Non-protein nitrogenous components of blood. Basic blood constants

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

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

Plasma devoid of fibrinogen is called serum.

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

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

Rice. 2. Blood composition

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

Red blood cells

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

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

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

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

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

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

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

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

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

Hemolysis and its causes

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

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

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

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

Erythrocyte sedimentation rate (ESR)

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

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

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

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

Leukocytes

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

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

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

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

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

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

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

Agranulocytes are divided into monocytes and lymphocytes.

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

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

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

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

Null lymphocytes do not differentiate in organs immune system, but if necessary, they can turn into B- and T-lymphocytes.

The number of lymphocytes increases when microorganisms penetrate the body.

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

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

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

Platelets

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

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

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

Blood constants

Basic blood constants

Blood like liquid tissue The body is characterized by many constants, which can be divided into soft and hard.

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

The amount of blood circulating through the vessels

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

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

Erythrocyte sedimentation rate

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

Blood viscosity

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

Specific gravity (relative density) of blood

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

Hard constants

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

Constancy of blood ion composition

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

The amount of proteins in plasma

Functions of proteins:

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

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

Blood osmotic pressure

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

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

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

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

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

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

Content of oxygen and carbon dioxide in the blood

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

blood pH

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

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

Blood, sanguis is a special tissue consisting of formed elements (40-45%) and liquid intercellular substance - plasma (55-60% of blood volume).

Blood circulates in blood vessels and is separated from other tissues vascular wall, however, formed elements, as well as blood plasma, can pass into the connective tissue surrounding the blood vessels. Thanks to this, blood ensures the constancy of the composition of the internal environment of the body.

Blood functions:

1. Transport

Respiratory (transport of oxygen and carbon dioxide)

Excretory (transport of metabolic products - uric acid, bilirubin, etc. to the excretory organs - kidneys, intestines, skin, etc.)

Nutritional (transport of glucose, amino acids, etc.)

Homeostatic (uniform distribution of blood between organs and tissues, maintaining constant osmotic pressure and pH with the help of blood plasma proteins, etc.)

2. Protective (neutralization of microorganisms, toxins, tissue breakdown products, formation of antibodies, blood clot formation)

3. Regulatory

Regulatory (hormone transport)

Thermoregulatory (transfer of heat outward from deep-lying organs to the vessels of the skin, uniform distribution of heat in the body due to the high heat capacity and thermal conductivity of the blood)

In humans, blood mass is 6-8% of body weight (4.5-5 l). At rest, 40-50% of all blood circulates, the rest is in the depot (liver, spleen, skin). The pulmonary circulation contains 20-25% of the blood volume, and the large circulation contains 75-80%. 15-20% of the blood circulates in the arterial system, 70-75% in the venous system, and 5-7% in the capillaries.

Blood composition:

1. formed elements – 40-45% of blood volume

2. blood plasma (intercellular substance) – 55-60% of blood volume (approx. 3 l)

Plasma can be obtained by centrifuging blood - this is a liquid, light yellow part of the blood, without formed elements.

Blood plasma 90% consists of water, in which salts and low molecular weight organic substances are dissolved, and also contains lipids, proteins and their complexes. Proteins (7-8%) are presented:

Fibrinogen, involved in the blood clotting process

Albumin (60% proteins), low molecular weight proteins that transport poorly soluble substances, incl. medicinal

Antibody-forming globulin (high molecular weight protein)

Plasma ensures the constancy of the volume of intravascular fluid and acid-base balance (ABC), participates in the transfer active substances and metabolic products.

Blood plasma devoid of fibrinogen is called serum . The whey does not coagulate. The serum remains after blood clotting (when the clot is removed).

Formed elements of blood are divided into:

1. red blood cells,

2. leukocytes and

3. platelets.

All formed elements of blood are formed in the bone marrow from a stem cell, from there they enter the venous blood. All cells perform specific functions, but at the same time, they all participate in the transport of various substances and perform protective and regulatory functions.

The number of formed elements per unit volume of blood is called hemogram- This clinical analysis blood. Includes data on the amount of all formed elements of blood, their morphological features, ESR, hemoglobin content, the ratio of different types of leukocytes, etc.

Red blood cells – were first discovered in the blood of a frog by Malpighius (1661), and Leeuwenhoek showed that they are also present in human blood (1673). These are highly specialized anucleate cells with a diameter of 7-8 microns, shaped like a biconcave disk (the surface area of ​​such a disk is 1.7 times greater than spheres of the same diameter). Red blood cells are highly elastic; they easily pass through capillaries, which have half the diameter of the cell itself.

The lifespan of an erythrocyte is about 3 months. Red blood cells are formed in the red bone marrow from precursor cells that lose their nucleus before entering the bloodstream, and die (destroyed) in the spleen and liver.

Functions of red blood cells:

1. Respiratory - hemoglobin is able to bind 70 times more oxygen than dissolved in plasma

2. Nutritional – amino acids are adsorbed on the surface

3. Protective – capable of binding toxins due to antibodies on the surface, and also participate in blood clotting

4. Enzymatic – they are carriers of enzymes.

The cytoplasm of the erythrocyte contains a special protein chromoprotein - hemoglobin, which consists of a protein (globin) and iron-containing (hem) part. Occupies 25% of the erythrocyte volume. For every 1 globin molecule there are 4 heme molecules. A Hb molecule can be associated with 4 oxygen molecules. Fe(II) atoms impart to individual red blood cells in fresh blood yellow, and the blood itself (many red blood cells) is red. Normally, the blood contains 140 g/l of hemoglobin (women 135-140 g/l, men 135-155 g/l). The content of hemoglobin in erythrocytes is judged by the color indicator (percentage ratio of hemoglobin and erythrocytes), which is normally 0.75-1.0. The main purpose of hemoglobin is the transport of oxygen and carbon dioxide; in addition, it has buffering properties and is able to bind toxic substances.

After the destruction of red blood cells in the spleen, iron atoms are used mainly for the needs of the body; part of the heme is converted into bile pigments (bilirubin and biliverdin), which determine the color of urine and feces.

Types of hemoglobin:

§ Hemoglobin that has added oxygen is called oxyhemoglobin,

§ giving up oxygen – reduced or reduced hemoglobin.

Oxyhemoglobin predominates in arterial blood, which gives it a scarlet color. In venous blood up to 35% of reduced hemoglobin.

§ In addition, part of the hemoglobin binds with carbon dioxide, forming carbohemoglobin, due to which 10 to 20% of all CO 2 transported in the blood is transferred.

§ Carboxyhemoglobin is a compound of hemoglobin and carbon monoxide, which is 300 times easier to attach to hemoglobin than oxygen. Therefore, hemoglobin, which has attached CO, is not able to bind to O2. In case of poisoning carbon monoxide vomiting is observed, headache, loss of consciousness; it is necessary to give pure oxygen to breathe, which accelerates the breakdown of carboxyhemoglobin. Normally - about 1% carboxyhemoglobin, in smokers - 3-10%.

§ Strong oxidizing agents (ferrocyanide, hydrogen peroxide, etc.) change the charge of iron from 2+ to 3+, resulting in the formation of oxidized hemoglobin - methemoglobin, which very firmly retains oxygen, while oxygen transport is disrupted. Has a brown color. It is more common among people employed in hazardous chemicals. Production, as well as with excessive consumption of drugs with oxidizing properties.

§ Myoglobin is a respiratory pigment found in muscles; its structure is similar to hemoglobin; is able to bind a much larger amount of oxygen and therefore performs a storage function (oxygen supply in the muscles)

The blood contains 4-4.5 million red blood cells/ml in women and 4.5-5 million red blood cells/ml in men. Increased quantity erythrocytes (erythrocytosis) in residents of high mountains, in athletes, in children, with hypoxia, congenital defects heart, cardiovascular failure. A decrease in the amount of hemoglobin in red blood cells is called anemia. The destruction of red blood cells, in which hemoglobin is released into the plasma, is called hemolysis. In this case, the blood takes on a lacquered color. Hemolysis can be caused by chemical agents that destroy the red blood cell membrane (acetic acid poisoning, some snake bites); mechanical hemolysis - when shaking an ampoule with blood, in patients with cardiac valve prostheses, during prolonged walking; immune hemolysis - due to transfusion of incompatible blood.

The specific density of erythrocytes is higher than the density of plasma (1.096 and 1.027), therefore, erythrocyte sedimentation occurs in a vertical test tube (sodium citrate must be added to the blood to prevent blood clotting). The erythrocyte sedimentation rate (ESR) characterizes some physicochemical characteristics blood. The greatest influence on the ESR value is exerted by the fibrinogen content (more than 4 g/l ESR increases), therefore ESR depends more on the properties of plasma than erythrocytes. ESR in men is normal 5-7 mm/h, in women 8-12 to 15 mm/h. Increased ESR typical for pregnant women - up to 30 mm/h, patients with infectious and inflammatory diseases, as well as with malignant tumors– up to 50 or more mm/h.

Hemoglobin is a chromoprotein and contains protein - globin. A solution of such a substance in plasma would increase blood viscosity several times. This would lead to increased blood pressure and the heart would have to pay the price.

Leukocytes – spherical cells, unlike red blood cells, have a nucleus. The size of a leukocyte is up to 20 microns. The lifespan of a leukocyte is several days. 1 ml of blood contains 4-9 thousand leukocytes. The number of leukocytes changes throughout the day, least of all in the morning on an empty stomach. An increase in the number of leukocytes in the blood is leukocytosis, a decrease is leukopenia.

They are formed in the red bone marrow from stem cells, in the spleen, thymus, and lymph nodes. They are destroyed in the spleen and liver.

The lifespan of leukocytes is on average several. Day to several days Tens of days. More than 50% of leukocytes are located outside the vascular cortex - in various tissues.

Leukocytes are capable of active movement (like amoebas); they can penetrate through the capillary wall into the surrounding connective and epithelial tissue and participate in defensive reactions body (digestion of foreign bodies, microorganisms, formation of antibodies).

Leukocytes may have granularity (granules) in the cytoplasm - g ranulocytes, which are non-granular - agranulocytes. The granules can be painted in various colors. Depending on the color of the granules, granulocytes are divided into:

- eosinophils(colored with acidic dyes in pink color) – capable of neutralizing foreign proteins and proteins of dead tissue. The number of eosinophils increases during allergic reactions.

- basophils(colored with basic dyes in Blue colour) - take part in blood clotting and regulation of vascular permeability for formed elements. Basophils produce heparin and histamine.

- neutrophils(colored with neutral dyes in pink-violet color) - are able to penetrate into intercellular spaces and capture and digest microorganisms, stimulate cell reproduction. Dead neutrophils, together with the remains of cells and tissues, form pus.

Agranulocytes are leukocytes that consist of a rounded nucleus and non-granular cytoplasm. They are divided into lymphocytes and monocytes.

Lymphocytes– spherical, with a diameter of 7-10 microns. They consist of two populations: lymphocytes formed in the thymus gland (thymus) - T-lymphocytes (responsible for the cellular immunity system and, with the help of enzymes, independently destroy foreign cells, including mutated ones, counteract pathogenic viruses, fungi - T-killers, reinforcing cellular immunity or facilitating the course of humoral immunity T-helpers, interfering with immunity during recovery T-suppressors, memory T cells - store information about previously active antigens, i.e. accelerate the secondary immune response) and B-lymphocytes formed from stem lymphoid cells bone marrow and spleen, lymphoid accumulations of the wall of the small intestine, tonsils, lymph nodes(they are responsible for the humoral immune system and protect the body from bacteria and viruses by producing special proteins - antibodies). The lifespan of lymphocytes is from 3 days to 6 months, and some – up to 5 years.

Monocytes– the largest blood cells, size up to 20 microns. Formed in the bone marrow. They actively penetrate into areas of inflammation and absorb (phagocytose) bacteria.

The ratio of blood cells is called a hemogram (blood formula), the percentage of different types of leukocytes is called leukocyte formula:

Leukocytes 4-9 *10 9 /l

Eosinophils 1-5%

Basophils 0-0.5%

Neutrophils 60-70%: young 0-1%, band 2-5%,

segmented 55-68%

Lymphocytes 25-30%

Monocytes 5-8%

In the blood of a healthy person, mature and young forms of leukocytes can be found, but normally they can be detected only in the largest group - neutrophils. These include young and band neutrophils. An increase in the number of young and band neutrophils indicates rejuvenation of the blood and is called shift of the leukocyte formula to the left, often observed in leukemia, infectious and inflammatory diseases. For a number of diseases, the amount individual species leukocytes increases. With whooping cough, typhoid fever– lymphocytes, in case of malaria – monocytes, in case of bacterial infections– neutrophils, in allergic reactions – eosinophils.

Platelets– colorless polymorphic anucleate bodies 1-4 microns in size, contain a large number of granules. Platelets are formed in bone marrow cells called megakaryocytes. Their lifespan is 5-11 days. 1 ml of blood contains 180-320 to 400 thousand platelets. During muscular work, stress, eating, pregnancy, the number of platelets increases (thrombocytosis). The main purpose of platelets is to participate in the process of hemostasis (help stop bleeding). When the integrity of the vessel wall is violated, platelets are destroyed and release a specific substance that promotes blood clotting.

When activated, platelets acquire a spherical shape and form special outgrowths (pseudopodia), with the help of which they can connect with each other (aggregate) and adhere to the damaged vessel wall. Platelets contain fibrinogen, as well as the contractile protein thrombastenin. They are rich in glycogen, serotonin (constricts blood vessels), histamine, and contain inactive thromboplastin (triggers coagulation).

Lymph- fluid returned to the bloodstream from tissue spaces through the lymphatic system. Lymph is formed from tissue fluid that accumulates in the intercellular space. Most important function lymph is the return of proteins, electrolytes and water from the interstitial space into the blood. More than 100g is returned per day. squirrel. The lymphatic system acts as a transport system to remove red blood cells remaining in the tissues after bleeding, as well as to remove and neutralize bacteria trapped in the tissues. It consists of plasma and formed elements. Lymphoplasm, unlike blood, contains more metabolic products coming from tissues. Of the formed elements in lymph, lymphocytes predominate (up to 20,000/ml); monocytes and eosinophils are found in small quantities.

Hematopoiesis (lat. haemopoiesis), hematopoiesis is the process of formation, development and maturation of blood cells - leukocytes, erythrocytes, platelets in vertebrates.

Highlight:

• -embryonic (intrauterine) hematopoiesis;
• - postembryonic hematopoiesis.

The precursors of all blood cells are hematopoietic stem cells of the bone marrow, which can differentiate in two ways: into the precursors of myeloid cells (myelopoiesis) and into the precursors of lymphoid cells (lymphopoiesis).

Red blood cells circulate for 120 days and are destroyed in the liver and spleen.

The average lifespan of platelets is about one week. The lifespan of most leukocytes is from several hours to several months. Neutrophilic leukocytes (neutrophils) make up 95% of granular leukocytes. They circulate in the blood for no more than 8-12 hours, and then migrate into the tissues.

Regulation of hematopoiesis - hematopoiesis or hematopoiesis occurs under the influence of various growth factors, which ensure the division and differentiation of blood cells in the red bone marrow. There are two forms of regulation: humoral and nervous. Nervous regulation occurs when adrenergic neurons are excited, and hematopoiesis is activated, and when cholinergic neurons are excited, hematopoiesis is inhibited.

Humoral regulation occurs under the influence of factors of exo- and endogenous origin. Endogenous factors include: hematopoietins (products of the destruction of formed elements), erythropoietins (formed in the kidneys when the oxygen concentration in the blood decreases), leukopoietins (formed in the liver), thrombocytopoietins: K (in plasma), C (in the spleen). Exogenous vitamins: B3 - formation of erythrocyte stroma, B12 - formation of globin; trace elements (Fe, Cu...); external factor Castle. And also such growth factors as: interleukins, colony-stimulating factors CSF, transcription factors - special proteins that regulate the expression of genes of hematopoietic cells. In addition, the bone marrow stroma plays an important role, which creates the hematopoietic microenvironment necessary for the development, differentiation and maturation of cells.

Thus, the regulation of hematopoiesis is a single system consisting of several interconnected links of the cascade mechanism, which responds to changing conditions of the external and internal environment and various pathological conditions (with severe anemia - a decrease in the content of erythrocytes, a decrease in the content of leukocytes, platelets, blood clotting factors, acute blood loss, etc.). Inhibition of hematopoiesis occurs under the influence of inhibitory factors. These include products formed by cells on last stages maturation

It is important for patients with pathologies of the hematopoietic system to know what the lifespan of red blood cells is, how aging and destruction of red cells occurs, and what factors reduce their lifespan.

The article discusses these and other aspects of the functioning of red blood cells.

United circulatory system in the human body it is formed by blood and organs involved in the production and destruction of blood cells.

The main purpose of blood is transportation, maintenance water balance tissues (adjusting the ratio of salt and proteins, ensuring the permeability of vascular walls), protection (supporting human immunity).

The ability to clot is the most important property of blood, necessary to prevent heavy blood loss in the event of damage to body tissues.

The total blood volume in an adult depends on body weight and is approximately 1/13 (8%), that is, up to 6 liters.

IN children's body the blood volume is relatively larger: in children under one year of age - up to 15%, after one year - up to 11% of body weight.

The total volume of blood is maintained at a constant level, while not all of the available blood moves through the blood vessels, some part is stored in blood depots - the liver, spleen, lungs, and skin vessels.

Blood consists of two main parts - liquid (plasma) and formed elements (erythrocytes, leukocytes, platelets). Plasma occupies 52–58% of the total, blood cells account for up to 48%.

The formed elements of blood include erythrocytes, leukocytes and platelets. The factions play their role, and in healthy body the number of cells in each fraction does not exceed certain acceptable limits.

Platelets, together with plasma proteins, help clot blood and stop bleeding, preventing excessive blood loss.

Leukocytes - white blood cells - are part of the human immune system. Leukocytes protect the human body from exposure foreign bodies, recognize and destroy viruses and toxins.

Due to their shape and size, white bodies leave the bloodstream and penetrate the tissues, where they perform their main function.

Erythrocytes are red blood cells that transport gases (mostly oxygen) due to the protein hemoglobin they contain.

Blood is a rapidly regenerating tissue type. Renewal of blood cells occurs due to the breakdown of old elements and the synthesis of new cells, which occurs in one of the hematopoietic organs.

IN human body The bone marrow is responsible for the production of blood cells; the spleen is the blood filter.

The role and properties of red blood cells

Erythrocytes are red blood cells that perform a transport function. Thanks to the hemoglobin they contain (up to 95% of the cell mass), blood bodies deliver oxygen from the lungs to the tissues and carbon dioxide in the opposite direction.

Although the cell diameter is from 7 to 8 microns, they easily pass through capillaries whose diameter is less than 3 microns due to the ability to deform their cytoskeleton.

Red blood cells perform several functions: nutritional, enzymatic, respiratory and protective.

Red cells transport amino acids from digestive organs to cells, transport enzymes, carry out gas exchange between the lungs and tissues, bind toxins and promote their removal from the body.

The total volume of red cells in the blood is enormous; red blood cells are the most numerous type of blood element.

When conducting general analysis blood in the laboratory, the concentration of bodies is calculated in a small volume of material - 1 mm 3.

Acceptable values ​​of red blood cells in the blood vary for different patients and depend on their age, gender and even place of residence.

The increased number of red blood cells in infants in the first days after birth is explained by the high oxygen content in the blood of children during intrauterine development.

An increase in the concentration of red blood cells helps protect the child’s body from hypoxia when there is insufficient oxygen supply from the mother’s blood.

Residents of the highlands are characterized by a change normal indicators red cells to the larger side.

Moreover, when changing place of residence to flat terrain, the values ​​of erythrocyte volume return to general norms.

Both an increase and a decrease in the number of red bodies in the blood is considered one of the symptoms of the development of pathologies of internal organs.

An increase in the concentration of red blood cells is observed in kidney diseases, COPD, heart defects, and malignant tumors.

A decrease in the number of red blood cells is typical for patients with anemia of various origins and cancer patients.

Red cell formation

The common material of the hematopoietic system for the formed elements of blood are considered to be pluripotent undifferentiated cells, of which various stages synthesis produces red blood cells, leukocytes, lymphocytes and platelets.

When these cells divide, only small part remains as stem cells preserved in the bone marrow, and with age the number of original mother cells naturally decreases.

Most of the resulting bodies differentiate, and new types of cells are formed. Red blood cells are produced inside the blood vessels of the red bone marrow.

The process of creating blood cells is regulated by vitamins and microelements (iron, copper, manganese, etc.). These substances accelerate the production and differentiation of blood components and participate in the synthesis of their components.

Hematopoiesis is also regulated by internal factors. The breakdown products of blood elements become a stimulator for the synthesis of new blood cells.

Erythropoietin plays the role of the main regulator of erythropoiesis. The hormone stimulates the formation of red blood cells from previous cells and increases the rate of release of reticulocytes from the bone marrow.

Erythropoietin is produced in the adult body by the kidneys, and a small amount is produced by the liver. The increase in red blood cell volume is explained by a lack of oxygen in the body. The kidneys and liver more actively produce the hormone in case of oxygen starvation.

The average lifespan of red blood cells is 100 – 120 days. In the human body, the depot of red blood cells is constantly renewed, which is replenished at a rate of up to 2.3 million per second.

The differentiation process of red blood cells is strictly monitored to maintain a constant number of circulating red cells.

The key factor influencing the time and rate of red blood cell production is the concentration of oxygen in the blood.

The red blood cell differentiation system is highly sensitive to changes in oxygen levels in the body.

Aging and death of red blood cells

The lifespan of red blood cells is 3-4 months. Red blood cells are then removed from the circulatory system to eliminate them excess accumulation in vessels.

It happens that red cells die immediately after formation in the bone marrow. Lead to the destruction of red blood cells early stage formation can be caused by mechanical damage (trauma leads to damage to blood vessels and the formation of a hematoma, where red blood cells are destroyed).

The absence of mechanical resistance to blood flow affects the lifespan of red blood cells and increases their service life.

Theoretically, if deformation is excluded, red blood cells can circulate through the blood indefinitely, but such conditions are impossible for human vessels.

During their existence, red blood cells receive multiple damage, as a result of which the diffusion of gases through the cell membrane deteriorates.

The efficiency of gas exchange is sharply reduced, so these red blood cells must be removed from the body and replaced with new ones.

If damaged red blood cells are not destroyed in time, their membrane begins to collapse in the blood, releasing hemoglobin.

A process that should normally take place in the spleen occurs directly in the bloodstream, which can lead to protein entering the kidneys and causing kidney failure.

Obsolete red blood cells are removed from the bloodstream by the spleen, bone marrow and liver. Macrophages recognize cells that have been circulating in the blood for a long time.

Such cells contain a low number of receptors or are significantly damaged. The red blood cell is engulfed by the macrophage and iron ions are released in the process.

In modern medicine when treating diabetes mellitus data about red blood cells (what is their life expectancy, which affects the production of blood cells) plays an important role because it helps determine the content of glycated hemoglobin.

Based on this information, doctors can understand how much the blood sugar concentration has increased over the past 90 days.

The main component that forms the internal environment of the human body is blood. Among all body tissues, it is the only one with a liquid base; its volume is from 4 to 6 liters. In newborn babies, the amount of blood is approximately 200 - 350 ml. Blood circulation occurs through a closed system of vessels under the influence of rhythmic contractions of the heart and does not have direct communication with other tissues (histohematological barriers are responsible for this). In the human body, blood is formed from special stem cells (their number reaches 30,000), which are located mainly in the bone marrow, but also some of them are found in the small intestine, lymph nodes, thymus and spleen.

Blood is a rapidly renewing tissue. Physiological regeneration constituent elements occurs as a result of the breakdown of old cells and the formation of new ones in hematopoietic organs. IN human body the main such organ is the bone marrow, which is located in large tubular and pelvic bones. The main filtering organ for blood is the spleen, which is also responsible for the immunological control of the blood.

Components blood:

• plasma – liquid system;
• blood cells - platelets, erythrocytes, leukocytes.

Main functions of blood:

1. Respiratory - transportation of carbon dioxide and oxygen molecules throughout the body.
2. Supporting the balance of the internal environment (homeostasis).
3. Transfer of nutritional compounds, vitamins, hormones and minerals.
4. Picking up products metabolic processes from tissues and moving them to the lungs and kidneys for subsequent excretion.
5. Protection of the body from foreign elements (in combination with lymph).
6. Thermoregulation – blood controls body temperature.
7. Mechanical – creation of turgor tension due to the flow of blood to the organs.

Types of Blood Cells

The following main types of blood cells are distinguished:

1. Red blood cells

Red blood cells have a biconcave shape and an elastic membrane. These features, as well as the lack of a core, allow them to easily pass through small vessels(capillaries), the lumen of which is narrower than the diameter of the cell itself.

The formation of red blood cells in the bone marrow occurs quite slowly; after certain stages, reticulocytes (immature cells) first appear, having remnants of the nucleus and a small amount of hemoglobin. After 2 days they mature into full-fledged red cells. In the fetus, red blood cells begin to form from the 4th week in the liver and spleen, and some time before the birth of the child, this function passes to the bone marrow.

Red blood cells have a lifespan of 110 to 120 days, after which they are removed from the bloodstream as they pass through the spleen, liver, and bone marrow.

2. Leukocytes

Leukocytes are white blood cells with a nucleus.

They protect the body from harmful viruses and bacteria. The blood contains much less of them than red blood cells (from 4 to 10 thousand per 1 microliter). Leukocytes may contain granules, depending on the presence or absence of which they are divided into granulocytes and agranulocytes.

These cells are very actively involved in various processes in the body, and the granules contain a large number of enzymes.

The quantitative content of leukocytes in the blood is expressed as a percentage, since the absolute digital designation is not indicative. The ratio of different types of white cells is called the leukocyte formula.

Granulocytes are divided into:

• Neutrophils - among all leukocytes, they make up the majority. Their nuclei include from 2 to 5 segments. In the peripheral bloodstream, these cells live for about 7 hours, after which they rush into the tissues to perform a protective function.
• Eosinophilic - occupy about 4% of the total number of leukocytes. Their core consists of 2 segments. The granules of these cells include the main protein and peroxidase, which are involved in the release of histamine from the structures of basophils, that is, they take part in the formation of an allergic response.
• Basophils - they occupy about 1% of the total composition of white blood cells. They have specific granules that contain histamine, chondroitin sulfate, and heparin. The release of heparin initiates a cascade during the development of an allergic response.

Agranulocytes are divided into:

• Lymphocytes - they are needed to protect the body from viruses, tumor cells, and autoimmune agents. There are T and B lymphocytes. The former are responsible for cellular immunity and serve as transmitters in the immune response system. The latter are needed for the synthesis of antibodies against pathogens various diseases. All lymphocytes have memory, so if they encounter the microbe again, they begin to fight it faster.
• Monocytes are the largest blood cells, making up about 8% of the total number of white blood cells. Their life time in the bloodstream is no more than 12 hours, after which they turn into macrophages in the tissues. The main purpose of these cells is to resist any foreign agents.

3.Platelets

In another way, these particles are called blood platelets; they are the smallest elements of blood. These cells are disc-shaped and have no nuclei. In healthy people, the number of platelets in the bloodstream ranges from 150 to 450 thousand per 1 microliter. The lifespan of blood platelets is 9–12 days, during which they do not change in any way, but their population is continuously renewed, and the excess is utilized by the spleen.

Platelets are fragments of a large red bone marrow cell - a megakaryocyte. They perform their functions in regulating the process of hemocoagulation (blood clotting) due to special factors contained in alpha granules. These cells are also involved in stopping bleeding (hemostasis). If a blood vessel is damaged, a formation gradually forms at the site of the rupture. blood clot, then a crust forms and the bleeding stops. Without platelet recruitment, any small wound or nosebleed, for example, can cause large blood loss.

Plasma composition and functions

Plasma is a solution consisting of 90% water, and the dry residue includes inorganic and organic compounds. The plasma pH value (acidity level) is a fairly stable value and is equal to 7.36 in arterial blood and 7.4 in venous blood. In the body of an adult, approximately 2.8 to 3.5 liters of plasma circulates, which is about 5% of the total body weight.

The composition of blood plasma is quite rich. Some elements of plasma are unique to blood and are not found in any other environment or tissue of the body. The liquid part of blood includes the following inorganic compounds:

1. Sodium - its amount ranges from 138 to 142 mmol/l. This element is the main cation of fluid outside cells, it is necessary to maintain pH levels and constant volume, as well as to regulate osmotic pressure.
2. Potassium - plasma contains from 3.8 to 5.1 mmol/l. It serves to activate large quantity enzymes are the main elements of fluid inside cells and maintain the excitability of muscles and nerve fibers at the desired level.
3. Calcium - its concentration ranges from 2.26 to 2.75 mmol/l. This element is needed to form bone tissue, transmission of neuromuscular excitation and muscle contraction, as well as to ensure blood clotting and heart function.
4. Magnesium – normally it should be from 0.7 to 1.3 mmol/l. It is involved in inhibition processes in the nervous system and activates some enzymes.
5. Chlorides – their amount is 97 – 106 mmol/l. In combination with sodium, they are needed to stabilize plasma osmolarity, maintain a stable volume and pH level. In addition, chlorine ions play a vital role in the digestion of food in the stomach.
6. Bicarbonate - its concentration ranges from 24 to 35 mmol/l. It is involved in the transfer of carbon dioxide molecules and maintaining blood pH, which makes it possible for many enzymes to work actively.
7. Phosphorus – normal amount from 0.7 to 1.6 mmol/l. It is needed to maintain normal pH and bone tissue formation.

Organic plasma components

The first place among all compounds is occupied by proteins, or, in other words, blood plasma proteins. Their quantity ranges from 60 to 80 g/l, that is, the entire volume of plasma contains about 200 g.

There are three types of proteins:

1. Albumin - normally in the blood of an adult, their concentration should be 40 g/l.
2. Globulins are in turn divided into alpha, beta and gamma globulins. In total, there should be 26 g/l in the blood plasma, while approximately 15 g/l are immunoglobulins (gamma-series compounds), which protect the body from the influence of viruses and bacteria.
3. Fibrinogen - its amount is 4 g/l.

The functions of blood plasma proteins are as follows:

• maintaining a constant volume of blood fluid;
• movement of enzymes, various metabolic products and other organic compounds to various points in the body, for example, from the brain to the heart, or from the liver to the kidneys;
• pH level regulation (so-called protein buffer);
• protecting the body from tumor cells, bacteria and viruses, as well as from its own antibodies (forming tolerance to its cells);
• participation in the process of blood clotting (the ability to form clots and close gaps in blood vessels) and maintaining it in a liquid state.

Plasma organic substances also include:

1. Nitrogen compounds - amino acids, ammonia, urea, transformation products of purine and pyrimidine bases, creatinine.
2. Nitrogen-free substances - glucose, fatty acid, phospholipids, lactate, pyruvate, cholesterol, triacylglycerols.
3. Biologically active compounds – vitamins, mediators, hormones, enzymes.

In addition, blood plasma contains gases - oxygen and carbon dioxide.

Blood plasma facilitates the transfer of any organic substances “from point A to point B,” that is, from the point of their penetration into the body to the place where they carry out their tasks. For example, glucose ( essential substance- a source of energy) from the site of absorption in the intestine, with the help of plasma, is delivered to the cells in the brain. Or vitamin D, which begins to form in the skin, and thanks to the blood is transported to the bones.