Chemical elements in human blood. Blood, its composition and functions

In sports practice, a blood test is used to assess the impact on the athlete's body of training and competitive loads, to assess the functional state of the athlete and his health. The information obtained from the blood test helps the coach to manage the training process. Therefore, a specialist in the field of physical culture must have the necessary understanding of the chemical composition of the blood and its changes under the influence of various physical loads.

General characteristics of blood

The volume of blood in a person is about 5 liters, which is approximately 1/13 of the volume or weight of the body.

By its structure, blood is a liquid tissue and, like any tissue, it consists of cells and intercellular fluid.

Blood cells are called shaped elements . These include red cells (erythrocytes), white cells (leukocytes) and blood plates (platelets). Cells account for about 45% of the blood volume.

The liquid part of the blood is called plasma . The plasma volume is approximately 55% of the blood volume. Plasma from which the protein fibrinogen has been removed is called serum .

Biological functions of blood

The main functions of the blood are as follows:

1. transport function . This function is due to the fact that the blood constantly moves through the blood vessels and carries the substances dissolved in it. There are three types of this function.

Trophic function. Substances necessary for their metabolism are delivered with blood to all organs. (sources of energy, building material for syntheses, vitamins, salts, etc.).

Respiratory function. Blood is involved in the transport of oxygen from the lungs to the tissues and the transport of carbon dioxide from the tissues to the lungs.

Excretory function (excretory). With the help of blood, the end products of metabolism are transported from tissue cells to the excretory organs, followed by their removal from the body.

2. Protective function . This function, first of all, consists in providing immunity - protecting the body from foreign molecules and cells. The ability of blood to coagulate can also be attributed to the protective function. In this case, the body is protected from blood loss.

3. Regulatory function . Blood is involved in maintaining a constant body temperature, in maintaining a constant pH and osmotic pressure. With the help of blood, the transfer of hormones - the regulators of metabolism.

All of these functions are aimed at maintaining the constancy of the conditions of the internal environment of the body - homeostasis (permanence chemical composition, acidity, osmotic pressure, temperature, etc. in body cells).

The chemical composition of blood plasma.

The chemical composition of blood plasma at rest is relatively constant. The main constituents of plasma are as follows:

Proteins - 6-8%

Other organic

substances - about 2%

Minerals - about 1%

Plasma proteins divided into two factions: albumins And globulins . The ratio between albumins and globulins is called the "albumin-globulin coefficient" and is equal to 1.5 - 2. Physical activity is accompanied at first by an increase in this coefficient, and with very long work it decreases.

Albumins- low molecular weight proteins with a molecular weight of about 70 thousand Da. They perform two main functions.

Firstly, due to their good solubility in water, these proteins perform a transport function, carrying various water-insoluble substances with the bloodstream. (for example, fats, fatty acids, some hormones, etc.).

Secondly, due to the high hydrophilicity, albumins have a significant hydration (water) membrane and therefore retain water in the bloodstream. Water retention in the bloodstream is necessary due to the fact that the water content in blood plasma higher than in the surrounding tissues, and water, due to diffusion, tends to exit the blood vessels into the tissues. Therefore, with a significant decrease in albumin in the blood (during starvation, loss of protein in the urine in kidney disease) swelling occurs.

Globulins- These are high-molecular proteins with a molecular weight of about 300 thousand Da. Like albumins, globulins also perform a transport function and contribute to water retention in the bloodstream, but in this they are significantly inferior to albumins. However, globulins

There are also very important functions. So, some globulins are enzymes and accelerate chemical reactions that take place directly in the bloodstream. Another function of globulins is their participation in blood coagulation and in providing immunity. (protective function).

Most plasma proteins are synthesized in the liver.

Other organic matter (except proteins) are usually divided into two groups: nitrogenous And nitrogen-free .

Nitrogen compounds are intermediate and final products of protein and nucleic acid metabolism. Of the intermediate products of protein metabolism in blood plasma, there are low molecular weight peptides , amino acids , creatine . The end products of protein metabolism are primarily urea (its concentration in blood plasma is quite high - 3.3-6.6 mmol / l), bilirubin (end product of heme breakdown) And creatinine (the end product of the breakdown of creatine phosphate).

From the intermediate products of nucleic acid metabolism in blood plasma, one can detect nucleotides , nucleosides , nitrogenous bases . The end product of nucleic acid breakdown is uric acid , which in a small concentration is always found in the blood.

To assess the content of non-protein nitrogenous compounds in the blood, the indicator is often used « non-protein nitrogen » . Non-protein nitrogen includes nitrogen of low molecular weight (non-protein) compounds, mainly those listed above, which remain in plasma or serum after removal of proteins. Therefore, this indicator is also called "residual nitrogen". An increase in residual nitrogen in the blood is observed with kidney diseases, as well as with prolonged muscular work.

For nitrogen-free substances blood plasma are carbohydrates And lipids , as well as intermediate products of their metabolism.

The major carbohydrate in plasma is glucose . Its concentration in a healthy person at rest and on an empty stomach fluctuates in a narrow range from 3.9 to 6.1 mmol / l (or 70-110 mg%). Glucose enters the blood as a result of absorption from the intestine during the digestion of dietary carbohydrates, as well as during the mobilization of liver glycogen. In addition to glucose, plasma also contains small amounts of other monosaccharides - fructose , galactose, ribose , deoxyribose and others. Intermediate products of carbohydrate metabolism in plasma are presented pyruvic And dairy acids. At rest lactic acid (lactate) low - 1-2 mmol / l. Under the influence of physical activity and especially intense, the concentration of lactate in the blood increases sharply. (even dozens of times!).

Lipids are present in blood plasma fat , fatty acids , phospholipids And cholesterol . Due to insolubility in water, all

lipids are associated with plasma proteins: fatty acids with albumins, fat, phospholipids and cholesterol with globulins. Of the intermediate products of fat metabolism in plasma, there are always ketone bodies .

Minerals found in plasma as cations (Na + , K + , Ca 2+ , Mg 2+ etc.) and anions (Сl - , HCO 3 - , H 2 PO 4 - , HPO 4 2- , SO 4 2_ , J - etc.). Most of all, plasma contains sodium, potassium, chlorides, bicarbonates. Deviations in the mineral composition of blood plasma can be observed in various diseases and with significant water loss due to sweating during physical work.

Table 6 The main components of blood

red cells (erythrocytes))

Erythrocytes make up the bulk of blood cells. In 1 mm 3 (µl) blood usually contains 4-5 million red cells. Red blood cells are formed in the red bone marrow, function in the bloodstream and are destroyed mainly in the spleen and liver. Life cycle of these cells is 110-120 days.

Erythrocytes are biconcave cells lacking nuclei, ribosomes, and mitochondria. In this regard, processes such as protein synthesis and tissue respiration do not occur in them. The main source of energy for erythrocytes is the anaerobic breakdown of glucose. (glycolysis).

Protein is the main component of red cells. hemoglobin . It accounts for 30% of the erythrocyte mass or 90% of the dry residue of these cells.

The main function of red blood cells – respiratory . With the participation of erythrocytes, the transfer is carried out oxygen from lungs to tissues and carbon dioxide from tissues to lungs.

In the capillaries of the lungs, the partial pressure of oxygen is about 100 mm Hg. Art. (partial pressure is the part of the total pressure of a mixture of gases that falls on a separate gas from this mixture. For example, at an atmospheric pressure of 760 mm Hg, oxygen accounts for 152 mm Hg, i.e. 1/5 part, so as air usually contains 20% oxygen). At this pressure, almost all hemoglobin binds to oxygen:

Hb + O 2 ¾® HbO 2

Hemoglobin Oxyhemoglobin

Oxygen is added directly to the iron atom, which is part of the heme, and only divalent oxygen can interact with oxygen. (restored) iron. Therefore, various oxidizers (e.g. nitrates, nitrites, etc.), converting iron from divalent to trivalent (oxidized), violate respiratory function blood.

The resulting complex of hemoglobin with oxygen - oxyhemoglobin transported in the bloodstream to various organs. Due to the consumption of oxygen by tissues, its partial pressure here is much less than in the lungs. At low partial pressure, oxyhemoglobin dissociates:

HbO 2 ¾® Hb + O 2

The degree of decomposition of oxyhemoglobin depends on the value of the partial pressure of oxygen: the lower the partial pressure, the more oxygen is split off from oxyhemoglobin. For example, in muscles at rest, the partial pressure of oxygen is approximately 45 mm Hg. Art. At this pressure, only about 25% of oxyhemo-

globin. When working at moderate power, the partial pressure of oxygen in the muscles is approximately 35 mm Hg. Art. and about 50% of oxyhemoglobin is already degraded. When performing intense loads, the partial pressure of oxygen in the muscles decreases to 15-20 mm Hg. Art., which causes a deeper dissociation of oxyhemoglobin (by 75% or more). This nature of the dependence of the dissociation of oxyhemoglobin on the partial pressure of oxygen can significantly increase the supply of oxygen to the muscles during physical work.

An increase in the dissociation of oxyhemoglobin is also observed with an increase in body temperature and an increase in blood acidity. (for example, when large amounts of lactic acid enter the blood during intense muscular work), which also contributes to a better supply of tissues with oxygen.

In general, a person who does not perform physical work uses 400-500 liters of oxygen per day. With high motor activity, oxygen consumption increases significantly.

Transport by blood carbon dioxide is carried out from the tissues of all organs, where it is formed in the process of catabolism, to the lungs, from which it is released into the external environment.

Most of the carbon dioxide is carried in the blood in the form of salts - bicarbonates potassium and sodium. The conversion of CO 2 to bicarbonates occurs in erythrocytes with the participation of hemoglobin. Potassium bicarbonate accumulates in erythrocytes (KHCO 3), and in blood plasma - sodium bicarbonate (NaHCO3). With the blood flow, the formed bicarbonates enter the lungs and turn there again into carbon dioxide, which is removed from the lungs with

exhaled air. This transformation also occurs in erythrocytes, but with the participation of oxyhemoglobin, which occurs in the capillaries of the lungs due to the addition of oxygen to hemoglobin. (see above).

The biological meaning of this mechanism of carbon dioxide transport by blood is that potassium and sodium bicarbonates are highly soluble in water, and therefore they can be found in erythrocytes and plasma in much larger quantities compared to carbon dioxide.

A small part of CO 2 can be carried in the blood in a physically dissolved form, as well as in a complex with hemoglobin, called carbhemoglobin .

At rest, 350-450 l of CO 2 is formed and excreted from the body per day. Performing physical activity leads to an increase in the formation and release of carbon dioxide.

white cells(leukocytes)

Unlike red cells, leukocytes are full-fledged cells with a large nucleus and mitochondria, and therefore such important biochemical processes as protein synthesis and tissue respiration take place in them.

At rest in a healthy person, 1 mm 3 of blood contains 6-8 thousand leukocytes. In diseases, the number of white cells in the blood can both decrease (leukopenia), and increase (leukocytosis). Leukocytosis can also be observed in healthy people, for example, after eating or during muscle work. (myogenic leukocytosis). With myogenic leukocytosis, the number of leukocytes in the blood can increase to 15-20 thousand / mm 3 or more.

There are three types of leukocytes: lymphocytes (25-26 %), monocytes (6-7%) and granulocytes (67-70 %).

Lymphocytes are produced in the lymph nodes and spleen, while monocytes and granulocytes are produced in the red bone marrow.

Leukocytes perform protective function, participating in providing immunity .

In the very general view Immunity is the protection of the body from everything “alien”. By "foreign" we mean various foreign high-molecular substances that have specificity and uniqueness of their structure and, as a result, differ from the body's own molecules.

Currently, there are two forms of immunity: specific And nonspecific . Specific usually refers to the actual immunity, and non-specific immunity - these are various factors of non-specific defense of the body.

The specific immune system includes thymus (thymus), spleen, The lymph nodes, lymphoid accumulations (in the nasopharynx, tonsils, appendix, etc.) And lymphocytes . This system is based on lymphocytes.

Any foreign substance to which it is capable of reacting the immune system organism, denoted by the term antigen . All “foreign” proteins, nucleic acids, many polysaccharides and complex lipids. Antigens can also be bacterial toxins and whole cells of microorganisms, or rather the macromolecules that make up them. In addition, low molecular weight compounds, such as steroids, some drugs, can also exhibit antigenic activity, provided they are previously bound to a carrier protein, for example, blood plasma albumin. (This is the basis for the detection by the immunochemical method of some doping drugs during doping control).

The antigen that enters the bloodstream is recognized by special leukocytes - T-lymphocytes, which then stimulate the transformation of another type of leukocyte - B-lymphocytes into plasma cells, which then synthesize special proteins in the spleen, lymph nodes and bone marrow - antibodies or immunoglobulins . The larger the antigen molecule, the more various antibodies are formed in response to its entry into the body. Each antibody has two binding sites for interaction with a strictly defined antigen. Thus, each antigen causes the synthesis of strictly specific antibodies.

The resulting antibodies enter the blood plasma and bind there to the antigen molecule. The interaction of antibodies with the antigen is carried out by the formation of non-covalent bonds between them. This interaction is analogous to the formation of an enzyme-substrate complex during enzymatic catalysis, with the antibody binding site corresponding to the active site of the enzyme. Since most antigens are macromolecular compounds, many antibodies simultaneously attach to the antigen.

The resulting complex antigen-antibody further exposed phagocytosis . If the antigen is a foreign cell, then the antigen-antibody complex is exposed to plasma enzymes under the general name complement system . This complex enzymatic system ultimately causes the lysis of the foreign cell, i.e. its destruction. The formed lysis products are further exposed to phagocytosis .

Since antibodies are formed in excess in response to antigen intake, a significant part of them remain for a long time in the blood plasma, in the g-globulin fraction. In a healthy person, the blood contains a huge amount of various antibodies formed as a result of contact with many foreign substances and microorganisms. The presence of ready-made antibodies in the blood allows the body to quickly neutralize the antigens that enter the blood again. Prophylactic vaccinations are based on this phenomenon.

Other forms of leukocytes - monocytes And granulocytes participate in phagocytosis . Phagocytosis can be considered as a nonspecific defensive reaction aimed primarily at the destruction of microorganisms entering the body. In the process of phagocytosis, monocytes and granulocytes engulf bacteria as well as large foreign molecules and destroy them with their lysosomal enzymes. Phagocytosis is also accompanied by the formation of reactive oxygen species, the so-called free radicals oxygen, which, by oxidizing the lipoids of bacterial membranes, contribute to the destruction of microorganisms.

As noted above, antigen-antibody complexes also undergo phagocytosis.

Nonspecific defense factors include skin and mucosal barriers, bactericidal activity of gastric juice, inflammation, enzymes (lysozyme, proteinases, peroxidases), antiviral protein - interferon, etc.

Regular sports and health-improving physical education stimulate the immune system and non-specific defense factors and thereby increase the body's resistance to the action of adverse environmental factors, help reduce general and infectious morbidity, and increase life expectancy.

However, the exceptionally high physical and emotional overloads inherent in the sport of the highest achievements have an adverse effect on the immune system. Often, highly qualified athletes have an increased incidence, especially during important competitions. (It is at this time that physical and emotional stress reaches its limit!). Excessive loads for a growing organism are very dangerous. Numerous data indicate that the immune system of children and adolescents is more sensitive to such loads.

In this regard, the most important medical and biological task of modern sports is the correction of immunological disorders in highly qualified athletes through the use of various immunostimulating agents.

blood platelets(platelets).

Platelets are non-nuclear cells formed from the cytoplasm of megakaryocytes - bone marrow cells. The number of platelets in the blood is usually 200-400 thousand/mm 3 . The main biological function of these formed elements is participation in the process blood clotting .

blood clotting- the most complex enzymatic process leading to the formation of a blood clot - blood clot in order to prevent blood loss in case of damage to blood vessels.

Blood coagulation involves components of platelets, components of blood plasma, as well as substances entering the bloodstream from surrounding tissues. All substances involved in this process are called clotting factors . By structure, all clotting factors except two (Ca 2+ ions and phospholipids) are proteins and are synthesized in the liver, and vitamin K is involved in the synthesis of a number of factors.

Protein clotting factors enter the bloodstream and circulate in it in an inactive form - in the form of proenzymes (enzyme precursors), which, if a blood vessel is damaged, can become active enzymes and participate in the process of blood coagulation. Due to the constant presence of proenzymes, the blood is always in a state of "readiness" for clotting.

In the most simplified form, the process of blood coagulation can be divided into three major stages.

At the first stage, which begins with a violation of the integrity of the blood vessel, platelets very quickly (within seconds) accumulate at the site of injury and, sticking together, form a kind of "plug" that limits bleeding. Part of the platelets is destroyed, and from them into the blood plasma phospholipids (one of the coagulation factors). Simultaneously in plasma due to contact with the damaged surface of the vessel wall or with any foreign body (e.g. needle, glass, knife blade, etc.) another clotting factor is activated - contact factor . Further, with the participation of these factors, as well as some other participants in coagulation, an active enzyme complex is formed, called prothrombinase or thrombokinase. This mechanism of activation of prothrombinase is called internal, since all participants in this process are contained in the blood. Active prothrombinase is also formed by an external mechanism. In this case, the participation of a coagulation factor that is absent in the blood itself is required. This factor is present in the tissues surrounding the blood vessels, and enters the bloodstream only when the vascular wall is damaged. The presence of two independent mechanisms of prothrombinase activation increases the reliability of the blood coagulation system.

At the second stage, under the influence of active prothrombinase, the plasma protein is converted prothrombin (this is also a clotting factor) into an active enzyme thrombin .

The third stage begins with the effect of the formed thrombin on the plasma protein - fibrinogen . A part of the molecule is cleaved off from fibrinogen and fibrinogen is converted into a simpler protein - fibrin monomer , whose molecules spontaneously, very quickly, without the participation of any enzymes, undergo polymerization with the formation of long chains, called fibrin-polymer . The resulting fibrin-polymer strands are the basis of a blood clot - a thrombus. First, a gelatinous clot is formed, which includes, in addition to fibrin-polymer filaments, plasma and blood cells. Further, special contractile proteins are released from the platelets included in this clot. (type of muscle), causing contraction (retraction) blood clot.

As a result of these steps, a strong thrombus is formed, consisting of fibrin-polymer filaments and blood cells. This thrombus is located in the damaged area of ​​the vascular wall and prevents bleeding.

All stages of blood coagulation proceed with the participation of calcium ions.

In general, the process of blood clotting takes 4-5 minutes.

Within a few days after the formation of a blood clot, after the restoration of the integrity of the vascular wall, the now unnecessary thrombus is resorbed. This process is called fibrinolysis and is carried out by splitting fibrin, which is part of the blood clot, under the action of the enzyme plasmin (fibrinolysin). This enzyme is formed in the blood plasma from its predecessor, the plasminogen proenzyme, under the influence of activators that are in the plasma or enter the bloodstream from the surrounding tissues. Plasmin activation is also facilitated by the appearance of fibrin-polymer during blood clotting.

Recently, it has been found that there is still in the blood anticoagulant a system that limits the clotting process to only the damaged area of ​​the bloodstream and does not allow total clotting of all blood. The formation of the anticoagulant system involves the substances of plasma, platelets and surrounding tissues, which have the common name anticoagulants. According to the mechanism of action, most anticoagulants are specific inhibitors that act on coagulation factors. The most active anticoagulants are antithrombins, which prevent the conversion of fibrinogen into fibrin. The most studied thrombin inhibitor is heparin , which prevents blood clotting both in vivo and in vitro.

The fibrinolysis system can also be attributed to the anticoagulant system.

Acid-base balance of the blood

At rest, in a healthy person, the blood has a weakly alkaline reaction: pH of capillary blood (it is usually taken from the finger of the hand) is approximately 7.4, the pH of venous blood is 7.36. The lower value of the pH value of venous blood is explained by the higher content of carbon dioxide in it, which occurs in the process of metabolism.

The constancy of blood pH is provided by the buffer systems in the blood. The main blood buffers are: bicarbonate (H 2 CO 3 /NaHCO 3), phosphate (NaH 2 PO 4 /Na 2 HPO 4), proteinaceous And hemoglobin . Hemoglobin turned out to be the most powerful buffer system of blood: it accounts for 3/4 of the entire buffer capacity of blood. (see the mechanism of buffer action in the course of chemistry).

In all buffer systems of the blood, the main (alkaline) component, as a result of which they neutralize much better acids entering the bloodstream than alkalis. This feature of blood buffers is of great biological importance, since various acids are often formed as intermediate and final products during metabolism. (pyruvic and lactic acids - during the breakdown of carbohydrates; metabolites of the Krebs cycle and b-oxidation of fatty acids; ketone bodies, carbonic acid, etc.). All the acids that arise in the cells can enter the bloodstream and cause a pH shift to the acid side. The presence of a large buffer capacity in relation to acids in blood buffers allows them to neutralize significant amounts of acidic products entering the blood, and thereby help maintain a constant level of acidity.

The total blood content of the main components of all buffer systems is denoted by the term « Alkaline blood reserve ». Most often, the alkaline reserve is calculated by measuring the ability of the blood to bind CO 2 . Normally, in humans, its value is 50-65 vol. % , i.e. every 100 ml of blood can bind 50 to 65 ml of carbon dioxide.

Excretory organs are also involved in maintaining a constant blood pH. (kidneys, lungs, skin, intestines). These organs remove excess acids and bases from the blood.

Due to buffer systems and excretory organs, fluctuations in pH under physiological conditions are insignificant and not dangerous for the body.

However, with metabolic disorders (for diseases, when performing intense muscle loads) the formation of acidic or alkaline substances in the body can sharply increase (first of all, sour ones!). In these cases, blood buffer systems and excretory organs are not able to prevent their accumulation in the bloodstream and keep the pH value at a constant level. Therefore, with excessive formation of various acids in the body, the acidity of the blood increases, and the value of the hydrogen index decreases. This phenomenon is called acidosis . With acidosis, blood pH can decrease to 7.0 - 6.8 units. (It should be remembered that a shift in pH by one unit corresponds to a change in acidity by 10 times). Reducing the pH value below 6.8 is incompatible with life.

Accumulation of alkaline compounds in the blood can occur much less frequently, while the pH of the blood increases. This phenomenon is called alkalosis . The limiting increase in pH is 8.0.

Athletes often have acidosis caused by the formation of large amounts of lactic acid in the muscles during intensive work. (lactate).

Chapter 15 BIOCHEMISTRY OF THE KIDNEYS AND URINE

Urine, as well as blood, is often the object of biochemical studies conducted in athletes. According to the analysis of urine, the coach can obtain the necessary information about the functional state of the athlete, about the biochemical changes that occur in the body when performing physical activities of a different nature. Since when taking blood for analysis, infection of the athlete is possible (for example, infection with hepatitis or AIDS), then recently, urine research has become increasingly preferable. Therefore, a trainer or teacher of physical education should have information about the mechanism of urine formation, about its physical and chemical properties and chemical composition, about changes in urine parameters during training and competitive loads.

Blood belongs to the supporting-trophic tissues. It consists of cells - formed elements and intercellular substance - plasma. The formed elements of blood include erythrocytes, leukocytes and platelets. Blood plasma is a liquid. Blood is the only tissue of the body where the intercellular substance is a liquid.

To separate the formed elements from the plasma, the blood must be prevented from clotting and centrifuged. Formed elements, as heavier ones, will settle, and above them there will be a layer of a transparent, slightly opalescent yellow liquid - blood plasma.

If the volume of blood is taken as 100%, then the formed elements make up about 40...45%, and plasma - 55...60%. The volume of formed elements in the blood, mainly erythrocytes, is called hematocrit value or hematocrit. Hematocrit can be expressed as a percentage (40 ... 45%) or in liters of red blood cells in 1 liter of blood (0.40 ... 0.45 l / l).

When the animal has not been watered for a long time or it has lost a lot of fluid (strong sweating, diarrhea, profuse vomiting), the hematocrit value increases. In this case, they talk about "thickening" of the blood. This condition is unfavorable for the body, since the resistance of the blood increases significantly during its movement, which causes the heart to contract more strongly. In order to compensate, water passes from the tissue fluid into the blood, its excretion by the kidneys decreases and, as a result, thirst arises. A decrease in hematocrit often occurs in diseases - with a decrease in the formation of red blood cells, their increased destruction, or after blood loss.

The chemical composition of blood. Blood plasma contains 90...92% water and 8...10% solids. The dry residue consists of proteins, lipids, carbohydrates, intermediate and final products of their metabolism, minerals, hormones, vitamins, enzymes and other biologically active substances. It is important to note that, despite the constant exchange of substances between blood and tissues, the composition of blood plasma does not change significantly. Very narrow limits of fluctuations in the content of total protein, glucose, minerals - electrolytes. Therefore, the most insignificant deviations in their level, which go beyond the physiological boundaries, lead to severe disturbances in the functioning of the body. Other constituent components of blood - lipids, amino acids, enzymes, hormones, etc. - may have a wider range of fluctuations. Blood also contains oxygen and carbon dioxide.

Consider the physiological significance of individual substances contained in the blood.

Squirrels. Blood proteins consist of several fractions, which can be separated in various ways, for example, by electrophoresis. Each fraction contains a large number of proteins with specific functions.

Albumins. Formed in the liver, they have a small molecular weight compared to other proteins. In the body, they perform a trophic, or nutritional, function, being a source of amino acids, and a transport one, participating in the transfer and binding of fatty acids, bile pigments, and some cations in the blood.

Globulins. They are synthesized in the liver, as well as by various cells - leukocytes, plasma cells. The molecular weight of globulins is greater than that of albumins. The globulin fraction of proteins can be further divided into three groups - alpha, beta and gamma globulins. Alpha and beta globulins are involved in the transport of cholesterol, phospholipids, steroid hormones, and cations. The gamma globulin fraction includes various antibodies.

The ratio of albumin to globulin is called the protein ratio. In horses and cattle, there are more globulins than albumins, and in pigs, sheep, goats, dogs, rabbits, and humans, albumins predominate. This feature affects some of the physicochemical properties of blood.

Proteins play a big role in blood clotting. Thus, fibrinogen, which belongs to the globulin fraction, during clotting passes into an insoluble form - fibrin and becomes the basis of a blood clot (thrombus). Proteins can form complexes with carbohydrates (glycoproteins) and with lipids (lipoproteins).

Regardless of the function of each protein, and there are up to 100 of them in blood plasma, they together determine the viscosity of the blood, create a certain colloidal pressure in it, and participate in maintaining a constant blood pH.

Physiological fluctuations in the amount of total blood protein are associated with age, sex, productivity of animals, as well as with the conditions of their feeding and maintenance. So, in newborn animals there are no gamma globulins (natural antibodies) in the blood, they enter the body with the first portions of colostrum. With age, the content of globulins in the blood increases and at the same time the level of albumins decreases. With high milk productivity of cows, the content of proteins in the blood increases. After vaccination of animals, an increase in the content of proteins in the blood occurs due to immunoglobulins. In healthy animals, the total amount of protein in the blood is 60...80 g/l, or 6...8 g/100 ml.

As you know, a characteristic feature of the chemical composition of proteins is the presence of nitrogen, so many methods for determining

measurements of the amount of proteins in the blood and tissues are based on the determination of the concentration of protein nitrogen. However, nitrogen is also present in many other organic substances that are products of protein breakdown - these are amino acids, uric acid, urea, creatine, indican, and many others. The total nitrogen of all these substances (with the exception of protein nitrogen) is called residual, or non-protein, nitrogen. Its amount in plasma is 0.2 ... 0.4 g / l. Residual nitrogen in the blood is determined in order to assess the state of protein metabolism: with increased protein breakdown in the body, the content of residual nitrogen increases.

L and p and d s. Blood lipids are divided into neutral lipids, consisting of glycerol and fatty acids (mono-, di- and triglycerides), and complex - cholesterol, its derivatives and phospholipids. There are also free fatty acids in the blood. The content of total lipids in the blood can vary widely (for example, in cows, lipid fluctuations are normal within 1 ... 10 g / l). With an increase in the content of lipids in the blood (for example, after eating a fatty meal), the plasma begins to noticeably opalescent, becomes cloudy, acquires a milky hue, and in chickens, when the plasma is settled, fat can float up in the form of a thick drop.

Carbohydrates. Blood carbohydrates are represented mainly by glucose. But the glucose content is determined not in plasma, but in whole blood, since glucose is partially adsorbed on erythrocytes. The concentration of glucose in the blood in mammals is kept within very narrow limits: in animals with a single-chamber stomach 0.8..L.2 g/l, and with a multi-chamber stomach 0.04...0.06 g/l. In birds, the content of glucose in the blood is higher, which is explained by the peculiarities of the hormonal regulation of carbohydrate metabolism.

In addition to glucose, blood plasma also contains some other carbohydrates - glycogen, fructose, as well as products of intermediate metabolism of carbohydrates and lipids - lactic, pyruvic, acetic and other acids, ketone bodies. There are more volatile fatty acids (VFA) in the blood of ruminants than in animals of other species, this is due to the peculiarities of cicatricial digestion. The blood cells contain a small amount of glycogen.

As already mentioned, the blood contains various biologically active substances - enzymes, hormones, mediators, etc.

The mineral composition of the blood. Inorganic substances in the blood can be both in a free state, i.e., in the form of anions and cations, and in a bound state, entering the structure of organic substances. Most of all in the blood there are sodium, potassium, calcium, magnesium cations, chloride anions, bicarbonates, phosphates, the OH hydroxyl group. The blood also contains iodine, iron, copper, cobalt, manganese and other macro- and microelements. The total content of minerals in blood constant value (up to 10 g/l) for each type of animal.

It should be borne in mind that the concentration of individual ions in the blood plasma and in the formed elements is not the same. So, mainly in the plasma are sodium, calcium, chlorine, bicarbonates, while in erythrocytes there is a higher concentration of potassium, magnesium and iron. However, in erythrocytes, and in leukocytes, and in blood plasma, the level of concentration of individual ions (ionogram) is constant, which is maintained by continuous active and passive transport of ions through semipermeable cell membranes.

Physiological fluctuations in the content of mineral substances in the blood are due to nutrition, age, productivity of animals and their physiological state. Blood properties such as density, pH, osmotic pressure depend on their content.

Protecting the body from pathogenic microbes

If a person weighs 65 kg, he has 5.2 kg of blood (7-8%); Of 5 liters of blood, about 2.5 liters are water.

The composition of plasma (it accounts for 55%) includes minerals (salts of sodium, calcium, and many others) and organic (proteins, glucose, and others). Plasma takes part in the transport of substances and blood coagulation.

Figure 1.5.7. Dynamic balance of blood coagulation and fibrinolysis systems:

1 - wall of a blood vessel; 2 - damage to the vessel wall; 3 - platelets; 4 - adhesion and aggregation of platelets; 5 - thrombus; 6 - coagulation system factors

As can be seen in this figure, blood coagulation is based on the conversion of soluble plasma protein fibrinogen into dense protein fibrin . Among the agents of the process are calcium ions and prothrombin. If a small amount of sodium oxalate or citrate (sodium citrate) is added to fresh blood, then clotting will not occur, since these compounds bind calcium ions so strongly. This is used when storing donated blood. Another substance that is required for the normal course of the blood coagulation process is the previously mentioned prothrombin. This plasma protein is produced in the liver, and vitamin K is necessary for its formation. The components listed above (fibrinogen, calcium ions and prothrombin) are always present in the blood plasma, but under normal conditions, the blood does not coagulate.

The fact is that the process cannot start without one more component - thromboplastin - an enzymatic protein contained in platelets and in the cells of all tissues of the body. If you cut your finger, thromboplastin is released from the damaged cells. Thromboplastin is also secreted from platelets that are destroyed during bleeding. When interacting in the presence of calcium ions, thromboplastin with prothrombin, the latter is cleaved and forms an enzyme thrombin , which converts soluble protein fibrinogen into insoluble fibrin . Platelets play an important role in the mechanism of stopping bleeding. As long as the vessels are not damaged, platelets do not stick to the walls of the vessels, but if their integrity is violated or pathological roughness (for example, an atherosclerotic plaque) appears, they settle on the damaged surface, stick together with each other and release substances that stimulate blood coagulation. This is how a blood clot is formed, which, when growing, turns into a blood clot.

The process of thrombus formation is a complex chain of interactions of various factors and consists of several stages. At the first stage, the formation of tomboplastin occurs. A number of plasma and platelet coagulation factors take part in this phase. In the second phase, thromboplastin in combination with coagulation factors VII and X and in the presence of calcium ions convert the inactive prothrombin protein into the active thrombin enzyme. In the third phase, the soluble protein fibrinogen (under the action of thrombin) is converted into insoluble fibrin. Fibrin threads, woven into a dense network, with captured platelets form a clot - a thrombus - covering the defect of the blood vessel.

The liquid state of the blood under normal conditions maintains an anticoagulant - antithrombin . It is produced in the liver and its role is to neutralize small amounts of thrombin that appear in the blood. If, nevertheless, the formation of a blood clot has occurred, then the process of thrombolysis or fibrinolysis begins, as a result of which the thrombus gradually dissolves and the patency of the vessel is restored. If you look again at figure 1.5.7, or rather, on its right side, you can see that the destruction of fibrin occurs under the action of the enzyme plasmin . This enzyme is formed from its precursor plasminogen under the influence of certain factors called plasminogen activators .

The tissue of the body, consisting of plasma and shaped elements suspended in it - erythrocytes, leukocytes and platelets. Carries out the transport of gases and substances in the body, and also performs protective, regulatory and some other functions.

Human blood makes up approximately 8% of the total body weight. This is a special connective tissue, a vital biological fluid.

Blood constantly circulates through our body and life is simply impossible without this movement. It penetrates into all organs and tissues and can change the composition depending on the state of the body. That is why one blood test can often provide information about previous and existing diseases, general condition organism and disturbances in different organs.

How to properly understand the results? What is blood made of and why are its components important? What are blood types, how do they differ, and why is it important to know them when transfusing? You will find answers to these and many other questions in this article.

blood in adults

The volume of blood in the human body is from 4 to 6 liters. It is a multicomponent connective tissue, consisting mainly of specific cells and liquid plasma. The ratio of elements is conditionally stable and may vary depending on age, health status, previous infections and other factors.

Blood performs several important functions in the body:

• Transport of substances.

Thanks to the movement of blood, the organs receive the necessary nutrients and get rid of metabolic products. In particular, it is the blood that supplies oxygen to all parts of the body. Supply and cleaning occur continuously, and the suspension of this process, for example, when the vessel is blocked for only 10-15 minutes, can lead to irreversible consequences for the starving tissue - the development of necrosis.

• Homeostasis (maintaining a constant internal environment in the body).

Human blood is responsible for life support and tissue regeneration, water and electrolyte balance. It also controls body temperature.

• Immunity.

It is in the blood that protective cells (leukocytes) and antibodies to various antigens are located. Without this fabric, we would not be able to fight various types pathogenic microorganisms.

• Turgor.

Due to the constant flow of blood, the organs retain their shape and tissue tension.

Blood in men

Men have more blood volume than women - up to 6 liters. At the same time, it has a higher concentration of red blood cells, and hence hemoglobin (135-160g / l), which is responsible for oxygen transport. This is extremely important for the endurance of the body, because during physical exertion, the need for this gas in organs and tissues increases. The peculiarity of male blood allows it to be delivered faster, which means that it is possible to withstand the load longer.

The erythrocyte sedimentation rate in male blood is lower - up to 10 mm / h. In women, this figure can reach up to 15 mm / h, which in the male analysis will indicate the development of the inflammatory process. Also, unlike the blood of women, men's blood is relatively constant in composition throughout life.

Women's blood

Volume common blood in female body less - 4-5 liters, and it can vary in composition. This is most clearly reflected in the rate of hemoglobin, which can significantly decrease during menstruation or pregnancy. On average, the blood of women contains 120-140 g / l, however, representatives of the weaker sex can tolerate lower rates. For example, anemia up to 90 g/l can be manifested only by slight fatigue.

Pregnancy significantly affects a woman's blood counts. First of all, the level of hormones - estrogen, progesterone, prolactin - rises. The volume of circulating blood also changes, because the circulatory system of the growing fetus is connected to the mother's body. An increase in volume affects blood saturation: for example, the amount of protein in plasma decreases, the level of hemoglobin and creatinine drops.

But other indicators in the general blood test may increase:

• The level of insulin often exceeds the norm, doctors even singled out a separate diagnosis - diabetes in pregnant women. This condition is temporary and disappears after childbirth.
• Since metabolic processes are noticeably accelerated in the body of a pregnant woman, the blood of women is saturated with cholesterol. Its level during this period, as a rule, is more than normal.
• An increased concentration of uric acid can be an indicator of a malfunction in the kidneys, even intoxication.
• A slight excess of potassium, chlorine, phosphorus and sodium is observed in healthy pregnant women and is not a dangerous symptom.

Another feature of the blood of women during pregnancy is a significant increase in clotting. This is a natural process of preparing the body for an increase in blood levels and a certain protection against possible blood loss during childbirth.

Anemia in pregnancy

The body of a pregnant woman needs an increased intake of iron, so one of the most common diagnoses during this period is iron deficiency anemia. Most often, it manifests itself in the second half of pregnancy, but with a weakened body or low weight, anemia can be observed from the first weeks.

Anemia is diagnosed when the hemoglobin level in the blood falls below 110 g/l. Tissues and organs receive less oxygen, which is transported by hemoglobin, and the woman feels general weakness, fatigue, dizziness and headaches, shortness of breath appears. But the most dangerous in anemia of pregnant women is oxygen starvation of the fetus, which affects growth and development, in severe cases it can provoke a miscarriage or placental abruption.

Blood in breastfeeding women

The milk of a nursing woman is produced from the content of blood plasma. Therefore, its composition can affect milk. So, in particular, certain types of drugs can be transferred to the baby. Wherein breast-feeding safe for diseases that are transmitted through the blood: B and C, HIV. Therefore, when positive tests blood for these infections, breastfeeding can usually continue.

The composition of the blood in children is notable for its instability - in the process of growth, the ratio of the main components is constantly changing. In addition, the indicators are highly dependent on external factors: diet, daily routine, physical activity. The level of leukocytes in children's blood is increased, since it is during this period that immunity is actively formed - blood cells constantly encounter new antigens, antibodies are produced. After birth and before adolescence, the blood in children gradually comes to the indicators of an adult: clotting improves, the erythrocyte sedimentation rate increases, and the total number of formed elements returns to normal.

Blood in newborns

In percentage terms, the amount of blood in a newborn is much higher than in an adult - it is about 14% of body weight, it turns out that about 150 ml per 1 kg of weight. In the first 12 hours, the blood in children is characterized by an increased level of immature erythrocytes and hemoglobin. However, already in the first day, these figures fall significantly. The fact is that red blood cells in the blood of newborns live much less than in an adult body - they are destroyed on average in 12 days.

Anemia is common in premature babies in the first months of life. If, with such a decrease in hemoglobin, the general state of health does not cause concern, additional symptoms do not appear, then early anemia of prematurity is not considered dangerous and is a common reaction to adaptation to new conditions.

After the birth of a child, up to 150 ml of blood with specific characteristics is stored in the placenta and umbilical vein. Previously, it was not given much importance, but today, cord blood is increasingly being preserved. It contains a large number of stem cells that can be used in the treatment various diseases. They are unique in their characteristics, because they are not differentiated, they can give rise to any specialized cell types.

The circulatory system consists of the heart, which pumps blood, and the hollow vessels through which it flows. In the human body, blood moves in two circles:

• Small passes only through the heart and lungs. Here the blood is enriched with oxygen and gives off carbon dioxide - that is why we exhale it.
• big circle It starts in the heart and travels through all other tissues and organs. In this circle, blood provides the transportation of nutrients to all parts of the body.

Vessels are hollow tubes of different diameters through which blood flows continuously and under pressure.

Blood from an artery

Arteries are blood vessels that carry blood from the heart muscle to various organs. This is oxygenated blood, purified from metabolic products, which delivers the necessary substances. In a small circle, arterial blood, on the contrary, flows through the veins to the heart.

The arteries pulsate in the rhythm of the contractions of the heart - these tremors are well felt if you press the vessel a little with your fingers. Therefore, it is in the arteries that the pulse is measured. Also by the strength of the blood flow in them is determined arterial pressure- one of the key indicators of the cardiovascular system.

Vessels differ in diameter, the largest in the human body is the aorta. The walls of the arteries are quite dense and elastic, able to withstand great pressure. At the same time, it is damage to arteries, especially large ones, that cause rapid blood loss of a large volume, since blood is poured out of the vascular bed under pressure. Arterial blood is bright scarlet in color.

Veins are vessels that carry blood from organs to the heart. It is deprived of oxygen, enriched with carbon dioxide and other metabolic products. The main function of blood from a vein is to transport waste products produced by organs.

The movement of blood through the arteries is provided by the beats of the heart. But it passes through the veins due to venous impulses and moves forward with the help of special venous valves. The pressure here is less than in the arteries, moreover, they need to raise blood from lower extremities, therefore, these are vessels with developed wall musculature. If, for some reason, the vessels are weak, and the valves do not work efficiently enough, varicose veins develop.

Among the largest veins in diameter are the jugular, superior and inferior vena cava. Their damage also leads to serious blood loss.

Blood from a vein is dark, thick, normally warmer than arterial blood. All veins and arteries are connected by capillaries located in the organs - it is through them that the blood gives off oxygen and other nutrients, and also takes in carbon dioxide.

Blood: general characteristics of the components

Human blood is a multicomponent liquid. 40-45% are formed elements: erythrocytes, leukocytes, platelets. The remaining 55-60% is occupied by plasma - the liquid part, consisting mainly of water, through which cells move. The ratio of elements and plasma is called hematocrit. In normal blood in men, it ranges from 0.40-0.48, and in women it is lower - 0.36-0.46.

Each component of the blood performs its functions, its increased or decreased level in the analysis indicates the presence of diseases, can threaten life. Formed elements are produced by the bone marrow, so their lack or defective form may indicate violations of its work.

red blood cells

Erythrocytes are red blood cells that are responsible for transporting oxygen and carbon dioxide. They perform this function due to hemoglobin, an iron-containing protein that can attach oxygen to itself when blood passes through the pulmonary circulation. The cytoplasm of a healthy blood cell is 98% composed of this protein. This is what gives it its characteristic red color.

The lack of red blood cells is the main cause of anemia. However, in some cases, marriage is also found in the cells themselves - with a sufficient number of red blood cells, the hemoglobin content in them is lowered. Such deviations from the norm cause oxygen starvation of organs and tissues, and can lead to other diseases.

Erythrocytes are the most numerous formed elements, they make up about 99% of their total volume, as well as ¼ of all cells in the human body.

In shape, erythrocytes resemble a disc concave in the center. If, for some reason, their shape changes, this also becomes the cause of blood diseases.

• Function: transport of gases.
• Amount per liter of blood: for men - 3.9-5.5 x 1012, for women - 3.9-4.7 x 1012, for newborns - up to 6.0 x 1012.
• Size: diameter - 6.2-8.2 microns, thickness - 2 microns.
• Life time: 100-120 days.

Leukocytes

Leukocytes are white blood cells that vary in size and appearance. Moreover, all of them are colorless and are nuclear cells. There are such types of leukocytes: lymphocytes, basophils, neutrophils, eosinophils and monocytes. Despite the difference in size and types, they all perform the same function - protecting the body from various antigens. These cells are able to penetrate through the capillaries into the tissues of the organs, where they attack foreign microorganisms.

Different types of leukocytes are highly specialized blood cells that appear in specific diseases. Therefore, their presence, type, number in the general blood test can tell the doctor what kind of infection is present in the body and at what stage it is. The onset of the course of the disease and the acute period are characterized by an increased level of young leukocytes; during recovery, on the contrary, eosinophil cells predominate in the blood. At viral infections the number of lymphocytes increases, with bacterial - different types of neutrophils, and with sluggish infections in the blood, the content of monocytes is increased. Deciphering blood by leukocytes also helps to understand how effective the prescribed treatment is.

Leukocytes are able to capture foreign bodies and absorb them, however, in the process of fighting, most white blood cells die. In these places, decay products accumulate - pus is formed.

• Function: phagocytosis - a protective reaction of the body.
• Amount per liter of blood: adults - 4-9x109, children under one year old - 6.5-12.5x109.
• Size: depends on the type of leukocyte.
• Lifetime: 2-4 days, some forms 10-12 days, lymphocytes may remain throughout life.

platelets

Platelets are colorless and non-nucleated cells that are responsible for stopping bleeding in the first stage. One of the main features of these uniform elements is activation from the slightest stimulus. In the normal state, platelets travel along the bloodstream, however, as soon as an impulse arrives, they change and acquire the ability to stick together and stick to the vessel wall. Due to this, they clog even the smallest damage to the walls of blood vessels, do not allow bleeding to occur.

Similar processes occur in the body all the time, however, in some diseases, the formation of blood clots is dangerous. For example, with atherosclerosis - a decrease in the diameter of arteries due to cholesterol deposits on their walls. In this case, a detached blood clot can be carried by the blood flow to another part of the cardiovascular system, and block the diseased artery. This is the most common cause of myocardial infarction.

• Function: blood clotting.
• Quantity per liter of blood: a blood test can normally show from 180 to 400 thousand cells.
• Size: 2-4 microns, able to change the size depending on the need.
• Life time: 5-7 days.

blood plasma

Blood plasma is a liquid medium in which formed elements move. It is 90-92% water and 10% organic and inorganic matter. This ratio of components provides a normal blood flow, but if the amount of water decreases, the rheology also decreases significantly. And this can lead to stagnant processes, an increase in the load on the heart.

10% of blood plasma accounts for:

• Proteins - albumins, globulins and fibrinogen.
• Inorganic salts that are responsible for maintaining the pH level and regulating the amount of water - calcium, chlorine, sodium, potassium, magnesium, and others.
• Other substances - glucose, urea, amino acids, uric acid, vitamins, etc.

Plasma is often used as a separate component in blood transfusions.

Since the condition of the blood can determine the presence of infections, as well as the course of various diseases, there are many specialized tests. For example, blood can be tested for the presence of viruses and antibodies to them. A blood test for tumor markers identifies specific proteins that are produced by malignant cells. Checking the content of hormones can tell about the state of the endocrine system, and for women during pregnancy - about the development of the fetus. Elevated blood sugar is a confirmation of the presence of diabetes.

Almost any health diagnosis begins with basic studies, among which one of the key is a complete blood count. It is according to his indicators that the doctor judges which diagnosis to prescribe next.

General blood analysis

A complete blood count is a study of all formed elements, their quantity and parameters, plasma and hematocrit. Separately, hemoglobin is checked, the leukocyte formula and other important indicators are calculated.

Main researches:

• Hemoglobin and red blood cells are the main parameters for determining anemia.
• The color indicator is how erythrocytes are saturated with hemoglobin. It is necessary to clarify the diagnosis of anemia and the choice of treatment. A blood test will normally be marked in the range from 0.80 to 1.05.
• Leukocytes - an indicator of infection and the presence of immunity to specific species pathogenic microorganisms. The leukocyte formula (leukogram) is calculated, which shows the percentage of different types of white blood cells.
  • Stab (p / I) neutrophils.
  • Segmented (s / I) neutrophils.
  • Eosinophils - may indicate recovery from an infectious disease, as well as allergies or helminthic infestations.
  • Basophils.
  • Lymphocytes are cells responsible for acquired immunity. Their presence suggests that a person has had an infection in the past.
  • Monocytes.
• ESR (erythrocyte sedimentation rate) may indicate the development of an inflammatory process.
• Platelets - a low level indicates a deterioration in blood clotting. In some cases, this is the norm, for example, during menstruation, as well as when taking medications that affect the formation of blood clots.

For analysis, blood is taken from a vein or from a finger.

This is a more complex study that gives an expanded picture of the state of human health. Thanks to biochemical analysis blood, a doctor can judge the functional state of organs and tissues, suspect the development of pathological processes (for example, malignant neoplasms). Also, with its help, the effectiveness of therapy is checked, adjustments are made to the prescribed treatment.

The main indicators of biochemistry:

• Glucose ("blood sugar") - the main parameter for diagnosis diabetes.
• Cholesterol is checked for two types: LDL (low density, LDL), HDL (high density, HDL). An increase in the first is dangerous, since it is an indirect confirmation of the presence of atherosclerosis. When deciphering blood, attention is paid, first of all, to him.
• The coefficient of atherogenicity (Ka) is a calculated indicator of the degree of risk of developing atherosclerosis in humans.
• Urea and creatinine shows the work of the kidneys, an increased figure indicates a violation of filtration.
• Lipids, in particular triglycerides and phospholipids, which are responsible for the structural and energy functions of the body.
• Bilirubin and total protein in the blood speak primarily of liver diseases.
• Amylase and lipase are important in determining the condition of the pancreas. Increased amylase indicates inflammation.
• Albumin is the main plasma protein. Used to refine other indicators.
• The AST enzyme is needed to assess the work of the heart.
• The enzyme ALT shows how the liver works.
• Rheumatoid factor - certain antibodies, the presence of which indicates various autoimmune diseases.
• Alkaline phosphatase is mainly responsible for the condition of the bones. With the help of this indicator of a biochemical blood test, rickets and other diseases can be determined.
• Sodium and chlorine regulates the water and acid-base balance of the blood.
• Calcium and potassium shows the state of the cardiovascular system.

This analysis is extremely important for the diagnosis of general health. Therefore, doctors recommend donating blood for biochemistry at least once a year.

Deciphering a blood test

Blood norms are highly dependent on age and gender. In the form, these indicators are most often indicated in a separate column, however, deciphering the blood test is the task of the doctor alone. Since deviation from the norm can be caused not by health problems, but by the conditions under which the analysis was taken. For example, after physical activity may increase platelet levels. And blood sugar depends on when and what a person ate the day before, whether he was worried during the test, whether he took alcohol. Nicotine can also change performance.

When to donate blood: preparation for analysis

The composition of the blood and the level of some indicators depend on the foods that the person has eaten, so the study is carried out on an empty stomach in the morning. Strictly speaking, from the last meal to the analysis, 8-12 hours should pass.

In addition, a few days before donating blood, you need to exclude alcohol, fried or too fatty foods, and taking medications (for example, aspirin). Do not smoke for at least 1 hour before the examination.

Physical activity can also affect the results, so before donating blood, you need to sit quietly for 10-15 minutes, restore breathing, and before that, minimize possible stress. On the morning of the test, it is better to cancel the morning run and exercise.

Water does not affect blood components, but it can increase the percentage of lymph (?).

For those who donate blood for cholesterol, it is important to cancel drugs that affect this indicator within 2 weeks. They can be taken only if the decoding of the blood test is necessary to verify the effectiveness of the treatment.

Blood transfusion (hemotransfusion) is a complex tissue transplantation operation, therefore it is performed in extreme cases and taking into account all possible risks. To date, clear standards have been developed for the appropriateness of this procedure. After all, complications from incompatibility can lead to serious consequences, even death.

However, blood transfusion is a life-saving treatment for many patients. Some people need a blood transfusion every day.

Donor blood is most often divided into components - red blood cells, plasma, cryoprecipitate and platelet mass. It is their doctors who use them for planned transfusions. This not only reduces the risk of complications, but also makes it possible to use one portion of donated blood for different recipients. Whole blood is also used in blood transfusion, but less frequently.

Reasons for a blood transfusion

One of the main indications for blood transfusion is massive blood loss. It can occur due to injuries, accidents, vascular diseases, as well as during childbirth. Bleeding is dangerous because a decrease in the level of blood in the channel affects homeostasis, organ turgor and the ability of blood to carry oxygen. Often, blood loss is associated precisely with oxygen starvation, which can only be eliminated by transfusion of whole blood or red blood cells.

Hemotransfusion is also prescribed for such diagnoses:

• Anemia of varying severity and etiology.
• Blood coagulation disorders.
• Leukopenia.
• Sepsis.
• body intoxication.
• Chronic and acute purulent processes, for example, in the case of extensive burns.
• Oncological diseases, chemotherapy.

For some infections, liver diseases, DIC, plasma is used.

One more possible reason transfusions are planned operations. If the patient's indicators and blood level are normal, it is possible to carry out the so-called auto-donation - the preparation of one's own blood. This completely eliminates the risk of incompatibility.

Blood rate

Normally, the blood in the body is redistributed into circulating and deposited. The first is approximately 60% of the total volume and moves through the cardiovascular system. It is she who pours out with blood loss. The deposited blood is a certain reserve, 40% of the total amount, which is in the liver, spleen, connective tissues. In critical situations, it can replace the circulating one.

Thus, blood loss up to 20% is not life threatening - blood is redistributed, blood pressure in the bloodstream does not fall. Of course, this condition leads to anemia, but if the hemoglobin does not fall below 80-70 g / l, blood transfusion is not advisable. Saline solutions can be introduced into the bloodstream, and only if the condition does not improve, the red blood cell mass is transfused.

Blood groups I, II, III, IV

IN modern medicine There are several classification systems for blood types, the most popular of which are 0AB (4 blood groups) and the Rh factor. It is on them that doctors are guided in determining the compatibility of the donor and recipient.

Even at the beginning In the 20th century, the Australian immunologist Karl Landsteiner noticed that in some cases, mixing the blood of two patients leads to agglutination of red blood cells, the so-called agglutination. This process is irreversible and leads to death. In the course of research, the doctor discovered that antigens A and B, as well as antibodies to them α and β in plasma, can be found on the surface of red blood cells. The simultaneous presence of an antigen and an antibody to it is impossible, so 4 blood groups were identified:

• Group 1 (0) - only α and β antibodies.
• Group 2 (A) - A and β.
• Group 3 (B) - α and B.
• 4 Group (AB) - only antigens A and B.

These indicators do not change throughout life - the blood type remains constant from birth to death.

Agglutination is caused by the introduction of an antigen to which there is an antibody in the blood. For example, for the 2nd blood group (the presence of β), transfusion of the 3rd group (the presence of B) will lead to complications. Therefore, donors with blood of the 1st group were considered universal, but the owners of AB, on the contrary, were highly specialized. By modern standards, such compatibility rules do not apply, and blood transfusion is allowed only within the same group.

Rh factor

Another important indicator for blood compatibility is protein D, which may or may not be present on the surface of the erythrocyte. It is its presence that determines the Rh factor - positive RH + and negative RH-.

According to the outdated system, Rh-negative donors were considered universal, since their blood was not perceived as foreign in all patients. That is, the blood of group 1 with a negative Rh factor could be transfused to any patient. Now such a combination is unacceptable - only blood with the appropriate recipient Rh factor is used. Therefore, today, during blood transfusion, 8 blood groups are distinguished - 4 positive (0 Rh+, A Rh+, B Rh+, AB Rh+) ​​and 4 negative (0Rh-, A Rh-, B Rh-, AB Rh-).

Since all components, including infections, enter the recipient's body with the donor's blood, the World Health Organization recommends that all donations be checked. First of all, we are talking about diseases that are transmitted through the blood and its components:

• Hepatitis B and C.
• Syphilis.

Until recently, blood transfusion was one of the main ways of transmitting hepatitis, today the percentage of infected people has decreased. But the risk still remains. Therefore, if the recipient needs systematic blood transfusion, it is best to choose regular donors and get vaccinated against hepatitis B.

If it is necessary to donate blood for a recipient with reduced immunity, it must be additionally tested for a number of other infections. Even if they do not affect the donor, they can lead to serious complications in the patient. For donation, blood is taken from a vein, an average of 400 ml.

Blood diseases

Under blood diseases unite different types diseases affecting formed elements and plasma. Often they become the result of bone marrow pathologies, because it is in it that leukocytes, erythrocytes and platelets are formed. In some cases, this category also includes diseases of other organs that significantly affect the level of blood, its composition, blood flow and the work of the cardiovascular system. For example, oxygen starvation can be caused both by problems with red blood cells and blockage of blood vessels due to cholesterol plaques.

The symptoms of this group of diseases are directly related to which particular shaped element suffers. So, with a decrease in the level of hemoglobin in the blood, people note such changes in well-being:

• General weakness.
• Vertigo.
• Fatigue.
• Body aches.

The lack of platelets is expressed in poorly healing wounds, the rapid formation of bruises, the inability to stop the blood, internal bleeding.

Often, human blood diseases pass without specific symptoms, are characterized by a general deterioration in well-being and proceed unnoticed for the patient at the first stages. With their development, body temperature may rise, pain in the bones may appear, fainting and other severe symptoms.

Laboratory signs of blood diseases

It is impossible to determine the disease by symptoms alone, so the final diagnosis is made on the basis of a decoding of a blood test. Moreover, for the initial diagnosis, a standard general study is quite sufficient.

RBC level

Red blood cells are responsible for the transport of oxygen to the cells and the timely removal of carbon dioxide. Therefore, if in the general blood test their number is below the norm, this is a sign of anemia (anemia).

If the level of red blood cells is elevated in the blood, this is also possible symptom diseases - polycythemia. This is a tumor process that is quite difficult and is treated much more difficult than anemia.

The analysis can also reveal atypical forms erythrocytes, which also affect their functions. For example, they reduce the lifespan of a cell.

Hemoglobin

It happens that the number of red blood cells does not change, but signs of anemia are still present. Most often, this indicates that there is not enough hemoglobin in red blood cells - the component that is responsible for attaching oxygen atoms. Therefore, in the blood test, the determination of the amount of this protein is highlighted in a separate item. Since it is hemoglobin that makes red blood cells red, the color factor is taken into account when deciphering blood - the protein content can be determined by color saturation.

Platelet level

Platelets provide normal blood clotting, and their reduced level, thrombocytopenia, is a direct threat to human life. After all, with such a disease, a small wound can cause massive blood loss. Against the background of a low level of platelets, the condition of the walls of blood vessels may worsen - they lose elasticity, become brittle. If the level of platelets in the blood is increased, this can lead to the formation of blood clots, blockage of small vessels and such consequences as the development of necrosis, including the kidney, myocardium, and brain cells.

WBC level

Leukocytes are responsible for immunity, and their reduced level (leukopenia) threatens with dangerous health consequences. With a slight deviation from the norm, the patient is more susceptible to infections, often suffers from seasonal diseases, it can be more difficult to endure illnesses, and receive complications. Leukopenia may present with drug treatment, often it accompanies such infectious diseases as measles, rubella. In such cases, the level of leukocytes is restored after treatment. However, a low level of these blood components can indicate serious diseases: tuberculosis, malignant tumors, bone marrow damage, and the presence of HIV infection.

Leukocytosis (elevated levels of white blood cells) may be a sign of a severe inflammatory process. The blood in children may contain an increased number of leukocytes, which is the norm and does not affect well-being.

Some indicators are not directly related to blood diseases, but they strongly affect the functioning of the cardiovascular system and other organs involved in the blood circulation process.

High cholesterol in the blood

A blood test for cholesterol is taken to determine the risk of developing atherosclerosis or coronary heart disease. It is advisable to conduct such an examination once a year, in a comprehensive preventive diagnosis by a cardiologist. By itself, this lipid is not dangerous, because it helps the arteries maintain the elasticity and integrity of the walls. However, this applies to the so-called "good" cholesterol - HDL. But another indicator, LDL, can lead to its sticking to the walls of blood vessels and the formation of plaques that narrow the lumen of the artery. A blood test is normal for total cholesterol - 3.6-7.8 mmol / l.

Increased bilirubin in the blood

Bilirubin is formed as a result of the breakdown of hemoglobin. This is a yellow blood pigment, an increase in the level of which gives jaundice - one of the important symptoms of damage to liver cells. Moreover, the severity of the disease can be different. For example, an increase in bilirubin is noted with ordinary poisoning, but may also indicate cirrhosis, hepatitis, and even an oncological process.

Allocate direct bilirubin, which appears in the blood when the outflow of bile is disturbed, and indirect - the result of increased breakdown of red blood cells. The liver is an important organ for blood, since it stores the largest supply of its deposited component.

Blood norm for bilirubin:

• General - 3.4-17.1 µmol / l.
• Direct - 0-7.9 µmol / l.
• Indirect - up to 19 µmol / l.

Increased creatinine in the blood

Creatinine is a metabolite, the end product of the breakdown of metabolic processes that occur in the muscles. And although a small amount of it is always in the plasma, the main percentage is excreted by the kidneys. If creatinine is elevated in the blood, this indicates a possible development, in particular kidney failure. Also, a high concentration of the metabolite indicates possible problems with muscles. However, only a doctor can correctly decipher a blood test, since creatinine easily rises and falls from physical activity, the use of certain foods, and even against a background of stress.

The kidneys are extremely important for the normal state of the blood, since it is here that it is filtered. Healthy kidneys can process 1700 liters of blood per day, that is, in about 3 minutes, its entire total volume passes through them. In the event that the kidneys do not cope with their functions, the blood becomes contaminated, the decay products begin to circulate through circulatory system and can harm other organs.

The norm of blood for creatinine:

• Men - 62-115 µmol / l.
• Women - 53-97 µmol / l.

Blood sugar

Testing glucose levels is the main way to diagnose diabetes. With an increase in blood sugar, the risk of developing cardiovascular diseases increases significantly. Including myocardial infarction, which against the background of type 1 diabetes can occur even in childhood. There is also a danger of overlapping peripheral vessels, and this in turn leads to suppuration, ulcers and even loss of limbs. Too much low sugar in the blood affects the general condition, hypoglycemia develops, which, without medical care leads to coma and death.

Today, blood sugar testing is one of the simplest. Diabetics monitor this indicator with the help of home glucometers, which give a result in less than a minute. Healthy people are recommended to undergo such an analysis at least once a year. The interpretation of a blood test depends on many factors, in particular, the last meal is taken into account.

Normal fasting glucose:

• Children under 14 years old - 3.33-5.55 mmol / l.
• Adults - 3.89-5.83 mmol / l.
• Elderly people - 4.44-6.38 mmol / l.

The most common blood disease is anemia (anemia), which is characterized by a decrease in hemoglobin/erythrocytes. The reasons for the lack of this protein can be caused by various factors. The most common is the iron deficiency form, provoked by a lack or poor absorption of iron. The most serious types of anemia are associated with disruption of the bone marrow and the pathology of formed elements: hemolytic is caused by the rapid destruction of red blood cells, aplastic is caused by growth inhibition or a complete cessation of blood cell production. Posthemorrhagic anemia, which develops against the background of various types of blood loss, including internal hemorrhages, is distinguished into a separate type.

However, despite the different etiology of diseases, they present a similar danger - oxygen starvation of the body and the consequences caused by it. There are three stages of anemia according to severity:

1. Light (hemoglobin above 90 g / l).
2. Medium (90-70 g / l).
3. Severe (less than 70 g/l).

The most severe forms require treatment with blood transfusion, and if anemia is caused by pathologies or diseases of the bone marrow, then blood transfusions are carried out as a course.

Iron-deficiency anemia

Among all diagnosed anemia, iron deficiency is in the first place. The fact is that most often it develops not against the background of pathology, but as a result of malnutrition. Low levels of hemoglobin in the blood can occur in vegetarians, populations living far from the sea, people who often follow strict diets.

Iron deficiency anemia also develops when the body needs an increased intake of iron. An example would be the period of pregnancy and menstruation.

Mild anemia caused by lifestyle is regulated without the use of medications, but with the help of dietary adjustments. The following products are introduced into the diet:

• Meat, liver.
• Fish, seafood.
• Green vegetables.
• Legumes (soybeans, lentils, peas).
• Apples.

In rare cases, the level of iron in the blood drops due to the fact that the body simply cannot absorb this element. The cause is various diseases of the gastrointestinal tract, in particular, atrophic gastritis, inflammatory diseases, cicatricial processes in small intestine. In this case, the treatment of anemia will be aimed at eliminating the main cause of anemia.

B12 deficiency anemia

The second most common anemia is caused by a lack of vitamin B12. First of all, it is necessary for nervous system, however, it also affects the bone marrow - with its deficiency, the production of red blood cells slows down. Anemia develops very slowly, often turning into chronic form with constant relapses. Unlike iron deficiency anemia, the main cause of this form of anemia is malabsorption of vitamin B12. Therefore, treatment is aimed primarily at eliminating diseases of the gastrointestinal tract.

This blood disease manifests itself with the following symptoms:

• Unsteadiness of gait.
• General weakness.
• Numbness and tingling in the fingers.
• Edema of the extremities.
• Burning and itching on the tip of the tongue.

Hemolytic anemia

Hemolytic anemia is associated with the rapid destruction of red blood cells - there is not enough hemoglobin in the blood, because the cells containing it simply do not have time to reproduce. Normally, erythrocytes live for about 120 days, with some types of such anemia, they can die already on the 12-14th day. Considering that hemoglobin is rapidly destroyed, the patient has common symptoms jaundice may appear, and bilirubin, a breakdown product of hemoglobin, will certainly be elevated in a biochemical blood test.

One of the reasons for such a short life of red blood cells may be their irregular shape. So, sickle cell anemia is characterized by elongated, pointed at the ends of the cells. Such red blood cells cannot function normally and are quickly destroyed. In addition, the wrong shape of blood cells can cause them to block blood vessels.

Another type of hemolytic anemia is caused by an autoimmune reaction. With it, red blood cells are destroyed by the cells of their own body, which perceive red blood cells as foreign elements.

aplastic anemia

Aplastic anemia occurs when the bone marrow fails to produce blood cells for various reasons. It differs from previous forms of anemia in that not only erythrocytes are affected, but also leukocytes and platelets. Past infections, radiation or heredity can lead to such violations. Aplastic forms of anemia are rare, easily determined by a general blood test, where all the formed components are indicated.

Hemophilia

Hemophilia is a bleeding disorder, but its causes do not lie in insufficient production of platelets, but in plasma disorders. In the liquid medium, there is a reduced level or absence of blood clotting protein VIII (Factor VIII). If such a deviation is detected during the decoding of a blood test, hemophilia A, or classic hemophilia, is diagnosed. There is also B, but it accounts for only 20% of all cases of this pathology. Both diseases are hereditary, and not only the type, but also the severity of the disease is transmitted to the offspring. Symptoms appear exclusively in men, but only women are carriers, since the disease is associated with a change in a gene on the X chromosome.

In hemophilia A, bleeding may not show up at first because the platelets that block the wound are working normally. But after a day, blood may begin to pour out of the damaged area, and in some cases it is impossible to stop it for months. Especially dangerous in this regard are small internal bleeding which the patient may simply not notice for a long time.

The main blood test for diagnosing hemophilia is the clotting factor, which not only shows the presence of the disease, but also its severity.

The disease is congenital and chronic, so the patient is prescribed replacement therapy with antihemophilic globulin concentrates for life. This treatment allows you to completely get rid of the symptoms of hemophilia. However, you need to start it as soon as possible, since constant bleeding can affect the health of the joints, muscles, internal organs.

Leukemias are a group of blood cancers in which cancer cells copy the bone marrow or produce mutated blood cells. In the first case, the degeneration of the bone marrow tissue leads to the fact that it cannot produce enough red blood cells, white blood cells and platelets. In the second, cancer cells gradually replace healthy ones in the total blood mass.

The reasons for this rebirth are not fully understood, but it is directly associated with impaired immunity. For the development of the disease, one stem cell is enough, which begins to produce pathologically altered shaped elements.

Leukemias are acute and chronic. The first are very difficult and require immediate treatment. By type, these are different diseases, since they are associated with the formation of different types of cancer cells. Therefore, acute leukemia cannot become chronic, and vice versa.

On the initial stage Symptoms of blood cancer are similar to SARS:

• Temperature rise.
• Body aches.
• Pallor.
• Vertigo.
• Perhaps the appearance of red spots, as a result of subcutaneous hemorrhages.

The disease is diagnosed by a general and biochemical blood test, as well as bone marrow studies. The patient is prescribed chemotherapy, and if it does not help, bone marrow transplantation.

Encyclopedic YouTube

1 / 3

✪ What is blood made of

✪ The internal environment of the body. Composition and functions of blood. Biology video lesson Grade 8

✪ BTS "Blood Sweat & Tears" mirrored Dance Practice

Subtitles

I don't like to do this, but from time to time I need to donate blood. The thing is that I'm afraid to do it, just like a small child. I really don't like injections. But of course I force myself. I donate blood and try to distract myself while the blood fills the needle. Usually I turn away, and everything passes quickly and almost imperceptibly. And I leave the clinic absolutely happy, because everything is over and I don’t have to think about it anymore. Now I want to trace the path that blood takes after it has been taken. At the first stage, the blood enters the test tube. This happens directly on the day of blood sampling. Usually such a test tube is at the ready and waiting for blood to be poured into it. This is the lid of my vial. Draw blood inside the test tube. Full vial. This is not a simple test tube, its walls are coated with a chemical that prevents blood from clotting. Blood clotting should not be allowed, as this will make further research extremely difficult. That is why a special test tube is used. The blood won't clot in it. To make sure that everything is in order with her, the tube is shaken slightly, checking the density of the sample .. Now the blood enters the laboratory. There is a special apparatus in the laboratory that receives my blood and the blood of other people who visited the clinic that day. All of our blood is labeled and put into the machine. And what does the machine do? It spins fast. Spins really fast. All test tubes are fixed, they will not fly away, and, accordingly, they spin in this apparatus. By rotating the test tubes, the apparatus creates a force called "centrifugal force". The whole process is called "centrifugation". Let's write it down. Centrifugation. And the apparatus itself is called a centrifuge. Test tubes with blood rotate in any direction. And as a result, the blood begins to separate. Heavy particles go to the bottom of the tube, and the less dense part of the blood rises to the lid. After the blood in the tube has been centrifuged, it will look like this. Now I will try to depict it. Let it be a test tube before rotation. Before rotation. And this is the tube after rotation. This is her after view. So, what does the tube look like after centrifugation? The key difference will be that instead of the homogeneous liquid that we had, we get an externally completely different liquid. Three different layers are distinguishable, which I will now draw for you. So, this is the first layer, the most impressive, making up most of our blood. He is up here. It has the smallest density, which is why it remains near the lid. In fact, it makes up almost 55% of the total blood volume. We call it plasma. If you've ever heard the word plasma, now you know what it means. Let's take a drop of plasma and try to find out its composition. 90% of plasma is just water. Interesting, isn't it. Just water. The main part of blood is plasma and most of it is water. Most of the blood is plasma, most of the plasma is water. That's why people are told to "drink more water so you don't get dehydrated" because most blood is water. This is true for the rest of the body, but in this case I am focusing on the blood. So what's left? We already know that 90% of plasma is water, but it's not all 100%. 8% of plasma consists of protein. Let me show you some examples of such a protein. This is albumin. Albumin, if you're unfamiliar with it, is an important protein in blood plasma that makes it impossible for blood to leak out of blood vessels. Another important protein is the antibody. I'm sure you've heard of it, antibodies are linked to our immune system. They make sure that you are beautiful and healthy, do not suffer from infections. And another type of protein to keep in mind is fibrinogen. fibrinogen. It takes a very active part in blood clotting. Of course, in addition to it, there are other coagulation factors. But about them - a little later. We have listed proteins: albumin, antibody, fibrinogen. But we still have 2%, they are substances such as hormones, insulin, for example. There are also electrolytes. For example, sodium. Also in this 2% are nutrients. such as glucose. All these substances make up our plasma. Many of the substances we talk about when we talk about blood are found in plasma, including vitamins and other similar substances. Now consider the next layer, which is directly below the plasma and highlighted in white. This layer makes up a very small part of the blood. Less than 1%. And form its white blood cells, as well as platelets. platelets. These are the cellular parts of our blood. There are very few of them, but they are very important. Beneath this layer is the densest layer, the red blood cells. This is the last layer, and its share will be approximately 45%. Here they are. Red blood cells, 45%. These are red blood cells that contain hemoglobin. It should be noted here that not only plasma contains proteins (which we mentioned at the beginning of the video), white and red blood cells also contain a very large amount of proteins, which should not be forgotten. An example of such a protein is hemoglobin. Now whey is a word you've probably heard. What is it? Serum is practically the same as plasma. Now I will circle everything that is part of the serum. Everything circled in blue is serum. I did not include fibrinogen and clotting factors in the serum. So, plasma and serum are very similar except that there is no fibrinogen and no clotting factors in serum. Let's look at red blood cells now, what can we learn? You may have heard the word hematocrit. So the hematocrit is 45% of the blood volume in this figure. This means that the hematocrit is equal to the volume occupied by red blood cells divided by the total volume. In this example, the total volume is 100%, the red blood cell volume is 45%, so I know that the hematocrit would be 45%. This is simply the percentage that red blood cells make up. And it is very important to know it, since red blood cells carry oxygen. In order to emphasize the meaning of hematocrit, as well as to introduce some new words, I will draw three small tubes of blood. Let's say I have three test tubes: one, two, three. They contain the blood of different people. But these people are of the same sex and age, since the amount of hematocrit depends on age, gender, and even on what altitude you live at. If you live on a mountaintop, your hematocrit will be different from that of a plains dweller. Hematocrit is influenced by many factors. We have three people who are very similar in such factors. The blood plasma of the first person, I will draw it here, occupies such a fraction of the total volume of blood. The plasma of the second occupies just such a part of the total blood volume. And the plasma of the third occupies the largest part of the total blood volume, say, the entire volume to the bottom. So, you scrolled through all three test tubes, and this is what you got. Of course, all three have white blood cells, I'll draw them. And everyone has platelets, we said that this is a thin layer of less than 1%. And the rest are red blood cells. This is the layer of red blood cells. The second person has a lot of them. And the third has the least. Red blood cells do not occupy much of the total volume. So, if I had to assess the condition of these three people, I would say that the first person is fine. The second one has a lot of red blood cells. They are outnumbered. We see a really high percentage of red blood cells. Really big. So I can conclude that this man has polycythemia. Polycythemia is a medical term meaning that the number of red blood cells is very high. In other words, he has an elevated hematocrit. And this third person has a very low number of red blood cells in relation to the total volume. Conclusion: He is anemic. If you now hear the term "anemia", or "polycythemia", you will know that we are talking about how much of the total blood volume is occupied by red blood cells. See you in the next video. Subtitles by the Amara.org community

blood properties

• Suspension properties depend on the protein composition of blood plasma, and on the ratio of protein fractions (normally, there are more albumins than globulins).
• Colloidal Properties associated with the presence of proteins in plasma. Due to this, the constancy of the liquid composition of the blood is ensured, since protein molecules have the ability to retain water.
• Electrolyte properties depend on the content of anions and cations in the blood plasma. The electrolyte properties of blood are determined by the osmotic pressure of the blood.

Composition of the blood

The entire blood volume of a living organism is conditionally divided into peripheral (located and circulating in the bloodstream) and blood located in the hematopoietic organs and peripheral tissues. Blood is made up of two main components: plasma and weighed in it shaped elements. The settled blood consists of three layers: the upper layer is formed by yellowish blood plasma, the middle, relatively thin gray layer is made up of leukocytes, the lower red layer is formed by erythrocytes. In an adult healthy person, the plasma volume reaches 50-60% of whole blood, and the blood cells make up about 40-50%. The ratio of blood cells to its total volume, expressed as a percentage or presented as a decimal fraction with an accuracy of hundredths, is called the hematocrit number (from other Greek. αἷμα - blood, κριτός - indicator) or hematocrit (Ht). Thus, hematocrit is the part of the blood volume attributable to erythrocytes (sometimes defined as the ratio of all formed elements ( erythrocytes, leukocytes, platelets) to the total blood volume). The determination of hematocrit is carried out using a special glass graduated tube - hematocrit, which is filled with blood and centrifuged. After that, it is noted which part of it is occupied by blood cells (leukocytes, platelets and erythrocytes). In medical practice, the use of automatic hematological analyzers is increasingly being used to determine the hematocrit (Ht or PCV).

Plasma

Shaped elements

In an adult, blood cells make up about 40-50%, and plasma - 50-60%. The formed elements of the blood are erythrocytes, platelets And leukocytes:

• Erythrocytes ( red blood cells) are the most numerous of the formed elements. Mature erythrocytes do not contain a nucleus and are shaped like biconcave discs. They circulate for 120 days and are destroyed in the liver and spleen. Red blood cells contain an iron-containing protein - hemoglobin. It provides the main function of red blood cells - the transport of gases, primarily oxygen. Hemoglobin is what gives blood its red color. In the lungs, hemoglobin binds oxygen, turning into oxyhemoglobin which is light red in color. In tissues, oxyhemoglobin releases oxygen, re-forming hemoglobin, and the blood darkens. In addition to oxygen, hemoglobin in the form of carbohemoglobin carries carbon dioxide from the tissues to the lungs.

Blood is required for victims of burns and injuries, as a result of massive bleeding: during complex operations, in the process of difficult and complicated childbirth, and for patients with hemophilia and anemia - to maintain life. Blood is also vital for cancer patients during chemotherapy. Every third inhabitant of the Earth needs donated blood at least once in his life.

Blood taken from a donor (donor blood) is used for research and educational purposes; in the production of blood components, medicines and medical products. The clinical use of donated blood and (or) its components is associated with transfusion (transfusion) to the recipient for therapeutic purposes and the creation of stocks of donor blood and (or) its components.

Blood diseases

• Anemia (gr. αναιμία anemia) - a group of clinical and hematological syndromes, the common point for which is a decrease in the concentration of hemoglobin in the circulating blood, more often with a simultaneous decrease in the number of erythrocytes (or the total volume of erythrocytes). The term "anemia" without specification does not define a specific disease, that is, anemia should be considered one of the symptoms of various pathological conditions;
• Hemolytic anemia - increased destruction of red blood cells;
• Hemolytic disease of the newborn (HDN) - pathological condition a newborn, accompanied by a massive breakdown of erythrocytes, in the process of hemolysis caused by an immunological conflict between the mother and fetus as a result of incompatibility of the blood of the mother and fetus according to the blood group or Rh factor. Thus, the formed elements of the fetal blood become foreign agents (antigens) for the mother, in response to which antibodies are produced that penetrate the hematoplacental barrier and attack the fetal erythrocytes, as a result of which massive intravascular hemolysis of erythrocytes begins in the first hours after birth. It is one of the main causes of jaundice in newborns;
• Hemorrhagic disease of newborns is a coagulopathy that develops in a child between 24 and 72 hours of life and is often associated with a lack of vitamin K, due to a deficiency of which there is a lack of biosynthesis in the liver of blood coagulation factors II, VII, IX, X, C, S. Treatment and prevention consists in addition to the diet of newborns shortly after the birth of vitamin K;
• Hemophilia - low blood clotting;
• Disseminated intravascular clotting blood - the formation of microthrombi;
• Hemorrhagic vasculitis ( allergic purpura) - the most common disease from the group of systemic vasculitis, which is based on aseptic inflammation of the walls of microvessels, multiple microthrombosis, affecting the vessels of the skin and internal organs (most often the kidneys and intestines). The main reason causing clinical manifestations this disease- circulation of immune complexes and activated components of the complement system in the blood;
• Idiopathic thrombocytopenic purpura ( Disease Werlhof) - a chronic undulating disease, which is a primary hemorrhagic diathesis, due to quantitative and qualitative insufficiency of the platelet link of hemostasis;
• Hemoblastosis is a group of neoplastic blood diseases, conditionally divided into leukemic and non-leukemic:
  • Leukemia (leukemia) is a clonal malignant (neoplastic) disease of the hematopoietic system;
• Anaplasmosis is a form of blood disease in domestic and wild animals, the carriers of which are ticks of the genus Anaplasma (lat. Anaplasma) of the lat family. Ehrlichiaceae.

Pathological conditions

• Hypovolemia - a pathological decrease in the volume of circulating blood;
• Hypervolemia - a pathological increase in the volume of circulating blood;