agglutinogen, and the blood plasma of the recipient (the person to whom blood is transfused) contains the gluing substance agglutinin. Different people have certain agglutinins and agglutinogens in their blood, and in connection with this, the blood of all people is divided into 4 main groups according to their compatibility

The study of blood groups made it possible to develop rules for blood transfusion. Persons giving blood are called donors, and persons receiving it are called recipients. When giving blood transfusions, blood group compatibility is strictly observed.

Any recipient can be injected with blood of group I, since its red blood cells do not contain agglutinogens and do not stick together, therefore persons with blood group I are called universal donors, but they themselves can only be injected with blood of group I.

The blood of people of group II can be transfused to persons with blood groups II and IV, blood of group III - to persons of III and IV. Blood from a group IV donor can be transfused only to persons of this group, but they themselves can be transfused with blood from all four groups. People with blood group IV are called universal recipients.

Blood transfusions treat anemia. It can be caused by the influence of various negative factors, as a result of which the number of red blood cells in the blood decreases, or the content of hemoglobin in them decreases. Anemia also occurs with large blood losses, with insufficient nutrition, dysfunction of the red bone marrow, etc. Anemia is curable: increased nutrition and fresh air help restore the normal level of hemoglobin in the blood.

The blood clotting process is carried out with the participation of the protein prothrombin, which converts the soluble protein fibrinogen into insoluble fibrin, which forms a clot. Under normal conditions, there is no active enzyme thrombin in the blood vessels, so the blood remains liquid and does not clot, but there is an inactive enzyme prothrombin, which is formed with the participation of vitamin K in the liver and bone marrow. The inactive enzyme is activated in the presence of calcium salts and is converted into thrombin by the action of the enzyme thromboplastin, secreted by red blood cells. blood cells- platelets.

When a cut or injection occurs, the platelet membranes are broken, thromboplastin passes into the plasma and the blood clots. The formation of a blood clot in places of vascular damage is a protective reaction of the body, protecting it from blood loss. People whose blood is unable to clot suffer from a serious disease - hemophilia.

Immunity

Immunity is the body's immunity to infectious and non-infectious agents and substances with antigenic properties. In addition to phagocyte cells, the immune reaction of immunity also involves chemical compounds- antibodies (special proteins that neutralize antigens - foreign cells, proteins and poisons). In blood plasma, antibodies glue foreign proteins together or break them down.

Antibodies that neutralize microbial poisons (toxins) are called antitoxins. All antibodies are specific: they are active only against certain microbes or their toxins. If a person’s body has specific antibodies, it becomes immune to these infectious diseases.

The discoveries and ideas of I. I. Mechnikov about phagocytosis and the significant role of leukocytes in this process (in 1863 he gave his famous speech on the healing powers of the body, in which the phagocytic theory of immunity was first outlined) formed the basis of the modern doctrine of immunity (from the Latin . "immunis" - liberated). These discoveries have made it possible to achieve great success in the fight against infectious diseases, which for centuries have been the true scourge of humanity.

The role of protective and therapeutic vaccinations in the prevention of infectious diseases is great - immunization with vaccines and serums that create artificial active or passive immunity in the body.

There are innate (species) and acquired (individual) types of immunity.

Innate immunity is a hereditary trait and ensures immunity to a particular infectious disease from the moment of birth and is inherited from parents. Moreover, immune bodies can penetrate through the placenta from the vessels of the mother’s body into the vessels of the embryo, or newborns receive them with mother’s milk.

Acquired immunity are divided into natural and artificial, and each of them is divided into active and passive.

Natural active immunity produced in humans during the course of an infectious disease. Thus, people who had measles or whooping cough in childhood no longer get sick with them again, since protective substances - antibodies - have formed in their blood.

Natural passive immunity is caused by the transition of protective antibodies from the blood of the mother, in whose body they are formed, through the placenta into the blood of the fetus. Passively and through mother's milk, children receive immunity to measles, scarlet fever, diphtheria, etc. After 1–2 years, when the antibodies received from the mother are destroyed or partially removed from the child's body, his susceptibility to these infections increases sharply.

Artificial active immunity occurs after vaccination of healthy people and animals with killed or weakened pathogenic poisons - toxins. The introduction of these drugs - vaccines - into the body causes a mild form of the disease and activates the body's defenses, causing the formation of appropriate antibodies in it.

To this end, the country is systematically vaccinating children against measles, whooping cough, diphtheria, polio, tuberculosis, tetanus and others, due to which a significant reduction in the number of diseases of these serious diseases has been achieved.

Artificial passive immunity is created by injecting a person with serum (blood plasma without the fibrin protein) containing antibodies and antitoxins against microbes and their poisonous toxins. Serums are obtained mainly from horses, which are immunized with the appropriate toxin. Passively acquired immunity usually lasts no more than a month, but it manifests itself immediately after the administration of the therapeutic serum. A timely administered therapeutic serum containing ready-made antibodies often provides a successful fight against a severe infection (for example, diphtheria), which develops so quickly that the body does not have time to produce a sufficient amount of antibodies and the patient may die.

Immunity through phagocytosis and the production of antibodies protects the body from infectious diseases, frees it from dead, degenerated and foreign cells, and causes rejection of transplanted foreign organs and tissues.

After some infectious diseases, immunity is not developed, for example, against a sore throat, which you can get sick with many times.