The internal environment of an animal's body is called. Components of the internal environment of the human body. Synovial fluid and cerebrospinal fluid

It surrounds all the cells of the body, through which metabolic reactions occur in organs and tissues. Blood (with the exception of hematopoietic organs) does not directly come into contact with cells. From the blood plasma penetrating through the walls of the capillaries, tissue fluid is formed that surrounds all cells. There is a constant exchange of substances between cells and tissue fluid. Part of the tissue fluid enters the thin, blindly closed capillaries of the lymphatic system and from that moment turns into lymph.

Since the internal environment of the body maintains the constancy of physical and chemical properties, which is preserved even with very strong external influences on the body, then all the cells of the body exist in relatively constant conditions. The constancy of the internal environment of the body is called homeostasis. The composition and properties of blood and tissue fluid are maintained at a constant level in the body; bodies; parameters of cardiovascular activity and respiration and more. Homeostasis is maintained by the most complex coordinated work of the nervous and endocrine systems.

Functions and composition of blood: plasma and formed elements

In humans, the circulatory system is closed, and blood circulates through the blood vessels. Blood performs the following functions:

1) respiratory - carries oxygen from the lungs to all organs and tissues and carries carbon dioxide from tissues to the lungs;

2) nutritional - transfers nutrients absorbed in the intestines to all organs and tissues. Thus, they are supplied with amino acids, glucose, breakdown products of fats, mineral salts, vitamins;

3) excretory - delivers metabolic end products (urea, lactic acid salts, creatinine, etc.) from tissues to places of removal (kidneys, sweat glands) or destruction (liver);

4) thermoregulatory - transfers heat from the place of its formation (skeletal muscles, liver) to heat-consuming organs (brain, skin, etc.) with blood plasma water. In heat, the blood vessels of the skin dilate in order to give off excess heat, and the skin turns red. In cold weather, the vessels of the skin contract so that less blood enters the skin and it does not give off heat. At the same time, the skin turns blue;

5) regulatory - blood can retain or give water to tissues, thereby regulating the water content in them. Blood also regulates the acid-base balance in tissues. In addition, it transports hormones and other physiologically active substances from the sites of their formation to the organs that they regulate (target organs);

6) protective - substances contained in the blood protect the body from blood loss due to the destruction of blood vessels, forming a blood clot. By this they also prevent the penetration of pathogenic microorganisms (bacteria, viruses, fungi) into the blood. White blood cells protect the body from toxins and pathogens through phagocytosis and the production of antibodies.

In an adult, blood mass is approximately 6-8% of body weight and equals 5.0-5.5 liters. Some of the blood circulates through the vessels, and about 40% of it is in the so-called depots: vessels of the skin, spleen and liver. If necessary, for example, during high physical exertion or blood loss, blood from the depot is included in the circulation and begins to actively perform its functions. Blood consists of 55-60% plasma and 40-45% formed.

Plasma is the liquid medium of blood, containing 90-92% water and 8-10% various substances. plasmas (about 7%) perform a number of functions. Albumin - retains water in the plasma; globulins are the basis of antibodies; fibrinogen - necessary for blood clotting; various amino acids are transported by blood plasma from the intestines to all tissues; a number of proteins perform enzymatic functions, etc. Inorganic salts (about 1%) contained in plasma include NaCl, salts of potassium, calcium, phosphorus, magnesium, etc. A strictly defined concentration of sodium chloride (0.9%) is necessary to create stable osmotic pressure. If you place red blood cells - erythrocytes - in an environment with a lower NaCl content, they will begin to absorb water until they burst. In this case, a very beautiful and bright “varnish blood” is formed, which is not capable of performing the functions of normal blood. This is why water should not be introduced into the blood during blood loss. If red blood cells are placed in a solution containing more than 0.9% NaCl, then water will be sucked out of the red blood cells and they will shrink. In these cases, the so-called physiological solution is used, which in terms of the concentration of salts, especially NaCl, strictly corresponds to blood plasma. Glucose is contained in blood plasma at a concentration of 0.1%. It is an essential nutrient for all body tissues, but especially the brain. If the glucose content in plasma decreases by approximately half (to 0.04%), then the brain is deprived of its source of energy, the person loses consciousness and can quickly die. Fat in blood plasma is about 0.8%. These are mainly nutrients carried by the blood to places of consumption.

The formed elements of blood include red blood cells, white blood cells and platelets.

Erythrocytes are red blood cells, which are anucleate cells that have the shape of a biconcave disk with a diameter of 7 microns and a thickness of 2 microns. This shape provides the red blood cells with the largest surface area with the smallest volume and allows them to pass through the smallest blood capillaries, quickly delivering oxygen to the tissues. Young human red blood cells have a nucleus, but as they mature, they lose it. Mature red blood cells of most animals have nuclei. One cubic millimeter of blood contains about 5.5 million red blood cells. The main role of red blood cells is respiratory: they deliver oxygen from the lungs to all tissues and remove a significant amount of carbon dioxide from the tissues. Oxygen and CO 2 in red blood cells are bound by the respiratory pigment - hemoglobin. Each red blood cell contains about 270 million hemoglobin molecules. Hemoglobin is a combination of protein - globin - and four non-protein parts - hemes. Each heme contains a molecule of ferrous iron and can add or donate an oxygen molecule. When oxygen joins hemoglobin in the capillaries of the lungs, an unstable compound is formed - oxyhemoglobin. Having reached the capillaries of the tissues, red blood cells containing oxyhemoglobin give oxygen to the tissues, and the so-called reduced hemoglobin is formed, which is now able to attach CO 2.

The resulting also unstable compound HbCO 2 gets into the lungs with the bloodstream, disintegrates, and the resulting CO 2 is removed through the respiratory tract. It should also be taken into account that a significant part of CO 2 is removed from tissues not by hemoglobin of erythrocytes, but in the form of carbonic acid anion (HCO 3 -), formed when CO 2 is dissolved in blood plasma. From this anion, CO 2 is formed in the lungs, which is exhaled out. Unfortunately, hemoglobin is capable of forming a strong compound with carbon monoxide (CO) called carboxyhemoglobin. The presence of only 0.03% CO in the inhaled air leads to the rapid binding of hemoglobin molecules, and red blood cells lose their ability to carry oxygen. In this case, rapid death from suffocation occurs.

Red blood cells are able to circulate through the bloodstream, performing their functions, for about 130 days. Then they are destroyed in the liver and spleen, and the non-protein part of hemoglobin - heme - is repeatedly used in the future in the formation of new red blood cells. New red blood cells are formed in the red bone marrow of the cancellous bone.

Leukocytes are blood cells that have nuclei. The size of leukocytes ranges from 8 to 12 microns. There are 6-8 thousand of them in one cubic millimeter of blood, but this number can fluctuate greatly, increasing, for example, in infectious diseases. This increased level of white blood cells in the blood is called leukocytosis. Some leukocytes are capable of independent amoeboid movements. Leukocytes ensure that the blood performs its protective functions.

There are 5 types of leukocytes: neutrophils, eosinophils, basophils, lymphocytes and monocytes. Most of all there are neutrophils in the blood - up to 70% of all leukocytes. Neutrophils and monocytes, actively moving, recognize foreign proteins and protein molecules, capture them and destroy them. This process was discovered by I.I. Mechnikov and he called it phagocytosis. Neutrophils are not only capable of phagocytosis, but also secrete substances that have a bactericidal effect, promoting tissue regeneration, removing damaged and dead cells from them. Monocytes are called macrophages and their diameter reaches 50 microns. They are involved in the process of inflammation and the formation of an immune response and not only destroy pathogenic bacteria and protozoa, but are also capable of destroying cancer cells, old and damaged cells in our body.

Lymphocytes play a critical role in the formation and maintenance of the immune response. They are able to recognize foreign bodies (antigens) on their surface and produce specific protein molecules (antibodies) that bind these foreign agents. They are also able to remember the structure of antigens, so that when these agents are reintroduced into the body, an immune response occurs very quickly, more antibodies are formed and the disease may not develop. The first to react to antigens entering the blood are the so-called B lymphocytes, which immediately begin to produce specific antibodies. Some B lymphocytes turn into memory B cells, which exist in the blood for a very long time and are capable of reproduction. They remember the structure of the antigen and store this information for years. Another type of lymphocyte, T lymphocytes, regulates the functioning of all other cells responsible for immunity. Among them there are also immune memory cells. White blood cells are produced in the red bone marrow and lymph nodes and destroyed in the spleen.

Platelets are very small, non-nuclear cells. Their number reaches 200-300 thousand in one cubic millimeter of blood. They are formed in the red bone marrow, circulate in the bloodstream for 5-11 days, and then are destroyed in the liver and spleen. When a vessel is damaged, platelets release substances necessary for blood clotting, promoting the formation of a blood clot and stopping bleeding.

Blood groups

The problem of blood transfusion arose a long time ago. Even the ancient Greeks tried to save bleeding wounded soldiers by giving them warm animal blood to drink. But there could not be much benefit from this. At the beginning of the 19th century, the first attempts were made to transfuse blood directly from one person to another, but a very large number of complications were observed: after blood transfusion, red blood cells stuck together and were destroyed, which led to the death of the person. At the beginning of the 20th century, K. Landsteiner and J. Jansky created the doctrine of blood groups, which makes it possible to accurately and safely replace blood loss in one person (recipient) with the blood of another (donor).

It turned out that the membranes of red blood cells contain special substances with antigenic properties - agglutinogens. Specific antibodies dissolved in the plasma that belong to the globulin fraction - agglutinins - can react with them. During the antigen-antibody reaction, bridges are formed between several red blood cells and they stick together.

The most common system for dividing blood into 4 groups. If agglutinin α meets agglutinogen A after transfusion, red blood cells will stick together. The same thing happens when B and β meet. Currently, it has been shown that only the blood of his group can be transfused into a donor, although more recently it was believed that with small volumes of transfusion, the donor’s plasma agglutinins become highly diluted and lose their ability to glue the recipient’s red blood cells together. People with blood group I (0) can receive any blood transfusion, since their red blood cells do not stick together. Therefore, such people are called universal donors. People with blood group IV (AB) can be transfused with small amounts of any blood - these are universal recipients. However, it is better not to do this.

More than 40% of Europeans have blood group II (A), 40% - I (0), 10% - III (B) and 6% - IV (AB). But 90% of American Indians have I (0) blood type.

blood clotting

Blood clotting is the most important protective reaction that protects the body from blood loss. Bleeding occurs most often with the mechanical destruction of blood vessels. For an adult male, blood loss of approximately 1.5-2.0 liters is considered conditionally fatal, while women can tolerate the loss of even 2.5 liters of blood. In order to avoid blood loss, the blood at the site of damage to the vessel must quickly clot, forming a blood clot. A thrombus is formed by the polymerization of an insoluble plasma protein, fibrin, which, in turn, is formed from a soluble plasma protein, fibrinogen. The process of blood coagulation is very complex, includes many stages, is catalyzed by many. It is controlled by both nervous and humoral pathways. In a simplified way, the process of blood clotting can be depicted as follows.

Diseases are known in which the body lacks one or another factor necessary for blood clotting. An example of such a disease is hemophilia. Clotting is also slowed down when the diet lacks vitamin K, which is necessary for the synthesis of certain protein clotting factors by the liver. Since the formation of blood clots in the lumens of intact vessels, leading to strokes and heart attacks, is deadly, the body has a special anticoagulant system that protects the body from vascular thrombosis.

Lymph

Excess tissue fluid enters blindly closed lymphatic capillaries and turns into lymph. In its composition, lymph is similar to blood plasma, but it contains much less proteins. The functions of lymph, like blood, are aimed at maintaining homeostasis. With the help of lymph, proteins are returned from the intercellular fluid to the blood. Lymph contains many lymphocytes and macrophages, and plays a large role in immune responses. In addition, the products of fat digestion in the villi of the small intestine are absorbed into the lymph.

The walls of the lymphatic vessels are very thin, they have folds that form valves, thanks to which the lymph moves through the vessel in only one direction. At the confluence of several lymphatic vessels there are lymph nodes that perform a protective function: they retain and destroy pathogenic bacteria, etc. The largest lymph nodes are located in the neck, groin, and axillary areas.

Immunity

Immunity is the body's ability to protect itself from infectious agents (bacteria, viruses, etc.) and foreign substances (toxins, etc.). If a foreign agent has penetrated the protective barriers of the skin or mucous membranes and entered the blood or lymph, it must be destroyed by binding to antibodies and (or) absorption by phagocytes (macrophages, neutrophils).

Immunity can be divided into several types: 1. Natural - congenital and acquired 2. Artificial - active and passive.

Natural innate immunity is transmitted to the body with genetic material from ancestors. Natural acquired immunity occurs when the body itself has developed antibodies to some antigen, for example, having had measles, smallpox, etc., and has retained the memory of the structure of this antigen. Artificial active immunity occurs when a person is injected with weakened bacteria or other pathogens (vaccine) and this leads to the production of antibodies. Artificial passive immunity appears when a person is injected with serum - ready-made antibodies from a recovered animal or another person. This immunity is the most unstable and lasts only a few weeks.

/ 14.11.2017

Internal environment of the human body

B) Superior and inferior vena cava D) Pulmonary arteries

7. Blood enters the aorta from:

A) Left ventricle of the heart B) Left atrium

B) Right ventricle of the heart D) Right atrium

8. Open leaflet heart valves occur at the moment:

A) Ventricular contractions B) Atrial contractions

B) Relaxation of the heart D) Transfer of blood from the left ventricle to the aorta

9. The maximum blood pressure is considered to be:

B) Right ventricle D) Aorta

10. The ability of the heart to self-regulate is evidenced by:

A) Heart rate measured immediately after exercise

B) Pulse measured before exercise

B) The rate at which heart rate returns to normal after exercise

D) Comparison of the physical characteristics of two people

Since the internal environment of the body maintains constancy of physical and chemical properties, which persist even with very strong external influences on the body, then all the cells of the body exist in relatively constant conditions. The constancy of the internal environment of the body is called homeostasis. The composition and properties of blood and tissue fluid are maintained at a constant level in the body; bodies; parameters of cardiovascular activity and respiration and more. Homeostasis is maintained by the most complex coordinated work of the nervous and endocrine systems.

Functions and composition of blood: plasma and formed elements

In humans, the circulatory system is closed, and blood circulates through the blood vessels. Blood performs the following functions:

1) respiratory - carries oxygen from the lungs to all organs and tissues and carries carbon dioxide from tissues to the lungs;

2) nutritional - transfers nutrients absorbed in the intestines to all organs and tissues. In this way, the tissues are supplied with water, amino acids, glucose, fat breakdown products, mineral salts, vitamins;

3) excretory - delivers metabolic end products (urea, lactic acid salts, creatinine, etc.) from tissues to places of removal (kidneys, sweat glands) or destruction (liver);

6) protective - substances contained in the blood protect the body from blood loss due to the destruction of blood vessels, forming a blood clot. By this they also prevent the penetration of pathogenic microorganisms (bacteria, viruses, protozoa, fungi) into the blood. White blood cells protect the body from toxins and pathogens through phagocytosis and the production of antibodies.

In an adult, blood mass is approximately 6-8% of body weight and equals 5.0-5.5 liters. Some of the blood circulates through the vessels, and about 40% of it is in the so-called depots: vessels of the skin, spleen and liver. If necessary, for example during high physical exertion or blood loss, blood from the depot is included in the circulation and begins to actively perform its functions. Blood consists of 55-60% plasma and 40-45% formed elements.

Plasma is the liquid medium of blood, containing 90-92% water and 8-10% various substances. Plasma proteins (about 7%) perform a number of functions. Albumin - retains water in the plasma; globulins are the basis of antibodies; fibrinogen - necessary for blood clotting; various amino acids are transported by blood plasma from the intestines to all tissues; a number of proteins perform enzymatic functions, etc. Inorganic salts (about 1%) contained in plasma include NaCl, salts of potassium, calcium, phosphorus, magnesium, etc. A strictly defined concentration of sodium chloride (0.9%) is necessary to create stable osmotic pressure. If you place red blood cells - erythrocytes - in an environment with a lower NaCl content, they will begin to absorb water until they burst. In this case, a very beautiful and bright “varnish blood” is formed, which is not capable of performing the functions of normal blood. This is why water should not be introduced into the blood during blood loss. If red blood cells are placed in a solution containing more than 0.9% NaCl, it will be sucked out of the red blood cells and they will shrink. In these cases, the so-called physiological solution is used, which in terms of the concentration of salts, especially NaCl, strictly corresponds to blood plasma. Glucose is contained in blood plasma at a concentration of 0.1%. It is an essential nutrient for all body tissues, but especially the brain. If the glucose content in plasma decreases by approximately half (to 0.04%), then the brain is deprived of its source of energy, the person loses consciousness and can quickly die. Fat in blood plasma is about 0.8%. These are mainly nutrients carried by the blood to places of consumption.

The formed elements of blood include red blood cells, white blood cells and platelets.

Blood groups

More than 40% of Europeans have blood group II (A), 40% - I (0), 10% - III (B) and 6% - IV (AB). But 90% of American Indians have I (0) blood type.

blood clotting

Blood clotting is the most important protective reaction that protects the body from blood loss. Bleeding occurs most often due to mechanical destruction of blood vessels. For an adult male, blood loss of approximately 1.5-2.0 liters is considered conditionally fatal, while women can tolerate the loss of even 2.5 liters of blood. In order to avoid blood loss, the blood at the site of damage to the vessel must quickly clot, forming a blood clot. A thrombus is formed by the polymerization of an insoluble plasma protein, fibrin, which, in turn, is formed from a soluble plasma protein, fibrinogen. The process of blood clotting is very complex, includes many stages, and is catalyzed by many enzymes. It is controlled by both nervous and humoral pathways. In a simplified way, the process of blood clotting can be depicted as follows.

Lymph

Immunity

Immunity can be divided into several types: 1. Natural - congenital and acquired 2. Artificial - active and passive.

Blood, tissue fluid, lymph and their functions. Immunity

Blood, lymph and tissue fluid form the internal environment of the body, which surrounds all its cells. The chemical composition and physicochemical properties of the internal environment are relatively constant, therefore the cells of the body exist in relatively stable conditions and are little exposed to environmental factors. Ensuring the constancy of the internal environment is achieved by the continuous and coordinated work of many organs (heart, digestive, respiratory, excretory systems), which supply the body with substances necessary for life and remove decay products from it. Regulatory function to maintain the constancy of the parameters of the internal environment of the body - homeostasis-for- carried out by the nervous and endocrine systems.

There is a close relationship between the three components of the body’s internal environment. So, colorless and translucent tissue fluid is formed from the liquid part of the blood - plasma, penetrating through the walls of the capillaries into the intercellular space, and from waste products coming from the cells (Fig. 4.13). In an adult, its volume reaches 20 liters per day. Blood supplies the tissue fluid with the dissolved nutrients, oxygen, hormones necessary for the cells and absorbs the waste products of the cells - carbon dioxide, urea, etc.

A smaller part of the tissue fluid, without having time to return to the bloodstream, enters the blindly closed capillaries of the lymphatic vessels, forming lymph. In appearance it is a translucent yellowish liquid. The composition of lymph is close to the composition of blood plasma. However, it contains 3-4 times less protein than plasma, but more than tissue fluid. Lymph contains a small number of leukocytes. Small lymphatic vessels merge to form larger ones. They have semilunar valves that ensure lymph flow in one direction - to the thoracic and right lymphatic ducts, which flow into

into the superior vena cava. In the numerous lymph nodes through which lymph flows, it is neutralized due to the activity of leukocytes and enters the blood purified. The movement of lymph is slow, about 0.2-0.3 mm per minute. It occurs mainly due to contractions of skeletal muscles, the suction action of the chest during inhalation and, to a lesser extent, due to contractions of the muscles of the own walls of the lymphatic vessels. About 2 liters of lymph return to the blood per day. In pathological phenomena that disrupt the outflow of lymph, tissue swelling is observed.

Blood is the third component of the internal environment of the body. This is a bright red liquid that continuously circulates in a closed system of human blood vessels and makes up about 6-8% of the total body weight. The liquid part of the blood - plasma - makes up about 55%, the rest is formed elements - blood cells.

IN plasma about 90-91% water, 7-8% proteins, 0.5% lipids, 0.12% monosaccharides and 0.9% mineral salts. It is plasma that transports various substances and blood cells.

Plasma proteins fibrinogen And prothrombin take part in blood clotting, globulins play an important role in the body's immune reactions, albumins They give viscosity to the blood and bind calcium present in the blood.

Among blood cells most red blood cells- red blood cells. These are small biconcave disks without a nucleus. Their diameter is approximately equal to the diameter of the narrowest capillaries. Red blood cells contain hemoglobin, which easily binds to oxygen in areas where its concentration is high (lungs), and just as easily releases it in areas with low oxygen concentration (tissues).

Leukocytes- white nuclear blood cells are slightly larger in size than red blood cells, but contain much less of them in the blood. They play an important role in protecting the body from disease. Due to their ability of amoeboid movement, they can pass through small pores in the walls of capillaries in places where pathogenic bacteria are present and absorb them by phagocytosis. Other

types of white blood cells are capable of producing protective proteins - antibodies- in response to a foreign protein entering the body.

Platelets (blood platelets)- the smallest of blood cells. Platelets contain substances that play an important role in blood clotting.

One of the most important protective functions of blood - protective - is carried out with the participation of three mechanisms:

A) blood clotting, thanks to which blood loss is prevented due to injuries to blood vessels;

b) phagocytosis, carried out by leukocytes capable of amoeboid movement and phagocytosis;

V) immune protection, carried out by antibodies.

blood clotting- a complex enzymatic process involving the transfer of soluble protein in blood plasma fibrinogen into insoluble protein fibrin, forming the basis of a blood clot - blood clot The blood clotting process is triggered by the release of an active enzyme from platelets destroyed during injury. thromboplastin, which, in the presence of calcium ions and vitamin K, through a series of intermediate substances, leads to the formation of fibrin filamentous protein molecules. Red blood cells are retained in the network formed by fibrin fibers, resulting in the formation of a blood clot. Drying and shrinking, it turns into a crust that prevents blood loss.

Phagocytosis carried out by certain types of leukocytes that are capable of moving with the help of pseudopods to places where cells and tissues of the body are damaged, where microorganisms are found. Having approached and then pressed against the microbe, the leukocyte absorbs it into the cell, where it is digested under the influence of lysosome enzymes.

Immune protection carried out thanks to the ability of protective proteins - antibodies- recognize foreign material that has entered the body and induce the most important immunophysiological mechanisms aimed at its neutralization. Foreign material can be protein molecules on the surface of microbial cells or foreign cells, tissues, surgically transplanted organs, or changed cells of one's own body (for example, cancerous ones).

Based on their origin, they distinguish between innate and acquired immunity.

Congenital (hereditary, or species) immunity is predetermined genetically and is determined by biological, hereditary characteristics. This immunity is inherited and is characterized by the immunity of one species of animals and humans to pathogenic agents that cause diseases in other species.

Acquired immunity can be natural or artificial. Natural immunity is immunity to a particular disease obtained by the child’s body as a result of the penetration of mother’s antibodies into the fetus’ body

through the placenta (placental immunity), or acquired as a result of a previous disease (post-infectious immunity).

Artificial immunity can be active and passive. Active artificial immunity is developed in the body after the introduction of a vaccine - a drug containing weakened or killed pathogens of a particular disease. Such immunity is less durable than post-infectious immunity and, as a rule, to maintain it, repeated vaccination is necessary after several years. In medical practice, passive immunization is widely used, when a sick person is injected with therapeutic serums that already contain ready-made antibodies against this pathogen. Such immunity will persist until the antibodies die (1-2 months).

Blood, woven fluid and lymph - internal Wednesday body For What is more characteristic is the relative constancy of the chemical composition Ava and physical and chemical properties, which is achieved by the continuous and coordinated work of many organs. Metabolism between blood and cells occurs through tissue liquid.

Protective: function blood is carried out thanks to coagulation, phagocytosis And immune health look for. There are congenital and acquired y immunity. When acquired immunity can be natural or artificial.

I. What is the relationship between the elements of the internal environment of the human body? 2. What is the role of blood plasma? 3. What is the relationship between the structure of erythro-

cytes with the functions they perform? 4. How the protective function is carried out

5. Give a rationale for the concepts: hereditary, natural and artificial, active and passive immunity.

The body of any animal is extremely complex. This is necessary to maintain homeostasis, that is, constancy. For some, the condition is conditionally constant, while for others, more developed, actual constancy is observed. This means that no matter how the environmental conditions change, the body maintains a stable state of the internal environment. Despite the fact that organisms have not yet fully adapted to living conditions on the planet, the internal environment of the organism plays a crucial role in their life.

The concept of internal environment

The internal environment is a complex of structurally separate areas of the body, under no circumstances, other than mechanical damage, not in contact with the outside world. In the human body, the internal environment is represented by blood, interstitial and synovial fluid, cerebrospinal fluid and lymph. These 5 types of fluids together constitute the internal environment of the body. They are called this for three reasons:

firstly, they do not come into contact with the external environment;
secondly, these fluids maintain homeostasis;
thirdly, the environment is an intermediary between cells and the external parts of the body, protecting against external adverse factors.

The importance of the internal environment for the body

The internal environment of the body consists of 5 types of fluids, the main task of which is to maintain a constant level of nutrient concentrations near the cells, maintaining the same acidity and temperature. Due to these factors, it is possible to ensure the functioning of cells, the most important of which in the body is nothing, since they make up tissues and organs. Therefore, the internal environment of the body is the widest transport system and the area where extracellular reactions occur.

It transports nutrients and carries metabolic products to the site of destruction or excretion. Also, the internal environment of the body transports hormones and mediators, allowing some cells to regulate the work of others. This is the basis of humoral mechanisms that ensure the occurrence of biochemical processes, the overall result of which is homeostasis.

It turns out that the entire internal environment of the body (IEC) is the place where all nutrients and biologically active substances should go. This is an area of the body that should not accumulate metabolic products. And in the basic understanding, VSO is the so-called road along which “couriers” (tissue and synovial fluid, blood, lymph and cerebrospinal fluid) deliver “food” and “building material” and remove harmful metabolic products.

Early internal environment of organisms

All representatives of the animal kingdom evolved from single-celled organisms. Their only component of the internal environment of the body was the cytoplasm. From the external environment it was limited by the cell wall and the cytoplasmic membrane. Then the further development of animals proceeded according to the principle of multicellularity. In coelenterate organisms there was a cavity separating the cells and the external environment. It was filled with hydrolymph, in which nutrients and products of cellular metabolism were transported. This type of internal environment was present in flatworms and coelenterates.

Development of the internal environment

In animals of the classes of roundworms, arthropods, mollusks (with the exception of cephalopods) and insects, the internal environment of the body consists of other structures. These are vessels and areas of an open channel through which hemolymph flows. Its main feature is the acquisition of the ability to transport oxygen through hemoglobin or hemocyanin. In general, such an internal environment is far from perfect, which is why it has developed further.

Perfect indoor environment

A perfect internal environment is a closed system, which excludes the possibility of fluid circulation through isolated areas of the body. This is how the bodies of representatives of the classes of vertebrates, annelids and cephalopods are arranged. Moreover, it is most perfect in mammals and birds, which, to support homeostasis, also have a 4-chambered heart, which provides them with warm-bloodedness.

The components of the internal environment of the body are as follows: blood, lymph, joint and tissue fluid, cerebrospinal fluid. It has its own walls: the endothelium of arteries, veins and capillaries, lymphatic vessels, the joint capsule and ependymocytes. On the other side of the internal environment lie the cytoplasmic membranes of the cells with which it is in contact, also included in the BSO.

Blood

The internal environment of the body is partly formed by blood. This is a liquid that contains formed elements, proteins and some elementary substances. A lot of enzymatic processes take place here. But the main function of blood is transport, especially oxygen to cells and carbon dioxide from them. Therefore, the largest proportion of formed elements in the blood are erythrocytes, platelets, and leukocytes. The former are involved in the transport of oxygen and carbon dioxide, although they can also play an important role in immune reactions due to reactive oxygen species.

Leukocytes in the blood are completely occupied only with immune reactions. They participate in the immune response, regulate its strength and completeness, and also store information about antigens with which they have previously been in contact. Since the internal environment of the body is partly formed by blood, which plays the role of a barrier between areas of the body in contact with the external environment and cells, the immune function of blood is second in importance after transport. At the same time, it requires the use of both formed elements and plasma proteins.

The third important function of blood is hemostasis. This concept combines several processes that are aimed at maintaining the liquid consistency of the blood and covering defects in the vascular wall when they appear. The hemostasis system ensures that the blood flowing through the vessels remains liquid until the damaged vessel needs to be closed. Moreover, the internal environment of the human body will not be affected, although this requires energy expenditure and the involvement of platelets, erythrocytes and plasma factors of the coagulation and anticoagulation system.

Blood proteins

The second part of the blood is liquid. It consists of water in which proteins, glucose, carbohydrates, lipoproteins, amino acids, vitamins with their carriers and other substances are evenly distributed. Among the proteins, high molecular weight and low molecular weight are distinguished. The first are represented by albumins and globulins. These proteins are responsible for the functioning of the immune system, maintaining plasma oncotic pressure, and the functioning of the coagulation and anticoagulation systems.

Carbohydrates dissolved in the blood act as transported energy-intensive substances. This is a nutrient substrate that must enter the intercellular space, from where it will be captured by the cell and processed (oxidized) in its mitochondria. The cell will receive the energy necessary for the operation of systems responsible for the synthesis of proteins and the performance of functions for the benefit of the entire organism. At the same time, amino acids, also dissolved in the blood plasma, also penetrate the cell and serve as a substrate for protein synthesis. The latter is a tool for the cell to realize its hereditary information.

The role of blood plasma lipoproteins

Another important source of energy, in addition to glucose, is triglyceride. This is fat that must be broken down and become an energy carrier for muscle tissue. It is she who, for the most part, is able to process fats. By the way, they contain much more energy than glucose, and therefore are able to provide muscle contraction for a much longer period than glucose.

Fats are transported into cells using membrane receptors. Fat molecules absorbed in the intestine are first combined into chylomicrons and then enter the intestinal veins. From there, chylomicrons pass to the liver and enter the lungs, where they form low-density lipoproteins. The latter are transport forms in which fats are delivered through the blood into the intercellular fluid to muscle sarcomeres or smooth muscle cells.

Also, blood and intercellular fluid, together with lymph, which make up the internal environment of the human body, transport metabolic products of fats, carbohydrates, and proteins. They are partially contained in the blood, which carries them to the site of filtration (kidney) or disposal (liver). It is obvious that these biological fluids, which are the media and compartments of the body, play a vital role in the life of the body. But much more important is the presence of a solvent, that is, water. Only thanks to it can substances be transported and cells exist.

Intercellular fluid

It is believed that the composition of the internal environment of the body is approximately constant. Any fluctuations in the concentration of nutrients or metabolic products, changes in temperature or acidity lead to dysfunction. Sometimes they can lead to death. By the way, it is acidity disorders and acidification of the internal environment of the body that is the fundamental and most difficult to correct dysfunction.

This is observed in cases of polyarganic insufficiency, when acute liver and kidney failure develops. These organs are designed to utilize acidic metabolic products, and when this does not happen, there is an immediate threat to the patient’s life. Therefore, in reality, all components of the internal environment of the body are very important. But much more important is the performance of organs, which also depend on the VSO.

It is the intercellular fluid that reacts first to changes in the concentrations of nutrients or metabolic products. Only then does this information enter the blood through mediators secreted by the cells. The latter supposedly transmit a signal to cells in other areas of the body, urging them to take action to correct the problems that have arisen. So far, this system is the most effective of all those presented in the biosphere.

Lymph

Lymph is also the internal environment of the body, the functions of which are limited to the distribution of leukocytes throughout the body and the removal of excess fluid from the interstitial space. Lymph is a fluid containing low and high molecular weight proteins, as well as some nutrients.

It is drained from the interstitial space through tiny vessels that collect and form lymph nodes. Lymphocytes actively multiply in them, playing an important role in the implementation of immune reactions. From the lymphatic vessels it collects into the thoracic duct and flows into the left venous angle. Here the fluid returns to the bloodstream.

Synovial fluid and cerebrospinal fluid

Synovial fluid is a variant of the intercellular fluid fraction. Since cells cannot penetrate into the articular capsule, the only way to nourish the articular cartilage is the synovial cartilage. All articular cavities are the internal environment of the body, because they are in no way connected to the structures in contact with the external environment.

Also included in the VSO are all the ventricles of the brain, along with the cerebrospinal fluid and the subarachnoid space. CSF is already a variant of lymph, since the nervous system does not have its own lymphatic system. Through cerebrospinal fluid, the brain is cleared of metabolic products, but is not nourished by it. The brain is nourished by blood, products dissolved in it and bound oxygen.

Through the blood-brain barrier, they penetrate neurons and glial cells, delivering the necessary substances to them. Metabolic products are removed through the cerebrospinal fluid and the venous system. Moreover, probably the most important function of cerebrospinal fluid is to protect the brain and nervous system from temperature fluctuations and mechanical damage. Since the liquid actively dampens mechanical impacts and shocks, this property is really necessary for the body.

Conclusion

The external and internal environments of the body, despite their structural isolation from each other, are inextricably linked by a functional connection. Namely, the external environment is responsible for the flow of substances into the internal environment, from where it removes metabolic products. And the internal environment transfers nutrients to the cells, removing harmful products from them. In this way, homeostasis, the main characteristic of life, is maintained. This also means that it is virtually impossible to separate the external environment of otragism from the internal one.

The internal environment of the body is blood, lymph and fluid that fills the spaces between cells and tissues. The blood and lymphatic vessels that penetrate all human organs have tiny pores in their walls through which even some blood cells can penetrate. Water, which forms the basis of all fluids in the body, together with organic and inorganic substances dissolved in it, easily passes through the walls of blood vessels. As a result, the chemical composition of blood plasma (that is, the liquid part of the blood that does not contain cells), lymph and tissue liquids is largely the same. With age, there are no significant changes in the chemical composition of these fluids. At the same time, differences in the composition of these fluids may be associated with the activity of the organs in which these fluids are located.

Blood

Blood composition. Blood is a red, opaque liquid consisting of two fractions - liquid, or plasma, and solid, or cells - blood cells. It is quite easy to separate blood into these two fractions using a centrifuge: the cells are heavier than plasma and in a centrifuge tube they collect at the bottom in the form of a red clot, and a layer of transparent and almost colorless liquid remains above it. This is plasma.

Plasma. The adult human body contains about 3 liters of plasma. In a healthy adult, plasma makes up more than half (55%) of the blood volume, in children it is slightly less.

More than 90% of plasma composition - water, the rest is inorganic salts dissolved in it, as well as organic matter: carbohydrates, carboxylic, fatty acids and amino acids, glycerin, soluble proteins and polypeptides, urea, etc. Together they determine blood osmotic pressure, which in the body is maintained at a constant level so as not to cause harm to the cells of the blood itself, as well as to all other cells of the body: increased osmotic pressure leads to shrinkage of cells, and with reduced osmotic pressure they swell. In both cases, cells may die. Therefore, for the introduction of various drugs into the body and for transfusion of blood-replacing fluids in case of large blood loss, special solutions are used that have exactly the same osmotic pressure as blood (isotonic). Such solutions are called physiological. The simplest physiological solution in composition is a 0.1% solution of sodium chloride NaCl (1 g of salt per liter of water). Plasma is involved in the transport function of blood (transports substances dissolved in it), as well as the protective function, since some proteins dissolved in plasma have an antimicrobial effect.

Blood cells. There are three main types of cells in the blood: red blood cells, or red blood cells, white blood cells, or leukocytes; blood platelets, or platelets. Cells of each of these types perform specific physiological functions, and together they determine the physiological properties of blood. All blood cells are short-lived (the average lifespan is 2 - 3 weeks), therefore, throughout life, special hematopoietic organs are engaged in the production of more and more new blood cells. Hematopoiesis occurs in the liver, spleen and bone marrow, as well as in the lymph glands.

Red blood cells(Fig. 11) are anucleate disc-shaped cells, devoid of mitochondria and some other organelles and adapted for one main function - to be oxygen carriers. The red color of red blood cells is determined by the fact that they carry the protein hemoglobin (Fig. 12), in which the functional center, the so-called heme, contains an iron atom in the form of a divalent ion. Heme is capable of chemically combining with an oxygen molecule (the resulting substance is called oxyhemoglobin) if the partial pressure of oxygen is high. This bond is fragile and is easily destroyed if the partial pressure of oxygen drops. It is on this property that the ability of red blood cells to carry oxygen is based. Once in the lungs, the blood in the pulmonary vesicles finds itself in conditions of increased oxygen tension, and hemoglobin actively captures atoms of this gas, which is poorly soluble in water. But as soon as blood enters working tissues that actively use oxygen, oxyhemoglobin easily gives it away, obeying the “oxygen demand” of the tissues. During active functioning, tissues produce carbon dioxide and other acidic products that exit through the cell walls into the blood. This further stimulates oxyhemoglobin to release oxygen, since the chemical bond between hemoglobin and oxygen is very sensitive to the acidity of the environment. In return, heme attaches a CO 2 molecule to itself, carrying it to the lungs, where this chemical bond is also destroyed, CO 2 is carried out with the current of exhaled air, and hemoglobin is released and is again ready to attach oxygen.

Rice. 10. Red blood cells: a - normal red blood cells in the shape of a biconcave disc; b - wrinkled red blood cells in hypertonic saline solution

If carbon monoxide CO is present in the inhaled air, it enters into a chemical interaction with hemoglobin in the blood, resulting in the formation of a strong substance, methoxyhemoglobin, which does not disintegrate in the lungs. Thus, hemoglobin in the blood is removed from the process of oxygen transfer, tissues do not receive the required amount of oxygen, and the person feels suffocated. This is the mechanism of human poisoning in a fire. A similar effect is exerted by some other instant poisons, which also disable hemoglobin molecules, for example, hydrocyanic acid and its salts (cyanides).

Rice. 11. Spatial model of the hemoglobin molecule

Every 100 ml of blood contains about 12 g of hemoglobin. Each hemoglobin molecule is capable of “carrying” 4 oxygen atoms. The blood of an adult contains a huge number of red blood cells - up to 5 million in one milliliter. Newborns have even more of them - up to 7 million, which means more hemoglobin. If a person lives for a long time in conditions of lack of oxygen (for example, high in the mountains), then the number of red blood cells in his blood increases even more. As the body ages, the number of red blood cells changes in waves, but in general, children have slightly more of them than adults. A decrease in the number of red blood cells and hemoglobin in the blood below normal indicates a serious illness - anemia (anemia). One of the causes of anemia may be a lack of iron in food. Foods such as beef liver, apples and some others are rich in iron. In cases of prolonged anemia, it is necessary to take medications containing iron salts.

Along with determining the level of hemoglobin in the blood, the most common clinical blood tests include measuring the erythrocyte sedimentation rate (ESR), or erythrocyte sedimentation reaction (ERS), - these are two equal names for the same test. If you prevent blood clotting and leave it in a test tube or capillary for several hours, then without mechanical shaking, heavy red blood cells will begin to precipitate. The speed of this process in adults ranges from 1 to 15 mm/h. If this indicator is significantly higher than normal, this indicates the presence of a disease, most often inflammatory. In newborns, ESR is 1-2 mm/h. By the age of 3, ESR begins to fluctuate - from 2 to 17 mm/h. In the period from 7 to 12 years, ESR usually does not exceed 12 mm/h.

Leukocytes- white blood cells. They do not contain hemoglobin, so they are not red in color. The main function of leukocytes is to protect the body from pathogenic microorganisms and toxic substances that have penetrated inside it. Leukocytes are able to move using pseudopodia, like amoebas. This way they can leave the blood capillaries and lymphatic vessels, in which there are also a lot of them, and move towards the accumulation of pathogenic microbes. There they devour microbes, carrying out the so-called phagocytosis.

There are many types of white blood cells, but the most typical are lymphocytes, monocytes and neutrophils. Neutrophils, which, like erythrocytes, are formed in the red bone marrow, are most active in the processes of phagocytosis. Each neutrophil can absorb 20-30 microbes. If a large foreign body (for example, a splinter) invades the body, then many neutrophils stick around it, forming a kind of barrier. Monocytes - cells formed in the spleen and liver, also participate in the processes of phagocytosis. Lymphocytes, which are formed mainly in the lymph nodes, are not capable of phagocytosis, but are actively involved in other immune reactions.

1 ml of blood normally contains from 4 to 9 million leukocytes. The ratio between the number of lymphocytes, monocytes and neutrophils is called the blood formula. If a person gets sick, the total number of leukocytes increases sharply, and the blood formula also changes. By its change, doctors can determine what type of microbe the body is fighting.

In a newborn child, the number of white blood cells is significantly (2-5 times) higher than in an adult, but after a few days it decreases to a level of 10-12 million per 1 ml. Starting from the 2nd year of life, this value continues to decrease and reaches typical adult values after puberty. In children, the processes of formation of new blood cells are very active, therefore among the blood leukocytes in children there are significantly more young cells than in adults. Young cells differ in their structure and functional activity from mature ones. After 15-16 years, the blood formula acquires the parameters characteristic of adults.

Platelets- the smallest formed elements of blood, the number of which reaches 200-400 million in 1 ml. Muscular work and other types of stress can increase the number of platelets in the blood several times (this, in particular, is the danger of stress for older people: after all, blood clotting depends on platelets, including the formation of blood clots and blockage of small vessels in the brain and heart muscles). The place of platelet formation is the red bone marrow and spleen. Their main function is to ensure blood clotting. Without this function, the body becomes vulnerable at the slightest injury, and the danger lies not only in the fact that a significant amount of blood is lost, but also in the fact that any open wound is a gateway to infection.

If a person is injured, even shallowly, the capillaries are damaged, and platelets along with blood end up on the surface. Here they are affected by two important factors - low temperature (much lower than 37 ° C inside the body) and an abundance of oxygen. Both of these factors lead to the destruction of platelets, and from them substances are released into the plasma that are necessary for the formation of a blood clot - a thrombus. In order for a blood clot to form, the blood must be stopped by squeezing a large vessel if blood is pouring heavily from it, since even the process of thrombus formation that has begun will not go to completion if new and new portions of blood with a high temperature are constantly entering the wound and not yet destroyed platelets.

To prevent blood from clotting inside the vessels, it contains special anti-clotting substances - heparin, etc. As long as the vessels are not damaged, there is a balance between substances that stimulate and inhibit coagulation. Damage to blood vessels leads to disruption of this balance. In old age and with increasing disease, this balance in a person is also disturbed, which increases the risk of blood clotting in small vessels and the formation of a life-threatening blood clot.

Age-related changes in platelet function and blood coagulation were studied in detail by A. A. Markosyan, one of the founders of age-related physiology in Russia. It was found that in children, coagulation occurs more slowly than in adults, and the resulting clot has a looser structure. These studies led to the formation of the concept of biological reliability and its increase in ontogenesis.

Immunity to diseases due to the presence of special protective substances in the blood and tissues is called immunity.

The immune system

B) Superior and inferior vena cava D) Pulmonary arteries

7. Blood enters the aorta from:

A) Left ventricle of the heart B) Left atrium

B) Right ventricle of the heart D) Right atrium

8. Open leaflet heart valves occur at the moment:

A) Ventricular contractions B) Atrial contractions

B) Relaxation of the heart D) Transfer of blood from the left ventricle to the aorta

9. The maximum blood pressure is considered to be:

B) Right ventricle D) Aorta

10. The ability of the heart to self-regulate is evidenced by:

A) Heart rate measured immediately after exercise

B) Pulse measured before exercise

B) The rate at which heart rate returns to normal after exercise

D) Comparison of the physical characteristics of two people

Blood, lymph, and tissue fluid form the internal environment of the body. From blood plasma penetrating through the walls of capillaries, tissue fluid is formed, which washes the cells. There is a constant exchange of substances between tissue fluid and cells. The circulatory and lymphatic systems provide humoral communication between organs, combining metabolic processes into a common system. The relative constancy of the physicochemical properties of the internal environment contributes to the existence of body cells in fairly constant conditions and reduces the influence of the external environment on them. The constancy of the internal environment - homeostasis - of the body is supported by the work of many organ systems, which ensure self-regulation of vital processes, interaction with the environment, the supply of substances necessary for the body and remove decay products from it.

1. Composition and functions of blood

Blood performs the following functions: transport, heat distribution, regulatory, protective, participates in excretion, maintains the constancy of the internal environment of the body.

The adult body contains about 5 liters of blood, on average 6-8% of body weight. Part of the blood (about 40%) does not circulate through the blood vessels, but is located in the so-called blood depot (in the capillaries and veins of the liver, spleen, lungs and skin). The volume of circulating blood can change due to changes in the volume of deposited blood: during muscular work, during blood loss, under conditions of low atmospheric pressure, blood from the depot is released into the bloodstream. Loss 1/3- 1/2 blood volume can lead to death.

Blood is an opaque red liquid consisting of plasma (55%) and suspended cells and formed elements (45%) - red blood cells, leukocytes and platelets.

1.1. Blood plasma

Blood plasma contains 90-92% water and 8-10% inorganic and organic substances. Inorganic substances make up 0.9-1.0% (ions Na, K, Mg, Ca, CI, P, etc.). An aqueous solution, which in terms of salt concentration corresponds to blood plasma, is called physiological solution. It can be introduced into the body if there is a lack of fluid. Among the organic substances in plasma, 6.5-8% are proteins (albumin, globulins, fibrinogen), about 2% are low molecular weight organic substances (glucose - 0.1%, amino acids, urea, uric acid, lipids, creatinine). Proteins, along with mineral salts, maintain acid-base balance and create a certain osmotic pressure in the blood.

1.2. Formed elements of blood

1 mm of blood contains 4.5-5 million. red blood cells. These are anucleate cells, having the shape of biconcave disks with a diameter of 7-8 microns, a thickness of 2-2.5 microns (Fig. 1). This cell shape increases the surface area for the diffusion of respiratory gases, and also makes red blood cells capable of reversible deformation when passing through narrow curved capillaries. In adults, red blood cells are formed in the red bone marrow of the spongy bones and, when released into the bloodstream, lose their nucleus. The circulation time in the blood is about 120 days, after which they are destroyed in the spleen and liver. Red blood cells can also be destroyed by tissues of other organs, as evidenced by the disappearance of “bruises” (subcutaneous hemorrhages).

Red blood cells contain protein - hemoglobin, consisting of protein and non-protein parts. Non-protein part (heme) contains iron ion. Hemoglobin forms a weak connection with oxygen in the capillaries of the lungs - oxyhemoglobin. This compound is different in color from hemoglobin, so arterial blood(oxygenated blood) has a bright scarlet color. Oxyhemoglobin that gives up oxygen in tissue capillaries is called restored. He is in venous blood(oxygen-poor blood), which has a darker color than arterial blood. In addition, venous blood contains an unstable compound of hemoglobin with carbon dioxide - carbhemoglobin. Hemoglobin can combine not only with oxygen and carbon dioxide, but also with other gases, such as carbon monoxide, forming a strong compound carboxyhemoglobin. Carbon monoxide poisoning causes asphyxiation. When the amount of hemoglobin in red blood cells decreases or the number of red blood cells in the blood decreases, anemia occurs.

Leukocytes(6-8 thousand/mm of blood) - nuclear cells 8-10 microns in size, capable of independent movements. There are several types of leukocytes: basophils, eosinophils, neutrophils, monocytes and lymphocytes. They are formed in the red bone marrow, lymph nodes and spleen, and are destroyed in the spleen. The lifespan of most leukocytes is from several hours to 20 days, and that of lymphocytes is 20 years or more. In acute infectious diseases, the number of leukocytes increases rapidly. Passing through the walls of blood vessels, neutrophils phagocytize bacteria and tissue breakdown products and destroy them with their lysosomal enzymes. Pus consists mainly of neutrophils or their remains. I.I. Mechnikov named such leukocytes phagocytes, and the very phenomenon of absorption and destruction of foreign bodies by leukocytes is phagocytosis, which is one of the body’s protective reactions.

Rice. 1. Human blood cells:

A- red blood cells, b- granular and non-granular leukocytes , V - platelets

Increase in number eosinophils observed in allergic reactions and helminthic infestations. Basophils produce biologically active substances - heparin and histamine. Basophil heparin prevents blood clotting at the site of inflammation, and histamine dilates capillaries, which promotes resorption and healing.

Monocytes- the largest leukocytes; their ability to phagocytosis is most pronounced. They become of great importance in chronic infectious diseases.

Distinguish T lymphocytes(formed in the thymus gland) and B lymphocytes(formed in red bone marrow). They perform specific functions in immune reactions.

Platelets (250-400 thousand/mm3) are small anucleate cells; participate in blood clotting processes.

Internal environment of the body

The vast majority of cells in our body function in a liquid environment. From it, cells receive the necessary nutrients and oxygen, and they secrete the products of their vital activity into it. Only the top layer of keratinized, essentially dead, skin cells borders on air and protects the liquid internal environment from drying out and other changes. The internal environment of the body consists of tissue fluid, blood and lymph.

Tissue fluid is a liquid that fills small spaces between the cells of the body. Its composition is close to blood plasma. When blood moves through capillaries, plasma components constantly penetrate through their walls. This creates tissue fluid that surrounds the cells of the body. From this fluid, cells absorb nutrients, hormones, vitamins, minerals, water, oxygen, and release carbon dioxide and other waste products into it. Tissue fluid is constantly replenished by substances penetrating from the blood and turns into lymph, which enters the blood through lymphatic vessels. The volume of tissue fluid in humans is 26.5% of body weight.

Lymph(lat. lympha- pure water, moisture) - a liquid circulating in the lymphatic system of vertebrates. It is a colorless, transparent liquid, similar in chemical composition to blood plasma. The density and viscosity of lymph is less than that of plasma, pH 7.4 - 9. Lymph flowing from the intestines after eating a meal rich in fat is milky white and opaque. Lymph contains no red blood cells, but many lymphocytes, a small number of monocytes and granular leukocytes. Lymph does not contain platelets, but it can clot, although more slowly than blood. Lymph is formed due to the constant flow of fluid into tissues from plasma and its transition from tissue spaces to lymphatic vessels. Most lymph is produced in the liver. Lymph moves due to the movement of organs, contraction of body muscles and negative pressure in the veins. Lymph pressure is 20 mm of water. Art., can increase to 60 mm of water. Art. The volume of lymph in the body is 1 - 2 liters.

Blood is a liquid connective (support-trophic) tissue, the cells of which are called formed elements (erythrocytes, leukocytes, platelets), and the intercellular substance is called plasma.

Main functions of blood:

transport(transfer of gases and biologically active substances);
trophic(nutrient delivery);
excretory(removal of metabolic end products from the body);
protective(protection from foreign microorganisms);
regulatory(regulation of organ functions due to the active substances that it carries).

The total amount of blood in the body of an adult is normally 6 - 8% of body weight and approximately equal to 4.5 - 6 liters. At rest, the vascular system contains 60-70% of the blood. This is circulating blood. The other part of the blood (30 - 40%) is contained in special blood depots(liver, spleen, subcutaneous fatty tissue). This is deposited, or reserve, blood.

The liquids that make up the internal environment have a constant composition - homeostasis . It is the result of a mobile equilibrium of substances, some of which enter the internal environment, while others leave it. Due to the small difference between the intake and consumption of substances, their concentration in the internal environment continuously fluctuates from... to.... Thus, the amount of sugar in the blood of an adult can range from 0.8 to 1.2 g/l. More or less than normal amounts of certain blood components usually indicate the presence of a disease.

Examples of homeostasis

Consistency of blood glucose levels	Constancy of salt concentration	Constancy of body temperature
The normal blood glucose concentration is 0.12%. After eating, the concentration increases slightly, but quickly returns to normal thanks to the hormone insulin, which lowers the concentration of glucose in the blood. In diabetes mellitus, insulin production is impaired, so patients must take artificially synthesized insulin. Otherwise, glucose concentrations may reach life-threatening levels.	The normal concentration of salts in human blood is 0.9%. The saline solution (0.9% sodium chloride solution) used for intravenous infusions, rinsing the nasal mucosa, etc. has the same concentration.	The normal human body temperature (when measured in the armpit) is 36.6 ºС; a temperature change of 0.5-1 ºС during the day is also considered normal. However, a significant change in temperature poses a threat to life: a decrease in temperature to 30 ºС causes a significant slowdown in biochemical reactions in the body, and at temperatures above 42 ºС protein denaturation occurs.

Any organism - unicellular or multicellular - needs certain conditions of existence. These conditions are provided to organisms by the environment to which they have adapted during evolutionary development.

The first living formations arose in the waters of the World Ocean, and sea water served as their habitat. As living organisms became more complex, some of their cells became isolated from the external environment. So part of the habitat ended up inside the organism, which allowed many organisms to leave the aquatic environment and begin to live on land. The salt content in the internal environment of the body and in sea water is approximately the same.

The internal environment for human cells and organs is blood, lymph and tissue fluid.

Relative constancy of the internal environment

In the internal environment of the body, in addition to salts, there are a lot of different substances - proteins, sugar, fat-like substances, hormones, etc. Each organ constantly releases the products of its vital activity into the internal environment and receives from it the substances it needs. And, despite such active exchange, the composition of the internal environment remains practically unchanged.

The fluid leaving the blood becomes part of the tissue fluid. Most of this fluid returns to the capillaries before they connect with the veins that return blood to the heart, but about 10% of the fluid does not enter the vessels. The walls of capillaries consist of a single layer of cells, but there are narrow gaps between adjacent cells. The contraction of the heart muscle creates blood pressure, causing water with dissolved salts and nutrients to pass through these gaps.

All body fluids are connected to each other. The extracellular fluid comes into contact with the blood and the cerebrospinal fluid that bathes the spinal cord and brain. This means that the regulation of the composition of body fluids occurs centrally.

Tissue fluid washes cells and serves as a habitat for them. It is constantly renewed through the system of lymphatic vessels: this fluid is collected in vessels, and then through the largest lymphatic vessel it enters the general bloodstream, where it mixes with the blood.

Blood composition

The well-known red liquid is actually tissue. For a long time, blood was recognized as a powerful force: sacred oaths were sealed with blood; the priests made their wooden idols “cry blood”; The ancient Greeks sacrificed blood to their gods.

Some philosophers of Ancient Greece considered blood to be the carrier of the soul. The ancient Greek physician Hippocrates prescribed the blood of healthy people to the mentally ill. He thought that in the blood of healthy people there is a healthy soul. Indeed, blood is the most amazing tissue of our body. Blood mobility is the most important condition for the life of the body.

About half of the blood volume is its liquid part - plasma with salts and proteins dissolved in it; the other half consists of various formed elements of blood.

Blood cells are divided into three main groups: white blood cells (leukocytes), red blood cells (erythrocytes) and platelets, or platelets. All of them are formed in the bone marrow (the soft tissue that fills the cavity of long bones), but some leukocytes are able to multiply when they leave the bone marrow. There are many different types of white blood cells - most are involved in protecting the body from disease.

Blood plasma

100 ml of healthy human plasma contains about 93 g of water. The rest of the plasma consists of organic and inorganic substances. Plasma contains minerals, proteins, carbohydrates, fats, metabolic products, hormones and vitamins.

Plasma minerals are represented by salts: chlorides, phosphates, carbonates and sulfates of sodium, potassium, calcium and magnesium. They can be in the form of ions or in a non-ionized state. Even a slight disturbance in the salt composition of plasma can be detrimental to many tissues, and above all to the cells of the blood itself. The total concentration of mineral soda, proteins, glucose, urea and other substances dissolved in plasma creates osmotic pressure. Thanks to osmotic pressure, fluid penetrates through cell membranes, which ensures the exchange of water between blood and tissue. The constancy of the osmotic pressure of the blood is important for the life of the body's cells. The membranes of many cells, including blood cells, are also semi-permeable.

Red blood cells

Red blood cells are the most numerous blood cells; their main function is to transport oxygen. Conditions that increase the body's need for oxygen, such as living at high altitudes or constant physical activity, stimulate the production of red blood cells. Red blood cells live in the bloodstream for about four months, after which they are destroyed.

Leukocytes

Leukocytes, or white blood cells of irregular shape. They have a nucleus embedded in a colorless cytoplasm. The main function of leukocytes is protective. Leukocytes are not only carried by the bloodstream, but are also capable of independent movement with the help of pseudopods (pseupododes). Penetrating through the walls of capillaries, leukocytes move towards the accumulation of pathogenic microbes in the tissue and, with the help of pseudopods, capture and digest them. This phenomenon was discovered by I.I. Mechnikov.

Platelets, or blood platelets

Platelets, or blood platelets are very fragile, easily destroyed when blood vessels are damaged or when blood comes into contact with air.

Platelets play an important role in blood clotting. Damaged tissue releases histomine, a substance that increases blood flow to the damaged area and promotes the release of fluid and proteins of the blood coagulation system from the bloodstream into the tissue. As a result of a complex sequence of reactions, blood clots quickly form, stopping the bleeding. Blood clots prevent bacteria and other foreign factors from entering the wound.

The mechanism of blood clotting is very complex. Plasma contains a soluble protein, fibrinogen, which, during blood clotting, turns into insoluble fibrin and precipitates in the form of long threads. From the network of these threads and blood cells that linger in the network, a thrombus.

This process occurs only in the presence of calcium salts. Therefore, if calcium is removed from the blood, the blood loses its ability to clot. This property is used in canning and blood transfusions.

In addition to calcium, other factors also take part in the coagulation process, such as vitamin K, without which the formation of prothrombin is disrupted.

Blood functions

Blood performs various functions in the body: it delivers oxygen and nutrients to cells; carries away carbon dioxide and metabolic end products; participates in the regulation of the activities of various organs and systems through the transfer of biologically active substances - hormones, etc.; helps maintain the constancy of the internal environment - chemical and gas composition, body temperature; protects the body from foreign bodies and harmful substances, destroying and neutralizing them.

The body's protective barriers

The body's protection from infections is ensured not only by the phagocytic function of leukocytes, but also by the formation of special protective substances - antibodies And antitoxins. They are produced by leukocytes and tissues of various organs in response to the introduction of pathogens into the body.

Antibodies are protein substances that can glue microorganisms together, dissolve or destroy them. Antitoxins neutralize poisons secreted by microbes.

Protective substances are specific and act only on those microorganisms and their poisons under the influence of which they were formed. Antibodies can remain in the blood for a long time. Thanks to this, a person becomes immune to certain infectious diseases.

Immunity to diseases due to the presence of special protective substances in the blood and tissues is called immunity.

The immune system

Immunity, according to modern views, is the body's immunity to various factors (cells, substances) that carry genetically alien information.

If any cells or complex organic substances appear in the body that differ from the cells and substances of the body, then thanks to immunity they are eliminated and destroyed. The main task of the immune system is to maintain the genetic constancy of the organism during ontogenesis. When cells divide due to mutations in the body, cells with an altered genome are often formed. To ensure that these mutant cells do not lead to disturbances in the development of organs and tissues during further division, they are destroyed by the body’s immune systems.

In the body, immunity is ensured due to the phagocytic properties of leukocytes and the ability of some body cells to produce protective substances - antibodies. Therefore, by its nature, immunity can be cellular (phagocytic) and humoral (antibodies).

Immunity to infectious diseases is divided into natural, developed by the body itself without artificial interventions, and artificial, resulting from the introduction of special substances into the body. Natural immunity manifests itself in a person from birth ( congenital) or occurs after illnesses ( acquired). Artificial immunity can be active or passive. Active immunity is developed when weakened or killed pathogens or their weakened toxins are introduced into the body. This immunity does not appear immediately, but persists for a long time - several years and even a lifetime. Passive immunity occurs when a therapeutic serum with ready-made protective properties is introduced into the body. This immunity is short-lived, but appears immediately after administration of the serum.

Blood clotting also refers to the body's protective reactions. It protects the body from blood loss. The reaction consists of the formation of a blood clot - thrombus, which seals the wound area and stops bleeding.

Blood plasma consists of: water, mineral salts, nutrients, vitamins, antibodies, hormones, toxic substances, oxygen, carbon dioxide, etc. The components are: red blood cells, leukocytes, platelets. Red blood cells = red blood cells = red blood cells. These are nuclei, with the exception of mammals with germ and germ cells in the primary phases. They are disc-shaped, flattened in the middle region. Because they do not have a nucleus, they can incorporate more hemoglobin - a respiratory pigment - a protein with iron = heteroprotein.

Tissue fluid is a liquid that fills small spaces between the cells of the body. Its composition is close to blood plasma. When blood moves through capillaries, plasma components constantly penetrate through their walls. This creates tissue fluid that surrounds the cells of the body. From this liquid, cells absorb nutrients, hormones, vitamins, minerals, water, oxygen, and release carbon dioxide and other waste products into it. Tissue fluid is constantly replenished by substances penetrating from the blood and turns into lymph, which enters the blood through lymphatic vessels. The volume of tissue fluid in humans is 26.5% of body weight.

It is formed in combination with oxygen and carbon dioxide, labile compounds: oxyhemoglobin and carbohemoglobin. Role: Transports respiratory gases. Leukocytes = white blood cells. They are germ cells of different shapes and types: - polynuclear - have different shaped nuclei - secrete pseudopods - phagocyte pathogens - perform diapesis They can be neutrophils, acidophiles and basophils depending on their affinity for neutral, acidic or basic dyes. - Mononuclear.

Lymphocytes - produce antibodies. Monocytes remain in the bloodstream for a short period of time, then pass into the tissue and become macrophages, which have the ability to phagocytose and are large in size. Role: White globules play a role in protecting the body from pathogens. The polymorphonuclear product causes phagocytosis, that is, it includes pseudopod pathogens. Lymphocytes produce antibodies that destroy antigens.

Lymph(lat. lympha- pure water, moisture) - a liquid circulating in the lymphatic system of vertebrates. It is a colorless, transparent liquid, similar in chemical composition to blood plasma. The density and viscosity of lymph is less than plasma, pH 7.4 - 9. Lymph flowing from the intestines after eating a meal rich in fat is milky white and opaque. Lymph contains no red blood cells, but many lymphocytes, a small number of monocytes and granular leukocytes. Lymph does not contain platelets, but it can clot, although more slowly than blood. Lymph is formed due to the constant flow of fluid into tissues from plasma and its transition from tissue spaces to lymphatic vessels. Most lymph is produced in the liver. Lymph moves due to the movement of organs, contraction of body muscles and negative pressure in the veins. Lymph pressure is 20 mm of water. Art., can increase to 60 mm of water. Art. The volume of lymph in the body is 1 - 2 liters.

Platelets are cellular fragments with cytoplasm and membrane. They interfere with blood clotting, which is a mechanism of homeostasis. The molded elements are formed at the level of the red bone marrow. It is formed from interstitial fluid, from where it restores substances beneficial to the body.

The heart is located in the chest cavity between the two lungs. It is tetracameral, has a conical shape, the point is turned to the left. Each atrium communicates with the ventricle on the same side through an atrioventricular orifice, equipped with a tricuspid valve on the right and a bicuspid valve on the left.

Blood is a liquid connective (support-trophic) tissue, the cells of which are called formed elements (erythrocytes, leukocytes, platelets), and the intercellular substance is called plasma.

Main functions of blood:
The heart represents: - endocardial - internal, consisting of thin epithelium located on very thin connective tissue; - myocardium - the heart muscles are more developed in the ventricles; - epicardium - external, is the inner sheet of the pericardium. The pericardium promotes gliding during heart contractions.

Nodular or excitoconductive tissue is located in the myocardium and consists of muscle fibers specialized in the development and treatment of stimuli that provide cardiac automaticity. The vascularization of the heart is provided by two coronary arteries, which are separated from the base of the aorta. Venous blood is collected from the coronary veins. The heart functions as a double pump, providing circulation in two circuits: the systemic or systemic circulation and the pulmonary or pulmonary circulation.

transport(transfer of gases and biologically active substances);
trophic(nutrient delivery);
excretory(removal of metabolic end products from the body);
protective(protection from foreign microorganisms);
regulatory(regulation of organ functions due to the active substances that it carries).

Blood vessels: - arteries - leave the ventricles and carry blood to the organs - veins - open in the atria and bring blood from the organ to the heart - have thin walls; their wall is without elastic fibers. Capillary - performs gas exchange at the organ level.

Blood pressure on the arterial wall is blood pressure: - no more than 120 mm Hg. And min. 70 mmHg Once oxygenated, the blood returns to the left atrium through the pulmonary veins. The systemic circulation begins from the left ventricle through the aortic artery, which forms the aortic crank on the left as it exits the heart.

The aortic artery carries oxygenated blood to the tissues, and blood with carbon dioxide returns to the heart through the superior and inferior veins, which open into the right atrium. Blood is a fluid that circulates inside the cardiovascular shaft. Together with lymph and intracellular fluid, blood is the internal environment of the body.

The content of the internal environment, both in nutrients and in catabolic products, is constantly maintained due to constant blood circulation. It brings beneficial substances to the vicinity of the cells, always restores metabolic reserves and therefore removes catabolic products that they carry to the elimination organs.

Examples of homeostasis

Consistency of blood glucose levels

Constancy of salt concentration

Constancy of body temperature

The normal blood glucose concentration is 0.12%. After eating, the concentration increases slightly, but quickly returns to normal thanks to the hormone insulin, which lowers the concentration of glucose in the blood. In diabetes mellitus, insulin production is impaired, so patients must take artificially synthesized insulin. Otherwise, glucose concentrations may reach life-threatening levels.

The total amount of blood in the body is 7% of body weight. This means that 5 liters of blood for a person is 70 kg. This is a stagnant or reserve blood volume of 2 liters. The remaining 3 liters is the volume of circulating blood. The relationship between circulating volume and stagnant volume is not fixed, but varies depending on living conditions. During physical or thermoregulatory exercises, reserve blood is mobilized and circulation volume increases. This ensures an optimal supply of oxygen and energy to active organs.

The normal concentration of salts in human blood is 0.9%. The saline solution (0.9% sodium chloride solution) used for intravenous infusions, rinsing the nasal mucosa, etc. has the same concentration.

The normal human body temperature (when measured in the armpit) is 36.6 ºС; a temperature change of 0.5-1 ºС during the day is also considered normal. However, a significant change in temperature poses a threat to life: a decrease in temperature to 30 ºС causes a significant slowdown in biochemical reactions in the body, and at temperatures above 42 ºС protein denaturation occurs.

Blood is red. It is related to the hemoglobin in red blood cells. The color of blood can vary under physiological or pathological conditions. Blood collected in the arteries is light red, while blood drawn from the veins is dark red. When the amount of hemoglobin in the blood decreases, the color becomes reddish-pale. Blood is heavier than water. Blood plasma has a density of 1. This property of blood depends on its components and especially on the liver and protein.

Viscosity. The relative viscosity of blood is 4.5 relative to the viscosity of water, which is considered equal to the viscosity, ensuring laminar blood flow through the vessels. An increase in viscosity over certain values is a circulation factor. Osmotic pressure. In any solution, additional static pressure arises, which can be emphasized by separating the solvent of this solution through a semi-permeable membrane. Under these conditions, the phenomenon of osmosis consists of the movement of solvent molecules through a membrane into the compartment occupied by a solution; in the case of dilute solutions, the value of osmotic pressure is equal to the pressure of an ideal gas, which at a given temperature will occupy the volume of the solution and will contain an equal number of moles with dissolved substances.

The unit of osmotic pressure is the osmole per liter or its subunit, milliosmole per liter. Osmol is the osmotic pressure of one mole of a non-ionizable substance. Osmotic pressure plays an important role in the metabolism between capillaries and tissues. The osmotic pressure of colloidal substances is called colloid osmotic pressure and has a very low value of only 28 mm Hg. However, plasma proteins play a very large role in the exchange of capillary tissue, because the osmotic blood pressure is equal to that of the interstitial fluid, and the only force that removes water from the tissues into the capillaries is the colloid osmotic pressure of plasma proteins.

1. Composition and functions of blood

Blood performs the following functions: transport, heat distribution, regulatory, protective, participates in excretion, maintains the constancy of the internal environment of the body.

Another role of colloid osmotic pressure is in the process of glomerular ultrafiltration leading to urine formation. Therefore, eight percent is isotonic and is called saline solutions. The blood reaction is poorly alkaline. All values greater than 7 represent an alkaline reaction and less than 7 an acid reaction, blood phylloids are kept constant around 7.35 due to the existence of physicochemical and biological control mechanisms. Physicochemical mechanisms include electron buffer systems and biological mechanisms of lung, kidney, liver and hematite.

Blood is an opaque red liquid consisting of plasma (55%) and suspended cells and formed elements (45%) - red blood cells, leukocytes and platelets.

1.1. Blood plasma

Buffers quickly intervene to neutralize excess acids or bases in the internal environment. They are consumed during moaning. Biological mechanisms interfere more slowly and result in both the removal of acids or bases and the restoration of buffer systems.

An anti-acid buffer system is a pair of two substances consisting of a weak acid and its salt having a strong base. Temperature. The continuous movement of blood through the body promotes uniformity of body temperature and helps transfer heat from the internal organs to the skin, where it is eliminated by irradiation.

1.2. Formed elements of blood

Thus, the "cooled" blood returns to the deep bodies, where it rehearses with heat, and so on. The human body is a complex biological system that includes the following levels of organization. Atomic cell molecular tissue organ organs. . All these structures interact and implement the vital functions of the body.

Reproductive nutrition relationships.
Ectoblast mesoblast endoblast.

By differentiating cells from the embryonic foliage, the organs, organs and organ systems of the embryo arise. Soft connective tissues. Digestive system respiratory system thyroid gland, parathyroids, tonsils thymus. Spinal lymph nodes, nerve cranials, and autonomic lymph nodes.

Epidermis and its corneal and glandular nervous system with: neural tube.
Neurophysiophysis and epithelial retina and pigment layer.
Previous pituitary gland = adenohypophysis.

Its main function is to support and protect the body.

It is a passive component of the locomotor system. It is the body's primary systemic effector. It is an active component of the locomotor system. It receives, transmits and integrates information received from the external or internal environment, realizing the coordination and integration of the organism into its environment.

It carries out gas exchange between the body and the environment. It is a transport system for nutrients, respiratory gases, and non-toxic or toxic products. It coordinates and controls the growth and development of the organism and interacts with the nervous system, adapting and integrating the organism into its environment.

It plays a role in digestion and absorption of nutrients and elimination of inevitable residues. By producing gametes and sex hormones, it ensures the perpetuation of species. The human body is three-dimensional and has bilateral symmetry. Vertically positioned and oriented parallel to the forehead; passes through the longitudinal and transverse axes. Perpendicular to the front and crosses the body backward, passing through the longitudinal and sagittal axes; passes through the middle of the body as a plane of symmetry; examples: the eyes are located sideways to the nose and medial to the ears. Perpendicular to the frontal and sagittal and passes through the sagittal and transverse axes; divide the body into: upper and lower parts: the nose is cranial-mouth, and the knee is located caudal to the thigh.

Share your body in the front and back.
Examples: The nose is located forward and the spine.

Blood, lymphatic and intercellular fluids form the internal environment of the body, characterized by relatively constant physicochemical properties that provide the necessary homeostasis for normal cell activity.

Rice. 1. Human blood cells:

A- red blood cells, b- granular and non-granular leukocytes , V - platelets

Monocytes- the largest leukocytes; their ability to phagocytosis is most pronounced. They become of great importance in chronic infectious diseases.

Distinguish T lymphocytes(formed in the thymus gland) and B lymphocytes(formed in red bone marrow). They perform specific functions in immune reactions.

Platelets (250-400 thousand/mm3) are small anucleate cells; participate in blood clotting processes.