The smallest amount of blood in a person is normal. How much blood is in the human body and what does it depend on? Functions of the circulatory system

Blood mass in the body

(see Anemia) - presents rather sharp fluctuations, depending mainly on the size of the diameter of the vessels and the capacity of the heart (Beneke). All attempts to determine blood M. both in animals and in humans give only approximate results. More accurate than others is Welker's method of direct determination of blood M, used on animals of various classes and on executed criminals: large arterial trunks are opened and the blood directly flowing from them is collected (I). Then the remainder of the blood from the vessels is washed with water until a colorless liquid flows out of the veins and in this latter is determined by comparing its red color with the color of the liquid containing a certain volume of blood, the amount of blood in the washing liquid (I); and finally, aqueous extracts are made from tissues and organs, into which the last remnants of blood are transferred, also determined colorimetrically (III). Sum I + II + III = all M. blood. He gave for humans, dogs, mice the numbers of M. blood equal to 1/12 - 1/13 of body weight, for a rabbit 1/18, for a cat 1/22, for a frog 1/15 (Ranke), in birds (chickens) up to 1/10 of body weight, and in diving birds, especially ducks, the amount is even greater (P. Behr). It is possible, on the basis of a simple calculation, to theoretically determine the M. of blood in a person (Vierordt), namely: since during a full circulation of blood throughout the body, all of it passes one once through the left ventricle of the heart, then knowing time full revolution = 23.1 sec., number heartbeat at this time = 27.7 systole and quantity of blood pushed out into the artery by each systole = 172 cubic meters. cm, all M. blood = 172 × 27.7 = 4760 cubic meters. cm, i.e. approx. 5020 g; if the average weight of a person is taken to be 63 kg, then M. blood will be equal to 1/12.6 of body weight, a number that coincides almost with Welker’s most accurate measurements. Several indirect methods for determining blood M. have been proposed, applicable to animals without depriving them of life; Of these, the most noteworthy is the method based on determining blood hemoglobin before and after diluting it with a certain volume of an indifferent colorless solution (Tsibulsky); another, based on determining the amounts of carbon monoxide associated with an animal during incomplete combustion (Gréhant and Quinquaud), and finally, a method based on thickening the blood by sweating and determining the amount of hemoglobin before and after thickening (Tarkhanov). These methods, of which the last one is applied to humans, yielded numbers that were close and almost identical to the data from Welker’s direct method. Blood volume depends on a number of factors: 1) on the diameter of the blood vessels and the capacity of the heart with fluctuations of 1/3 and even 1/2 in either direction (Beneke); 2) depending on age - young individuals have relatively more M. blood than adults (Ranke, Malyase, Schüking); 3) from nutrition - during the period of digestion, blood volume can almost double (Claude Bernard); during the period of fasting, the absolute amount of blood drops sharply, but its relative content even increases (Panum et al.); 4) from the fatness of the individual - obese fatty individuals contain relatively less blood than thinner, skinny subjects; 5) from muscle exercises - they usually contribute to the growth of M. blood in the body (Rank); 6) depending on the type of food - meat, apparently, contributes to an increase in blood mass compared to plant foods; 7) depending on the type of animal - cold-blooded animals usually have less blood mass than warm-blooded animals, and among the latter, birds have the largest blood mass due to their high metabolism. Diving birds have the greatest amount of blood, and this is extremely important for them due to the need to have a larger supply of oxygen during their diving, since with more blood in the body there is more hemoglobin, which binds oxygen. Blood in round numbers is distributed as follows: about 1/4 of all M. blood is in the heart, lungs, large arteries and veins; about 1/4 in the liver, about 1/4 in the skeletal muscles, the remaining 1/4 in other organs of the body. The percentage of blood in different organs varies: the heart, lungs and large blood vessels contain about 63% of the blood; behind them, according to the percentage of blood, comes the liver - 28.71%, then the spleen - 12.5%, kidneys - 11.86%, brain - 5.52%, muscles - 5.14%, digestive canal - 3, 46%, bones - 2.36%, skin - 1.07% (Ranke). This distribution of blood fluctuates depending on the activity of the organs. Blood flows intensely to every organ during its operation; During muscle tetanus in frogs, rabbits, etc., the muscles are enriched with more than 30% blood, but the blood vessels and glandular system are depleted of it by more than 20% and so much so that, for example. the glandular apparatus in tetanized animals almost does not function at all, the kidneys do not filter urine, digestive juices almost cease to be secreted; During digestion, the muscular system is anemic, while the glands, on the contrary, become engorged with blood. This is the basis for the alternating activity of organs (Ranke), i.e., the phenomenon according to which all organ systems cannot work energetically at the same time. This distribution of blood among the organs of the body is controlled by the system of vasomotor nerves - vasoconstrictor and vasodilator (see Heart, Vessels, their innervation). A loss of blood approximately equal to half the weight of M. blood is considered fatal for a person, i.e., a loss of 5-6 pounds. for an adult.

Wed. Welcker ("Prager Vierteljahresschrift" for 1854 and "Zeitschrift f rat. Medicin" for 1858); Wagner's "Handwörterbuch d. Physiologie" (vol. I); Tarkhanov, "Determination of M. blood on a living person" ("Doctor", for 1880 and Pflüger's "Archiv", vols. 23 and 24); Chiryev, "Blood Statics".

AND. T.

Encyclopedic Dictionary F.A. Brockhaus and I.A. Efron. - S.-Pb.: Brockhaus-Efron. 1890-1907 .

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Blood is an essential component of the internal environment of the human body. Due to its constant movement through the vessels, metabolism is carried out in organs and tissues.

Compound

Blood is a liquid connective tissue, which includes cells or formed elements (leukocytes, erythrocytes, platelets) and intercellular substance (plasma).

On average, formed elements account for about 40-45% of blood, and plasma - 55-60%. Laboratory analysis shows all deviations from the norm and indicates the presence of a particular disease. Depending on how many liters of blood there are in a person, the number of its constituent elements may be different. Its composition may also be influenced by health status and geographic location. For example, when you rise to a height, the number of red blood cells increases significantly. Residents of the Caucasus or Switzerland have 50 percent more red blood cells than England or other highland areas. Blood moves through the vessels at a speed of 40 kilometers per hour.

Functions

The main functions of blood are determined by its composition.

Due to plasma, which is an aqueous solution of proteins, fats, carbohydrates, amino acids, vitamins, hormones, as well as inorganic (mineral) substances, the function of transporting water and nutrients to tissues and organs and removing metabolic products is carried out. Thanks to the viscosity that proteins impart to the plasma, blood pressure is maintained at the desired level. A certain composition of plasma ensures the constancy of its internal environment in the body. Each blood element also performs a specific function:

Erythrocytes (red blood cells) carry oxygen throughout the body. They cause the red color of blood.

White blood cells (colorless cells) perform the function of protecting the body by fighting foreign bodies (including viruses, bacteria, cell fragments, particulate matter, allergens and toxins). There are several types of leukocytes. Each of them is responsible for the destruction of a certain type of foreign body. Based on their ratio, leukocyte formulas are compiled, which indicate the presence of a particular harmful agent in the body. White blood cells produce certain antibodies that make the body immune to infectious diseases. The doctrine of human immunity, as well as the creation of vaccinations and serums to combat severe infections, is based on this property.

Platelets are blood cells that provide blood clotting. This ability allows you to avoid large blood losses as a result of various types of injuries. Disruption of the activity of these cells is often associated with genetic changes and leads to dire consequences, when even the most harmless cut or scratch can become deadly.

Blood groups

Human blood is divided into 4 groups: the first - O, the second - A, the third - B, the fourth - AB. This classification was introduced in 1900 by K. Landsteiner, it is called the ABO system. This division of blood is based on the content or absence of erythrocyte antigens A and B, as well as plasma antibodies A and B. Blood transfusions are carried out taking into account the compatibility of the groups with each other. Each group, in turn, can be of two types: Rh-positive and Rh-negative. This feature is very important for couples planning to have a child, since in some cases Rh conflict may arise. As a result, pregnancy and gestation become problematic.

How many liters of blood does a person have? Factors influencing the indicator

The question of how many liters of blood is in a person cannot be answered unambiguously. It is believed that this indicator depends on the individual characteristics of the body, body weight, age, gender and physical condition of the body. In general, the norm for an adult is approximately 4-6 liters (6-8% of the total body weight). Thus, if a person has a mass of 65 kg, then he will have approximately 3.9-5.2 liters. Most of the blood constantly circulates through the vessels, and some of it (up to 40%) is located in the so-called “blood depots” of the body. These are the liver, spleen, lungs, skin, etc. With strong muscle loads, large blood losses, and a decrease in atmospheric pressure, it leaves a kind of depot.

Amount of blood in a person

In women, the volume of circulating blood is 4-4.5 liters, in men - 5-5.5 liters. Its amount may vary depending on the volume of fluid drunk, during menstruation and pregnancy, with blood loss due to injuries and operations, and with heavy physical exertion. The amount of blood in children of different age groups differs significantly. In relation to body weight, the following indicators are considered normal:

15% - in newborns;
11% - in one-year-old children;
9% - in adolescence.

Safe minimum

How many liters of blood should a person have so that there is no threat to life? It is believed that if a person loses 2-3 liters, he dies. This can happen for many reasons. Among them are sudden and heavy bleeding, operations and the postoperative period, treatment of various diseases, hemodialysis.

To save lives, in medicine they often resort to the procedure of donor transfusion. A person who donates his blood to help others is called a donor. It is believed that the one-time safe volume that is taken from him is 450 ml of blood, and plasma - 600 ml. You can donate plasma no more than 2 times a month, and blood no more than 1 time a month. During this time, the quantitative and qualitative blood composition is completely restored. Each institution that collects donor blood compiles its own database. There are a number of diseases for which it is contraindicated to be a donor. To identify such facts, everyone's blood is taken for a special analysis.

Dangerous situations

A blood loss of 20-40% of the total is considered life-threatening. Most people experience heart problems, low blood pressure, breathing problems, dizziness or fainting. The following are considered external manifestations: pale skin and coldness of the upper and lower extremities. With blood loss of 50 to 70 percent, convulsions and agony begin, and the chances of survival approach zero. An important factor in blood loss is its speed. For example, a sudden loss of blood in the amount of 2-3 liters in a short period of time is fatal, but a prolonged loss of blood will not be so. However, the second case may be hidden (internal bleeding), which is sometimes difficult to diagnose and entails a huge threat to the bleeding organ and the body as a whole. The symptoms in this case are similar to those described earlier in this article.

Recovery

Self-regeneration of blood is allowed with a loss of no more than 30 percent.

Otherwise, a donor blood transfusion is required. For quick recovery, you need to eat foods rich in iron, including beef and red fish, liver, and also drink a lot. Raisins, dried apricots and nuts are very useful in this regard. Among the drinks, pomegranate juice and a small amount of red wine, tea with sugar and milk are of particular value. Complete self-healing of the blood occurs within two weeks. As a result, it turns out that how many liters of blood a person had before blood loss is approximately the same after the recovery period.

Blood is a liquid tissue consisting of plasma and formed elements. Plasma, which is a colorless liquid, contains cells in suspension: leukocytes, platelets, and red blood cells. The latter give it its characteristic red color. The state of health depends not only on the composition of the blood, but also on how much of it is contained in the human body.

Plasma makes up about 60% of the total volume. If you separate the formed elements from it, then 90% of it will consist of water, the remaining 10% are salts, carbohydrates, proteins, carbon dioxide, oxygen, and bioactive substances. Men always have more plasma than the fairer sex.

Functions

Blood performs essential functions in the human body. It constantly circulates in a system consisting of large and small blood vessels that penetrate all organs and tissues, with the exception of the epithelium of the skin and mucous membranes, articular cartilage, cornea, hair and nails.

Red cells deliver oxygen to tissues due to the ability of hemoglobin to reversibly bind to its molecules. Platelets are directly involved in coagulation during bleeding: they rush to the site of vessel damage and form a blood clot at this site. Leukocytes are the body's main defenders from internal and external harmful agents.

Blood transports oxygen from the lungs to tissue cells, and carbon dioxide from tissues to the lungs, carries metabolic products, nutrients, hormones, enzymes, biologically active substances, and is also responsible for the delivery of final metabolic products to the organs of the excretory system. It regulates temperature and maintains water, electrolyte and acid balance in the body.

How much blood does a person have?

Its volume varies from person to person. It depends on gender, age, weight and individual characteristics. The norm is taken to be from 5 to 9% of body weight. On average, an adult circulates approximately 5-6 liters of blood, and a child, accordingly, has less. Its quantity is maintained by the body at the same level. If there are deviations in one direction or another, health problems arise.

With a sharp decrease in blood volume, blood pressure drops, anemia, necrosis may develop, and brain activity may be impaired. Losing two to three liters in a short period of time can result in the death of a person. As a rule, if half the volume is lost, 98% of people die.

If an increased amount circulates in the system, nosebleeds may occur. Cuts and other injuries in this case take longer to heal, which is due to the greater pressure under which blood flows out of the wound. As a rule, when excess blood forms in the body, it is redistributed. It enters muscle tissue, skin, is processed by the kidneys and is excreted naturally.

In men, about 5-6 liters constantly circulate in the body, in women - about 4-5 liters. In a child’s body, its volume is significantly less than in an adult, and depends on weight and age. Its amount may change periodically, which is associated with bleeding, significant physical activity, injuries, menstruation, and consumption of large amounts of fluid. Women tolerate blood loss much easier than men.

How to determine a person's blood volume?

For this purpose, a certain amount of a contrast agent, usually a harmless dye, is injected into the blood. After it is distributed throughout the riverbed, a fence is made to determine its concentration.

Another way is to inject radioactive isotopes and count the number of red blood cells that contain them. The amount of blood is determined by the level of its radioactivity.

Blood transfusion is used to normalize blood volume in the body.

How to make up for the loss?

Today this problem is solved with the help of donor blood transfusions. This procedure is necessary for severe injuries, surgeries, and childbirth. Most often, plasma is transfused, which makes up about 60% of the total volume. The donor's blood must match the patient's group and Rh factor.

According to the existing law, you can donate no more than 450 ml of blood (or 600 ml of plasma) at a time. In addition, there are restrictions on the frequency of donation and the weight of the donor (4 times a year for women, 5 times for men, the interval between donations is at least 60 days, the donor’s weight is at least 50 kg). This order is due to the fact that the loss of 10% of blood can lead to a deterioration in health and the development of anemia.

Conclusion

Human health depends not only on the composition of the blood, but also on its volume. A significant decrease in its amount in the body can cause illness and even death.

Many people wonder how many liters of blood are in a person? Agree, the question is quite interesting and therefore it is worth understanding it in more detail and in detail, considering its functions and composition, as well as how the loss of blood in the body is restored and, most importantly, how much blood is in the human body.

Blood is a fluid that includes plasma and specific formed components. It is the plasma of both adults and children that contains leukocytes, platelets and red blood cells - the general state of health depends on the normal amount of blood in the human body, which also depends on the qualitative indicator of blood composition. In particular, on average the amount of plasma is equal to 60 percent of the total blood volume in the human body. If we isolate the formed components from it, then 90% is water and only 10% is salts and carbohydrates, proteins, and according to statistics, the amount of plasma in a man’s body is slightly greater than that of a woman.

At the very beginning, it is the blood, or rather the red cells included in its composition, that supply oxygen to organs and tissues - all this occurs due to the property of hemoglobin to bind molecules together. And therefore, depending on how many liters of blood are in a person, the saturation of tissues, organs and the entire body with oxygen depends. The platelet takes an active part in the process of blood clotting in the event of bleeding, rushing to the site of injury and forming a blood clot in the vessel. At the same time, leukocytes in the body of an adult and a child are the main defenders in the body from external and internal contractors.

Blood also supplies oxygen from the lungs, where it is enriched with it into cells, tissues and organs, and in return, it removes carbon dioxide as an metabolic product of the vital activity of human organs. Blood also perfectly regulates the temperature of the body and helps maintain oxygen balance in the human body - if it is insufficient in the human body, the latter experiences general weakness, as well as coldness in the extremities and, in the worst case, the development of anemia, even death.

If we talk about this, then at the very beginning it is worth saying that this volume is purely individual. It may depend on gender, weight category, when a person’s body weighs 50 or 70 or 100 kg, age and other personal properties of the body and varies from 5 to 9 percent of the total body weight.

In the body of an adult, on average, there are 5-6 liters, and in a baby this figure is less - it is this “liter capacity”, so to speak, that helps maintain the entire human body at the same level, and with anomalies in the direction of increasing or decreasing, the person may begin to have certain problems with own health. In the worst case scenario, this situation can be fatal.

For example, if there is more blood in the body than normal, a person may experience bouts of nosebleeds, and cuts, injuries and other injuries take longer to heal, since the pressure of the flowing blood in this case is somewhat higher. When there is an excessive amount of blood in the body, it is redistributed to the skin, muscles and, having been processed by the kidneys, is excreted from the body through the natural excretory tract.

In more detail, for a man this figure is fixed at 5-6 liters of blood, for a woman – 4-5 liters, and for a child even less, depending on age and weight. This figure may vary depending on physical activity or injury, a woman’s menstrual cycle or other factors, while women tolerate blood loss more easily than the stronger sex.

Maximum possible and acceptable blood loss

If we talk about emergency cases, then if an individual loses about 2-3 liters of blood within a short period of time, such a loss can lead to death. In this case, blood loss can lead to the development of a disease such as anemia.

It is also worth noting the fact that for some types of diseases it is necessary to systematically transfuse blood and this is not a good thing in relation to normal human life. If we are talking about surgery, then during surgery, with a standard procedure for a person, an appropriate transfusion may be required in the range of 5 to 8 liters.

Every person understands perfectly well that no matter how many liters of blood are in his body, blood loss is always undesirable and in some cases even harmful. However, this problem can be solved by transfusing the latter from a donor. In particular, this approach is practiced in cases of serious injuries, as well as during surgery or childbirth. At the same time, plasma is transfused into the patient - it is this that makes up 60 percent of the total volume and it must be similar in group and Rh factor compatibility.

According to the current regulations of the law, it is worth noting that if we are talking about donating blood, then for 1 donation the doctor can draw a maximum of 450 ml. blood or no more than 600 ml. plasma per donation from one patient. The law also prescribes certain requirements for the frequency of donation, as well as the body weight of a potential donor. Here the frequency is 4 for women and 5 for men per year, with a time interval of 2 months between each given medical procedure. If we are talking about the weight category of a potential donor, then it must be at least 50 kg and the approach itself and such restrictions are due to the fact that even the loss of 1/10 of the blood leads to the possible development of anemia and a deterioration in general condition and well-being.

How is blood volume determined?

First of all, an established contrast agent is injected into the blood; most of it is a dye that is not harmful to the body. After it is completely distributed throughout the body, blood is taken for analysis to determine its concentration. Another option for determination is the introduction of artificial radioactive isotopes and a standard determination of the number of red blood cells, in which these isotopes are detected and thereby the total amount, so to speak, “liter” of blood in the human body.

To summarize, we can say that the amount of blood in the body is individual for each person and it is quite possible to determine more or less accurately its quantity in the body. It is also worth noting that blood loss is always negative, although its replacement is always possible even in the most difficult situation - the main thing in this case is efficiency, compatibility and medical control at all stages of the procedure.

Video about how many liters of blood are in a person

Blood is the most important part of the human body; it connects all organs and systems with each other. To maintain health, all its characteristics are important: how much blood a person has, its viscosity, cellular composition, saturation with oxygen, nutrients, hormones, and other biologically active components.

Blood composition

It consists of plasma (liquid part) and cells. Normally, plasma, consisting of 90% water and 10% proteins, carbohydrates and fats, and minerals, makes up about 60% of its volume. The rest are formed elements of blood that perform specific functions:

Red blood cells provide gas exchange to tissues - they bring oxygen and take away carbon dioxide. Red bone marrow is the site of production of these cells.
Leukocytes protect the body from the introduction of foreign and infectious microorganisms. Synthesized in lymph nodes, bone marrow, and spleen.
Platelets - determine the ability to clot. Also born in the bone marrow. Due to the presence of iron and copper in these cells, they take part in the transport of oxygen.

Hematocrit

The percentage composition of cells and fluid may change due to exposure to external factors or changes in the internal state of the body. Hematocrit number is an indicator of a blood test that allows you to judge its density.

An increase in hematocrit occurs when the body loses fluid during

diarrhea,
vomiting
increased sweating,
extensive burns.

Blood also thickens with increased production of red blood cells.

A decrease in hematocrit - blood thinning - is observed when

the intake of large amounts of fluid into the body,
disruption of blood cell formation,
their pathological destruction,
pregnancy,
accumulation of fluid in the body due to pathology of the excretory system.

Normal values of the indicator are different for women, men and children:

40-49 – for men;
36-42 – for women;
44-62 - in newborns;
32-44 - in children under 3 months;
36-44 – up to 10 years.

Blood functions

The main one is transport: flowing through vessels of various diameters, it transports substances necessary for the normal functioning of organs; it receives metabolic products that must be removed from the body. Thanks to its composition, it provides tissues

Breath. Oxygen dissolved in the plasma and bound to blood elements is transported from the lungs to the cells that need it with the help of the blood, and carbon dioxide is transferred from the cells to the lungs.
Nutrition. Useful substances - glucose, fats, vitamins, amino acids are transported from the digestive organs to the tissues. Also, when there is a lack of nutrition, the blood delivers the necessary substances from the places where they are deposited.
Release of harmful elements. The end products of cellular metabolism - uric acid, urea and others are transported with the blood to the excretory organs - intestines, kidneys, sweat glands, lungs.
Exchange of biologically active components. The circulation of hormones, signaling molecules, and other active compounds ensures the body’s rapid response to various external and internal changes.
Heat transfer: transfers and redistributes heat and energy.
Homeostasis. The water-salt and acid-base balance of the whole organism remains constant.
Protection. Blood cells carry out immune reactions, prevent the penetration and reproduction of infectious agents and their own defective cells. In case of vascular damage, the coagulation system stops bleeding, and the anticoagulation system helps dissolve thrombotic masses and restore the patency of arteries and veins.

How much blood is there in a person

If a person is healthy, the amount of blood in his body is relatively constant. It depends on gender, age and personality traits. Women, other things being equal, have slightly less blood. Newborns have very little of it - about 300 ml.

They accurately determine how many liters of blood are in a person using special methods if there are medical indications. The average norm is 5-9% of body weight for an adult.

So, if the patient is a man weighing 70 kg, then there is about 5.5 liters of blood in him. A plump woman weighing 90 kg is already the owner of about 7.5 liters.

The amount of blood in the body of each person largely depends on the functioning of his hematopoietic system, which includes

spleen,
red bone marrow,
The lymph nodes.

Interestingly, within a day the hematopoietic system of an individual weighing 60 kg provides the synthesis

2100 billion red blood cells,
2 billion monocytes,
4600 billion neutrophils,
183 billion platelets.

It is estimated that the average body produces about 482 kilograms of red blood cells over a lifetime.

When determining the exact amount of blood in the body, it is necessary to take into account that not all of its volume circulates through the vessels. The body stores it in special depots - in the liver and spleen. And he uses this reserve in emergency situations, when he is under increased stress - both mental and physical.

Also, a certain amount of blood is constantly present in the organs that produce blood cells and in those that utilize them. For red blood cells this is the spleen, for lymphocytes it is the lungs.

Diseases of organs that store blood are normally fraught with deterioration in adaptation to stress.

How is the exact amount of blood determined?

Radioisotope method. A radioactive isotope is injected into the blood, then the number of red blood cells that have captured it is counted. Based on this, the amount of radioactivity in the blood is calculated and its corresponding amount is determined.
Contrast method. A dye is injected intravenously, after a while a blood sample is taken and the contrast concentration is determined. Then the volume is calculated.

In common practice, a quick and simple calculation of the theoretical minimum and maximum blood volumes is most often used. If the patient weighs 80 kg, taking into account the limits of 5-9%, his body can contain from 4 to 7.2 liters.

Blood loss

The loss of a small amount of blood is harmless for a person, and in a certain aspect it is useful - it stimulates the formation of new young cells and eliminates excess.

Medicine indicates the maximum volume of blood, the loss of which can be perceived by the body as a benefit - up to 10%.

Donation is just such a periodic loss that does not adversely affect the health of the one who donates blood and saves the life of the one to whom it is transfused. According to the law, women can donate a maximum of 4 times a year, men - 5. They take no more than 450 ml at a time. The donor's weight cannot be less than 50 kg. You can read more about the blood transfusion procedure.

Blood loss of up to 20% can lead to serious health problems - the heart stops working rhythmically, blood pressure decreases, and the pulse slows down. When bleeding stops at this stage, the body is able to gradually cope with such blood loss and replace it. A transfusion is vital for a person who has lost more than 20% of their blood volume.

The rate of blood loss is also of great importance. Intense bleeding causes more harm than what happens gradually in small portions.

In dangerous situations that are accompanied by the risk of blood loss - during severe injuries, surgical operations, during childbirth, doctors always have donor blood in stock. Their timely use allows you to control this vitally important parameter for patients - the amount of blood in the body.