Morphology of the blood system and its age-related features. Age-related characteristics of the amount of blood, plasma composition, physico-chemical properties of blood Age-related characteristics of blood briefly

The process of intrauterine hematopoiesis includes 3 stages:

1. Yolk stage. Starts from the 3rd week and continues until the 9th week. Hematopoiesis occurs in the vessels of the yolk sac (primitive primary erythroblasts (megaloblasts) containing HbP are formed from stem cells.

2. Hepatic (hepato-lienal) stage. Starts from the 6th week and continues almost until birth. Initially, both megaloblastic and normoblastic erythropoiesis occur in the liver, and from the 7th month only normoblastic erythropoiesis occurs. Along with this, granulocyto-, megakaryocyto-, monocyto- and lymphocytopoiesis occurs. From the 11th week to the 7th month, erythrocyte-, granulocyto-, monocyto- and lymphocytopoiesis occurs in the spleen.

3. Bone marrow(medullary) stage. It begins at the end of the 3rd month and continues into postnatal ontogenesis. In the bone marrow of all bones (starting from the clavicle), normoblastic erythropoiesis, granulocyto-, monocyto-, megakaryocytopoiesis and lymphopoiesis occur from stem cells. The role of the organs of lymphopoiesis during this period is performed by the spleen, thymus, lymph nodes, palatine tonsils and Peyer's patches.

In children, with age, there is a gradual decrease in myeloid tissue in the bone marrow and functional lability of the hematopoietic apparatus is revealed. The possibility of returning to the megaloblastic type of hematopoiesis remains.

Blood quantity. Newborns and infants have a higher relative amount of blood (15% and 14% of body weight, respectively). A decrease in the value of this indicator to the level of adults occurs by 6–9 years. There is a slight increase in the amount of blood during puberty. With aging, the relative blood mass decreases (up to 67 ml/l).

Relatively high hematocrit(0.54) in newborns decreases to the level of adults by the end of the 1st month, after which it decreases to 0.35 in infancy and childhood (at 5 years - 0.37, at 11-15 years - 0.39) , after which its value increases and by the end of puberty the hematocrit reaches the level of adults (0.40 - 0.45).

Children have relatively high blood levels lactic acid(2.0 - 2.4 mmol/l), which is a reflection of increased glycolysis. In an infant, its level is 30% higher than in adults. With age, its amount decreases (at the age of 1 year - 1.3 - 1.8 mmol/l).

In newborns, content proteins in the blood is 48 - 56 g/l. Their number increases to the level of adults by 3–4 years. Young children are characterized by individual fluctuations in the amount of proteins in the blood. The relatively low protein level is due to insufficient liver function (protein-forming). During ontogenesis, the A/G ratio changes. In the first days after birth, there are more globulins in the blood, especially g-globulins (from the mother's plasma). They then quickly collapse. In the first months, the albumin content is reduced (37 g/l). It gradually increases and by 6 months reaches 40 g/l, and by 3 years it reaches adult levels. The high content of g-globulins at the time of birth is explained by their ability to pass through the placental barrier. With old age, there is a slight decrease in protein concentration and protein coefficient due to a decrease in albumin content and an increase in the amount of globulins.

Low level proteins in the blood of newborns causes lower oncotic blood pressure compared to adults.

In newborns pH and blood buffer bases are reduced (decompensated acidosis on the 1st day, and then compensated acidosis). With old age, the amount of buffer bases decreases (especially blood bicarbonates).

Relative density blood levels in newborns are higher (1.060-1.080) than in adults. Then the established relative blood density during the first months remains at the level of adults.

Viscosity blood levels in newborns are relatively high (10.0-14.8), which is 2-3 times higher than in adults (mainly due to an increase in the number of red blood cells). By the end of the 1st month, viscosity decreases and remains at a relatively constant level, without changing with old age.

Erythropoiesis. The number of red blood cells in the fetus gradually increases, and there is a decrease in their diameter, volume and number of nucleated cells. In newborns, the intensity of erythropoiesis is approximately 5 times higher than in adults. The number of red blood cells in them on the 1st day is increased compared to adults and reaches 6-10 x10 12 / l. On the 2-3rd day their quantity decreases as a result of their destruction (physiological jaundice) and during the 1st month their content decreases to 4.7x10 12 / l. In this case, anisocytosis, poikilocytosis and polychromatophilia are detected, and sometimes nucleated red blood cells are also found. During the first half of the year, infants are characterized by a further decrease in the number of red blood cells, after which their number increases to 4.2x10 12 /l. Starting from the age of 4, there is a decrease in myeloid tissue and during puberty, hematopoiesis is preserved in the red bone marrow of the spongy substance of the vertebral bodies, ribs, sternum, leg bones and femurs. With aging, there is a decrease in the total mass of red bone marrow and its proliferative activity. There is a tendency towards a decrease in the number of red blood cells and hemoglobin.

Hemoglobin. The function of an oxygen carrier in an embryo up to 9-12 weeks is performed by the embryonic (primitive) hemoglobin(HbP), which is replaced by fetal hemoglobin (HbF) by the 3rd month of intrauterine development. At the 4th month, adult hemoglobin (HbA) appears in the fetal blood and its amount does not exceed 10% until 8 months. Newborns still retain up to 70% HbF and already contain 30% HbA. The amount of Hb is increased (170 - 246 g/l), but, starting from the 1st day, its content gradually decreases. In elderly and senile people, the Hb content decreases slightly and fluctuates within the lower limit of the norm for mature age.

ESR in newborns it is lower than in adults and equals 1-2 mm/h.

Leukocytes. In newborns, immediately after birth, the number of leukocytes is increased and reaches 15 x 10 12 / l (leukocytosis of newborns). After 6 hours, their quantity increases to 20 x10 12 /l, after 24 hours - 28 x10 12 /l, 48 hours - 19 x10 12 /l. The regeneration index is increased and a shift in the leukocyte formula to the left is noted. The highest increase in the number of leukocytes is observed on the 2nd day. Then their number decreases and the maximum drop in the curve occurs on the 5th day, and by the 7th day their number approaches the upper limit of the adult norm. In infants, there is a relatively low motor and phagocytic activity of leukocytes. The picture of white blood in children after the 1st year of life is characterized by a gradual decrease in the absolute number of leukocytes, an increase in the relative number of neutrophils with a corresponding decrease in the number of lymphocytes. In the leukocyte formula, 2 “crossovers” of changes in leukocytes are noted. First- at the age of 3 - 7 days (decrease in the percentage of neutrophils and increase in the percentage of lymphocytes) and second- at the age of 4-6 years (increasing percentage of neutrophils and decreasing percentage of lymphocytes). With old age, leukopenia (leukopenia of old age) and eosinopenia are noted. The functional reserve of leukopoiesis decreases under extreme conditions.

Platelets. The number of platelets in newborns in the first hours after birth ranges from 150 to 320 x 10 9 /l, which on average does not differ significantly from their content in the blood of adults. This is followed by a slight decrease in their quantity (up to 164-178x10 9 /l) by 7-9 days, after which by the end of the 2nd week their content increases and remains practically without significant changes at the level of adults. Children 1 day of life are characterized by a large number of round and young forms of platelets, the number of which decreases with age.

Hemostasis. There is no fibrinogen, prothrombin and accelerin in the blood of the fetus until 16 - 20 weeks, and therefore it does not clot. Fibrinogen appears at 4-5 months of intrauterine life, its concentration is 0.6 g/l. During this period, the activity of the fibrin-stabilizing factor is still low, but the activity of heparin is high (almost 2 times higher than in adults). The low level of factors of the coagulation and anticoagulation systems of the blood in the fetus is explained by the immaturity of the cellular structures of the liver that carry out their biosynthesis. In the blood of newborns, there is a low concentration of a number of factors (FII, FVII, FIX, FX, FXI, FXIII) of the blood coagulation system, anticoagulants and plasminogen, although the ratio of their concentrations is the same as in adults. In children in the first days of life, blood clotting time is reduced, especially on the 2nd day, after which it gradually increases and reaches the blood clotting rate in adults by the end of adolescence. During childhood, there is a gradual increase in the content of procoagulants and anticoagulants. In this case, heterochronic maturation of individual links (pro- and anticoagulants) in a given postnatal period is characteristic. By the age of 14-16 years, the content and activity of all factors involved in blood coagulation and fibrinolysis reach adult levels.

Blood groups. The formation of factors that determine group membership in ontogeny does not occur simultaneously. Agglutinogens A and B are formed by 2-3 months of the antenatal period, and agglutinins a and b - by the time of or after birth, which determines the low ability of erythrocytes to agglutinate, which reaches its level in adults by 10-20 years.

Agglutinogens of the Rh system appear in the fetus at 2 - 3 months, while the activity of the Rh antigen in the prenatal period is higher than in adults.

Blood carries out transport function- transfer of nutrients from the digestive organs to the cells and tissues of the body and removal of decay products. During the process of metabolism, substances are constantly formed in cells that can no longer be used for the needs of the body, and often turn out to be harmful to it. From the cells, these substances enter the tissue fluid and then into the blood. These products are delivered by blood to the kidneys, sweat glands, lungs and excreted from the body.

Blood performs protective function. Toxic substances or microbes may enter the body. They are destroyed and destroyed by certain blood cells or glued together and rendered harmless by special protective substances.

Blood participates in the humoral regulation of the body’s activities, performs thermoregulatory function, cooling energy-consuming organs and warming organs that lose heat.

6.1. Quantity and composition of blood.

The amount of blood in the body changes with age.

Blood is an opaque, red liquid containing many tiny blood cells. Formed elements that determine the possibility of performing one of the blood functions - respiratory - red blood cells(red blood cells). The respiratory function of red blood cells is associated with the presence of a special substance in them - hemoglobin. Leukocytes- white blood cells, the most important function of which is protection against microorganisms and toxins entering the blood (phagocytosis). Based on their shape, structure and functions, the main types of leukocytes are distinguished: lymphocytes, monocytes, neutrophils. Lymphocytes are formed mainly in the lymph nodes. They are not capable of phagocytosis, but by producing antibodies, they play an important role in providing immunity. Neutrophils are produced in the red bone marrow: they are the most numerous leukocytes and play a major role in phagocytosis. Monocytes- cells formed in the spleen and liver. Platelets- the smallest of the formed elements of blood. The main function of platelets is associated with their participation in blood clotting.

Age-related features of blood composition.

Characteristic of newborns, a very large number of red blood cells makes the blood thicker (viscous). In the blood of newborns, the number of red blood cells can exceed 7 million per 1 mm3; the blood of newborns is characterized by a high content of hemoglobin. By the 5th - 6th day of life, these indicators decrease. Then, by the age of 3 - 4 years, the number of hemoglobin and red blood cells increases slightly; at 6 - 7 years, there is a slowdown in the increase in the number of red blood cells and the hemoglobin content; from the age of 8, the number of red blood cells and the amount of hemoglobin increase again.

The number of leukocytes in a newborn can be very different, but, as a rule, it increases during the first day of life to 15 - 30 thousand per 1 mm?, and then begins to decrease. By the 7th - 12th day it reaches 10 - 12 thousand. This number of leukocytes remains in children of the first year of life, after which it decreases and by 13 - 15 years it reaches the values ​​of an adult. The younger the child is, the more immature forms of leukocytes his blood contains.

In the first years of a child’s life, the percentage of leukocytes is characterized by an increased content of lymphocytes and a decreased number of neutrophils. By 5-6 years, the number of these formed elements levels off, after which the percentage of neutrophils steadily increases, and the percentage of lymphocytes decreases. The low content of neutrophils, as well as their insufficient maturity, partly explains the greater susceptibility of young children to infectious diseases.

Blood clotting in children in the first days after birth is slow, this is especially noticeable on the 2nd day of the child’s life. From the 3rd to the 7th day, blood clotting accelerates and approaches the adult norm. In children of preschool and school age, blood clotting time has wide individual variations. On average, the beginning of coagulation in a drop of blood occurs after 1 - 2 minutes, the end of coagulation - after 3 - 4 minutes.

7.1. general characteristics blood Blood, lymph and tissue fluid are the internal environment of the body in which the vital activity of cells, tissues and organs takes place. The internal environment of a person maintains a relative constancy of its composition, which ensures the stability of all functions of the body and is the result of reflex and neurohumoral self-regulation. Blood, circulating in blood vessels, performs a number of vital functions: transport (transports oxygen, nutrients, hormones, enzymes, and also delivers residual metabolic products to the excretory organs), regulatory (maintains relative constancy of body temperature), protective (blood cells provide immune response reactions). Amount of blood. Deposited and circulating blood. The amount of blood in an adult is on average 7% of body weight, in newborns - from 10 to 20% of body weight, in infants - from 9 to 13%, in children from 6 to 16 years old - 7%. How younger child, the higher his metabolism and the greater the amount of blood per 1 kg of body weight. Newborns have 150 cubic meters per 1 kg of body weight. cm of blood, in infants - 110 cubic meters. cm, for children from 7 to 12 years old - 70 cubic meters. cm, from 15 years old - 65 cubic meters. cm. The amount of blood in boys and men is relatively greater than in girls and women. At rest, approximately 40–45% of the blood circulates in the blood vessels, and the rest is in the depot (capillaries of the liver, spleen and subcutaneous tissue). Blood from the depot enters the general bloodstream when body temperature rises, muscle work, rise to altitude, and blood loss. Rapid loss of circulating blood is life-threatening. For example, with arterial bleeding and loss of 1/3-1/2 of the total amount of blood, death occurs due to a sharp drop in blood pressure. Blood plasma. Plasma is the liquid part of the blood after all the formed elements have been separated. In adults it accounts for 55–60% of the total blood volume, in newborns it is less than 50% due to the large volume of red blood cells. The blood plasma of an adult contains 90–91% water, 6.6–8.2% proteins, of which 4–4.5% albumin, 2.8–3.1% globulin and 0.1–0.4% fibrinogen; the rest of the plasma consists of minerals, sugar, metabolic products, enzymes, and hormones. The protein content in the plasma of newborns is 5.5–6.5%, in children under 7 years of age – 6–7%. With age, the amount of albumin decreases and globulin increases, the total protein content approaches the level of adults by 3–4 years. Gamma globulins reach the adult norm by 3 years, alpha and beta globulins by 7 years. The content of proteolytic enzymes in the blood after birth increases and by the 30th day of life reaches the level of adults. Mineral substances in the blood include table salt (NaCl), 0.85-0.9%, potassium chloride (KC1), calcium chloride (CaC12) and bicarbonates (NaHCO3), 0.02% each, etc. In newborns, the amount of sodium is less than in adults, and reaches normal by 7–8 years. From 6 to 18 years of age, sodium content ranges from 170 to 220 mg%. The amount of potassium, on the contrary, is highest in newborns, lowest at 4–6 years of age and reaches the adult norm by 13–19 years. The calcium content in plasma in newborns is higher than in adults; from 1 to 6 years it fluctuates, and from 6 to 18 years it stabilizes at the level of adults. Boys 7-16 years old have 1.3 times more inorganic phosphorus than adults; organic phosphorus is 1.5 times more than inorganic phosphorus, but less than in adults. The amount of glucose in the blood of an adult on an empty stomach is 0.1–0.12%. The amount of blood sugar in children (mg%) on an empty stomach: in newborns – 45–70; for children 7-11 years old – 70–80; 12–14 years old – 90-120. The change in blood sugar levels in children aged 7–8 years is significantly greater than in children aged 17–18 years. Significant fluctuations in blood sugar levels occur during puberty. With intense muscular work, the blood sugar level decreases. In addition, the blood plasma contains various nitrogenous substances, amounting to 20–40 mg per 100 cubic meters. cm blood; 0.5–1.0% fat and fat-like substances. The viscosity of the blood of an adult is 4–5, of a newborn – 10–11, of a child in the first month of life – 6, then a gradual decrease in viscosity is observed. The active blood reaction, depending on the concentration of hydrogen and hydroxyl ions, is slightly alkaline. The average blood pH is 7.35. When acids formed during metabolism enter the blood, they are neutralized by a reserve of alkalis. Some acids are removed from the body, for example, carbon dioxide is converted into carbon dioxide and water vapor, exhaled during increased ventilation of the lungs. When there is excessive accumulation of alkaline ions in the body, for example during a vegetarian diet, they are neutralized by carbonic acid, which is retained when ventilation of the lungs decreases.

7.2. Formed elements of blood The formed elements of blood include erythrocytes, leukocytes and platelets. Erythrocytes are non-nucleated red blood cells. They have a biconcave shape, which increases their surface by approximately 1.5 times. The number of red blood cells in 1 cubic meter. mm of blood is equal to: in men – 5–5.5 million; in women - 4–5.5 million. In newborns on the first day of life, their number reaches 6 million, then a decrease occurs to the adult norm. At 7–9 years old, the number of erythrocytes is 5–6 million. The greatest fluctuations in the number of erythrocytes are observed during puberty. In the erythrocytes of an adult, hemoglobin makes up about 32% of the weight of the formed elements and an average of 14% of the weight of whole blood (14 g per 100 g blood). This amount of hemoglobin is equal to 100%. The hemoglobin content in the red blood cells of newborns reaches 14.5% of the adult norm, which is 17–25 g of hemoglobin per 100 g of blood. In the first two years, the amount of hemoglobin drops to 80–90%, and then rises again to normal. The relative content of hemoglobin increases with age and by 14–15 years it reaches the adult norm. It is equal (in grams per 1 kg of body weight) at 7–9 years – 7.5; 10–11 years – 7.4; 12–13 years – 8.4; 14–15 years – 10.4. Hemoglobin has species specificity. If in a newborn it absorbs more oxygen than in an adult (and from the age of 2 this ability of hemoglobin is maximum), then from the age of 3 hemoglobin absorbs oxygen in the same way as in adults. The significant content of red blood cells and hemoglobin, as well as the greater ability of hemoglobin to absorb oxygen in children under 1 year of age, provide them with a more intense metabolism. With age, the amount of oxygen in arterial and venous blood increases. 0 but equals (in cubic cm per minute): in children 5–6 years old in arterial blood - 400, in venous blood - 260; in adolescents 14–15 years old – 660 and 435, respectively; in adults – 800 and 540, respectively. The oxygen content in arterial blood (in cubic cm per 1 kg of weight per minute) is equal to: in children 5–6 years old – 20; in adolescents 14–15 years old – 13; in adults - 11. This phenomenon in preschoolers is explained by the relatively large amount of blood and blood flow, significantly exceeding the blood flow of adults. In addition to oxygen transfer, red blood cells participate in enzymatic processes, in maintaining an active blood reaction and in the exchange of water and salts. During the day, from 300 to 2000 cubic meters pass through red blood cells. dm of water. During the process of settling whole blood, to which substances that prevent blood clotting have been added, red blood cells gradually settle. The rate of erythrocyte sedimentation reaction (ESR) in men is 3–9 mm, in women – 7–12 mm per hour. S0E depends on the amount of proteins in the blood plasma and on the ratio of globulins to albumins. Since a newborn’s plasma contains about 6% proteins and the ratio of globulins to albumins is also less than in adults, their ESR is about 2 mm, in infants – 4–8 mm, and in older children – 4–8 mm at one o'clock. After an educational load, in most children 7-11 years old, normal (up to 12 mm per hour) and slow ESR accelerate, and accelerated ESR slows down. Hemolysis. Red blood cells are able to survive only in physiological solutions, in which the concentration of minerals, especially table salt, is the same as in blood plasma. In solutions where the sodium content is less or more than in the blood plasma, as well as under the influence of other factors, red blood cells are destroyed. The destruction of red blood cells is called hemolysis. The ability of red blood cells to resist hemolysis is called resistance. With age, the resistance of erythrocytes decreases significantly: the erythrocytes of newborns have the greatest resistance, by the age of 10 it decreases by about 1.5 times. In a healthy body, there is a constant process of destruction of erythrocytes, which is carried out under the influence of special substances - hemolysins produced in the liver. Red blood cells live for 14 days in a newborn, and no more than 100–150 days in an adult. Hemolysis occurs in the spleen and liver. Simultaneously with hemolysis, new red blood cells are formed, so the number of red blood cells is maintained at a relatively constant level. Blood groups. Depending on the content of two types of adhesive substances (agglutinogens A and B) in erythrocytes, and two types of agglutinins (alpha and beta) in plasma, four blood groups are distinguished. When transfusing blood, it is necessary to avoid matching A with alpha and B with beta, because agglutination occurs, leading to blockage of blood vessels and preceding hemolysis in the recipient, and therefore leading to his death. Red blood cells of the first group (0) are not glued together by the plasma of other groups, which allows them to be administered to all people. People with the first blood group are called universal donors. Plasma of the fourth group (AB) does not glue red blood cells of other groups, so people with this blood group are universal recipients. Blood of the second group (A) can be transfused only to groups A and AB, blood of group B - only B and AB. Blood type is determined genetically. In addition, in the practice of blood transfusion, the agglutinogen Rh factor (Rh) is of particular importance. The red blood cells of 85% of people contain the Rh factor (Rh positive), while the red blood cells of 15% of people do not contain it (Rh negative). Leukocytes. These are colorless nucleated blood cells. In an adult, 1 cu. mm of blood contains 6–8 thousand leukocytes. Based on the shape of the cell and nucleus, leukocytes are divided into: neutrophils; basophils; eosinophils; lymphocytes; monocytes. Unlike adults, newborns have 1 cubic meter. mm of blood contains 10–30 thousand leukocytes. The largest number of leukocytes is observed in children aged 2–3 months, and then it gradually decreases in waves and reaches the level of adults by 10–11 years.

In children under 9-10 years of age, the relative content of neutrophils is significantly lower than in adults, and the number of lymphocytes increases sharply until 14-15 years of age. Up to 4 years, the absolute number of lymphocytes exceeds the number of neutrophils by approximately 1.5–2 times; from 4 to 6 years, the number of neutrophils and lymphocytes is first compared, and then neutrophils begin to predominate over lymphocytes, and from the age of 15 their ratio approaches adult norms. Leukocytes live up to 12–15 days. Unlike erythrocytes, the content of leukocytes fluctuates greatly. A distinction is made between an increase in the total number of leukocytes (leukocytosis) and a decrease (leukopenia). Leukocytosis is observed in healthy people during muscular work, in the first 2–3 hours after eating and in pregnant women. A person lying down has twice as much leukocytosis as a person standing. Leukopenia occurs when exposed to ionizing radiation. Some diseases change the relative abundance of different forms of white blood cells. Platelets. These are the smallest nuclear-free plates of protoplasm. In adults, 1 cu. mm of blood contains 200–100 thousand platelets, in children under 1 year old – 160–330 thousand; from 3 to 4 years – 350–370 thousand. Platelets live 4–5 and no more than 8–9 days. The dry residue of platelets contains 16–19% lipids (mainly phosphatides), proteolytic enzymes, serotonin, blood clotting factors and retractin. An increase in the number of platelets is called thrombocytosis, a decrease is called thrombopenia.

7.3. Circulation Blood is able to perform vital functions only when it is in constant motion. The movement of blood in the body, its circulation constitute the essence of blood circulation. The circulatory system maintains the constancy of the internal environment of the body. Thanks to blood circulation, oxygen, nutrients, salts, hormones, water are supplied to all organs and tissues and metabolic products are removed from the body. Due to the low thermal conductivity of tissues, heat transfer from organs human body(liver, muscles, etc.) to the skin and in environment carried out mainly due to blood circulation. The activity of all organs and the body as a whole is closely related to the function of the circulatory organs. Large and small circles of blood circulation. Blood circulation is ensured by the activity of the heart and blood vessels. The vascular system consists of two circles of blood circulation: large and small. The large circle of blood circulation begins from the left ventricle of the heart, from where blood enters the aorta. From the aorta, the path of arterial blood continues through the arteries, which branch as they move away from the heart, and the smallest of them break up into capillaries, which permeate the entire body in a dense network. Through the thin walls of the capillaries, the blood releases nutrients and oxygen into the tissue fluid. In this case, the waste products of the cells enter the blood from the tissue fluid. From the capillaries, blood flows into small veins, which, merging, form larger veins and flow into the superior and inferior vena cava. The superior and inferior vena cava bring venous blood to the right atrium, where the systemic circulation ends. The pulmonary circulation begins from the right ventricle of the heart with the pulmonary artery. Venous blood is carried through the pulmonary artery to the capillaries of the lungs. In the lungs, gases are exchanged between the venous blood of the capillaries and the air in the alveoli of the lungs. From the lungs, through four pulmonary veins, arterial blood returns to the left atrium, where the pulmonary circulation ends. From the left atrium, blood enters the left ventricle, where the systemic circulation begins.

.1.3. Age characteristics blood In newborns and children, the hemogram and leukocyte formula differ from those of adults. Hemogram of newborns: 1) red blood cells 6–7 1012/l (erythrocytosis); 2) leukocytes 10–30 109/l (leukocytosis); 3) platelets 200–300 109/l, i.e., as in adults. After 2 weeks, the erythrocyte content approaches the levels of adults (about 5.0 1012/l). After 3–6 months, the number of erythrocytes decreases (less than 4–5 1012/l) - physiological anemia, and then gradually reaches the levels in adults during puberty. The content of leukocytes in children 2 weeks after birth decreases to 9-15 109/l and by the time of puberty reaches the level in adults. Leukocyte formula of newborns. The greatest changes in the leukocyte formula are observed in the content of neutrophils and lymphocytes. The remaining indicators do not differ significantly from those in adults (Table 5.1).

Table 5.1. Leukocyte formula5.2. hematopoiesis

Hematopoiesis(hemocytopoiesis) is the process of formation of blood cells. There are two types of hematopoiesis: myeloid and lymphoid. In turn, in myeloid hematopoiesis there are: a) erythrocytopoiesis; b) granulocytopoiesis; c) thrombocytopoiesis; d) monocytopoiesis, and in lymphoid: a) T-lymphocytopoiesis; b) B-lymphocytopoiesis; c) NK cytopoiesis. In addition, hemocytopoiesis is divided into two periods: embryonic and postembryonic. In the embryonic period of hemocytopoiesis, the formation of blood as tissue occurs, therefore it represents the histogenesis of blood. Postembryonic hemocytopoiesis is a process of physiological blood regeneration. The embryonic period of hemocytopoiesis occurs in embryogenesis in stages, replacing different hematopoietic organs. The stages overlap each other, thereby ensuring continuity of the process. In accordance with this, embryonic hemocytopoiesis is divided into three stages: 1) vitelline, 2) hepatothymolenal, 3) medullary (medullolymphoid). Vitelline hematopoiesis begins from the 2-3rd week of embryogenesis: in the mesenchyme of the yolk sac, as a result of proliferation of mesenchymal cells, "blood islands" The peripheral cells of the islets are flattened (vascular endothelium), the central cells are rounded and turn into blood stem cells. Primary erythroblasts, primary erythrocytes (megaloblasts, megalocytes) are formed intravascularly (in the vessels). Extravascularly, granular leukocytes begin to develop in small numbers from some of the stem cells. At the end of the 3rd week, the vitelline vascular network connects with the embryonic one (in the embryonic body), and the vitelline circulatory system is established. Blood and blood stem cells enter the vessels of the embryo, stem cells populate the anlage of future hematopoietic organs. By the 12th week, yolk hematopoiesis stops. The hepatothymolenal stage is characterized by the following:– specific organ localization; – increased quantitative and qualitative parameters of the blood (granulocytopoiesis, thrombocytopoiesis, monocytopoiesis and lymphocytopoiesis appears); – extravascular character; – transition to the normoblastic type of hematopoiesis. In the liver, from the 5th week to the end of the 5th month, it occurs mainly extravascular myeloid hematopoiesis, which gradually decreases and completely stops by birth. From the 7th week, NK cells first appear in the liver, which are detected in the blood only from the 27-28th week. The thymus very quickly (9-12 weeks) from a universal hematopoietic organ becomes lymphoid, T-lymphocytopoiesis begins in it, which continues after birth until its involution (25–30 years). From the 7-8th week, the spleen is populated with stem cells, and universal extravascular hematopoiesis begins in it (myelo- and lymphocytopoiesis), especially active from the 5th to 7th month . From the 7th month, myelopoiesis is suppressed and stops at birth. Lymphoid hematopoiesis is localized around the arterial vessels of the organ, increases and continues in the postnatal period. Medullary stage. From the 2-3rd month, red bone marrow becomes the source of blood stem cells. The anlage of red bone marrow appears in the 2nd month of embryogenesis, hematopoiesis in it begins from the 3rd month, and from the 6-10th month it becomes the main organ of myeloid and partially lymphoid hematopoiesis, i.e., a universal hematopoietic organ. During this period, lymphoid hematopoiesis occurs in the thymus, lymph nodes, and spleen. As a result of the sequential change of hematopoietic organs and the improvement of the hematopoietic process, blood is formed as tissue. The postembryonic period of hemocytopoiesis occurs in the red bone marrow and lymphoid organs (thymus, lymphoid organs, lymph nodes, spleen). The essence of the hematopoietic process lies in the proliferation and step-by-step differentiation of stem cells into mature formed elements of blood. The unipotent theory of hematopoiesis is generally accepted [Maksimov A. A., 1909], according to which all formed elements of blood develop from a single precursor - a stem cell. Hematopoiesis in the postnatal period of ontogenesis is represented primarily by two types of hematopoiesis: myeloid and lymphoid. Each type of hematopoiesis is divided into varieties or series of hematopoiesis (differentons). Myelopoiesis: a) erythrocytopoiesis, or erythrocyte series; b) granulocytopoiesis, or granulocytic series; c) monocytopoiesis, or monocytic series; d) thrombocytopoiesis, or platelet series. Lymphocytopoiesis: a) T-lymphocytopoiesis, or T-lymphocyte series; b) B-lymphocytopoiesis, or plasmacytopoiesis. In the process of step-by-step differentiation of stem cells into mature blood cells, intermediate types of cells are formed in each row of hematopoiesis, which make up cell classes in the hematopoietic scheme. In total, in the hematopoietic scheme, there are different classes of cells: I – hematopoietic stem cells (HSC); II – half-stem; III – unipotent; IV – blast; V – maturing; VI – mature formed elements. Morphological and functional characteristics of cells of various classes of the hematopoiesis scheme. Class I – stem totipotent (pluripotent, pluripotent) cell, capable of maintaining its population. In morphology it corresponds to a small lymphocyte: – has the ability to self-sustain its population without an influx of cells from the outside; – rarely divides. The division of HSCs is stimulated by the stem cell factor produced by the stromal cells of the bone marrow; - capable of forming all types of blood cells; - resistant to damaging factors; - located in places that are well protected from external influences and have an abundant blood supply (bone tissue cells); - circulates in the blood, migrating to other hematopoietic organs. The direction of differentiation of a stem cell is determined by the content of this formed element in the blood, as well as by the influence of the microenvironment of stem cells, the inductive influence of stromal (reticular) cells of the red bone marrow or other hematopoietic organ that produces hematopoietic growth factors (hematopoietins). Maintaining the population of stem cells is ensured by that after mitosis of a stem cell, one of the daughter cells takes the path of differentiation, and the other takes on the morphology of a small lymphocyte and remains a stem cell. Stem cells rarely divide (their interphase is 1–2 years): 80% of stem cells are in a state of rest and only 20% - in mitosis and subsequent differentiation. During the process of proliferation in bone marrow or spleen culture, each stem cell forms a group, or clone, of cells, therefore stem cells in the literature are often called colony-forming units - CFU-C. Class II - semi-stem, limited pluripotent or multipotent (partially committed) cells – precursors of: a) myelopoiesis – CFU-GEMM; b) lymphocytopoiesis - CFU-L, or Lsk; c) NK cytopoiesis. They have the morphology of a small lymphocyte. Each of them produces a clone of cells, but only myeloid or lymphoid. They divide more often (after 3-4 weeks) and also maintain the size of their population. Class III - oligopotent (CFU-GM) and unipotent (progenitor) poetinsensitive cells - the precursors of their hematopoietic series: CFU-M, CFU-Gn, CFU-Eo, CFU-B, CFU-Meg and CFU-E. Their morphology also corresponds to the morphology of a small lymphocyte. They are able to differentiate into only one type of shaped element. They divide frequently, but some descendants of these cells enter the path of differentiation, while others maintain the size of the population of cells of this class. The frequency of division of these cells and the ability to differentiate further depend on the content of special biologically active substances in the blood - poetins , specific for each series of hematopoiesis (erythropoietins, thrombocytopoietins, etc.). The first three classes of cells are combined into a class of morphologically unidentifiable cells, since they all have the morphology of a small lymphocyte, but their development potencies are different. Class IV - blast (young) cells , or blasts (erythroblasts, lymphoblasts, etc.). They differ in morphology from both the three preceding and subsequent classes of cells. These cells are large, have a large loose nucleus rich in euchromatin with 2-4 nucleoli, the cytoplasm is basophilic due to a large number of free ribosomes. They divide frequently, but the daughter cells all embark on the path of further differentiation. Based on their cytochemical properties, blasts of different hematopoietic series can be identified. Class V is a class of maturing (differentiating) cells characteristic of their hematopoietic series. In this class there may be several varieties of transitional cells - from one (prolymphocyte, promonocyte) to five - in the erythrocyte series. Some maturing cells in small quantities (see leukocyte formula of granulocytes) can enter the blood (for example, reticulocytes, young and band granulocytes). Class VI - mature blood cells. It should be noted that only erythrocytes, platelets and segmented granulocytes are mature final differentiated formed elements or their fragments. Monocytes are not terminally differentiated cells. Leaving the bloodstream, they differentiate in tissues into final cells - macrophages. When lymphocytes encounter antigens, they turn into blasts and divide again. The totality of cells that make up the line of differentiation of a stem cell into a certain shaped element forms its differential, or histogenetic series. For example, the erythrocyte differon (erythron) consists of: class I – stem cell (SC); Class II – semi-stem cell (HSC) – precursor of myelopoiesis; Class III - unipotent erythropoietin-sensitive cell - CFU-E, this also includes the burst-forming unit - BFU-E, capable of quickly (explosively) forming a colony of erythroid cells numbering several hundred elements; Class IV – proerythroblast; Class V – maturing cells: basophilic, polychromatophilic, oxyphilic normocyte; Class VI - erythrocyte. In the process of maturation of erythrocytes in class V, the following occurs: a) synthesis and accumulation of hemoglobin, b) reduction of organelles, c) reduction of the nucleus. Normally, the replenishment of erythrocytes occurs mainly due to the division and differentiation of maturing cells - pronormocytes, basophilic and polychromatophilic normocytes. This type of hematopoiesis is called homoplastic hematopoiesis. Each student should be able to list the cellular elements that make up the differons of other formed elements of blood according to the hematopoiesis diagram.5.2.1. Granulocytopoeia There are three types of granulocytes, each of which is derived from its own unipotent stem cell, a derivative of CFU-GEMM (colony-forming unit of granulocytes, erythrocytes, monocytes and megakaryocytes), forming a histologically defined myeloblast. Neutrophil formation: class I (SC) class II (PSC) III class (unipotent leukopoietin-sensitive cell - CFU-Gn) class IV (neutrophil myeloblast) class V (neutrophil promyelocyte, neutrophil myelocyte, neutrophil metamyelocyte, band neutrophil) class VI (mature neutrophil) Neutrophil myeloblast (class IV) with a diameter of 12 to 14 microns, its large round reddish-blue nucleus has a fine network of chromatin, two or three pale gray nucleoli are present, the cytoplasm has no granules; – at the periphery of the cell there are often cytoplasmic protrusions similar to pseudopodia (determined on electron micrographs) – granular endoplasmic material is present in the cytoplasm network, small Golgi complex, many mitochondria and free ribosomes. The neutrophilic promyelocyte (class V) is larger than the myeloblast (diameter 16–24 µm). The nucleus has a rough network of chromatin and 1–2 nucleoli; – the cytoplasm is bluish in color, contains many azurophilic granules (nonspecific), the cell periphery no longer has cytoplasmic protrusions similar to pseudopodia. Electron micrographs show a well-developed Golgi complex, a granular endoplasmic reticulum and many mitochondria; azurophilic granules with a diameter of approximately 0.5 μm form on the surface of the maturing Golgi complex. These are lysosomes containing hydrolytic enzymes and peroxidase. Neutrophilic myelocyte with a diameter of 10–12 µm; has a slightly flattened acentric nucleus with a coarse chromatin network. Nucleoli may or may not be present; - specific granules with a diameter of 0.1 μm, contain lysozyme, alkaline phosphatase, collagenase and phagocytin, are clearly visible, like azurophilic granules - the Golgi complex is well developed, looks like a transparent clean area in the pale blue cytoplasm ;– specific neutrophil granules are formed on the surface of the Golgi complex formation;– cell division is still occurring. This is the only stage at which specific neutrophil granules are formed. The neutrophil metamyelocyte is similar to the neutrophil myelocyte, except that the nucleus is bean-shaped and the rough chromatin network does not have nucleoli (Fig. 5.3); - heterochromatin indicates a decrease in protein synthesis, which is reflected in the reduction organelles in a cell. The band neutrophil is similar to the mature neutrophil except for the horseshoe-shaped nucleus. Band cells are often found in the circulating blood, and in cases of infection of the body, their number increases sharply.

Number of neutrophils produced: In a healthy adult, about 800,000 per day. Formation of Eosinophils and Basophils: The developmental stages of eosinophils and basophils are similar to those described for neutrophils, except that the types of granules formed during the myelocyte stage are specific to each cell type. In addition, the morphology of the nucleus of a mature cell resembles that at the late stage of a band granulocyte. Monocytopoiesis: class I (SC) → class II (PSC) → class III (unipotent cell - CFU-M) - common precursor of monocytes and neutrophils (gives rise to monoblasts) → Class IV (monoblasts) → Class V (promonocyte) → Class VI (monocyte). Promonocyte is a large cell (diameter 16–18 µm) with a somewhat bean-shaped nucleus located eccentrically in a light blue cytoplasm, which also contains many azurophilic granules ( lysosomes) produced by a well-developed Golgi complex, numerous mitochondria and a fairly developed granular endoplasmic reticulum.

The division of promonocytes leads to the formation of monocytes (class VI), which leave the bone marrow, enter the bloodstream, and then, after penetrating the connective tissue of peripheral organs, differentiate into macrophages, as well as dendritic antigen-presenting cells. The number of monocytes formed daily in the body of a healthy adult , is about 1 1010. Formation of blood platelets (thrombocytopoiesis): class I (SC) → class II (PSC) → class III (unipotent thrombopoietin-sensitive cell - CFU-meg) → class IV (megakaryoblast) → class V (promegakaryocyte) → VI class (platelets). Megakaryoblast is a large cell (diameter 25–40 µm), the only large nucleus with notches (or lobulated) has a fine chromatin network. Megakaryoblast division occurs by endomitosis, during which no daughter cells are formed. Instead, the cell acquires gigantic dimensions, the ploidy of the nucleus can reach 64 (see Fig. 5.2); - the cytoplasm is weakly basophilic, without granules, electron micrographs show large mitochondria, numerous polysomes, a certain amount of granular endoplasmic reticulum and a fairly well-developed Golgi complex. Promegakaryocyte – a large round cell with a diameter of 42–45 microns with a voluminous lobulated polyploid nucleus and sharply basophilic cytoplasm; – in addition to the usual organelles, the cytoplasm contains a complex system of smooth vesicles, tubules, flat cisterns, which, merging, form platelet demarcation channels; – in the process of further differentiation promegakaryocytes become either reserve or platelet-producing megakaryocytes. A megakaryocyte is an unusually large cell (diameter 40–100 μm) with one multilobed large polyploid nucleus. Electron micrographs show a well-developed Golgi complex, actively forming α-granules, lysosomes and dense bodies, numerous mitochondria and a fairly developed granular endoplasmic reticulum. Megakaryocytes are located in the circle of sinusoids, into the pores of the walls of which their processes penetrate. The processes disintegrate along certain demarcation channels, forming groups of connected blood platelets, which are then divided into individual platelets. After complete separation of the platelets, the remaining megakaryocytes undergo degeneration, are phagocytosed and replaced by new ones.

5.2.2. Lymphocytopoiesis The precursor cell of lymphocytes originates from the population of SCs (totipotent hematopoietic stem cells), is located in the bone marrow, as well as in the circulating blood, as a member of the population of “zero” cells. These are immunocompetent cells that give rise to at least two populations of SCs: cells - precursors of T-lymphocytes and precursor cells of B-lymphocytes and, probably, precursor cells of NK cells (natural killer cells). There are three stages in T- and B-lymphocytopoiesis: I - bone marrow stage; II – antigen-independent differentiation (in the central immune organs); III – antigen-dependent differentiation (in peripheral organs of immune defense). T-lymphocytopoiesis. Stage I occurs in the lymphoid tissue of the red bone marrow: class I (SC) class II (PSC) - lymphopoiesis precursor cells - CFU-L, or Lsk, class III (unipotent T-poietin-sensitive cells - T-lymphocytopoiesis precursor cells). These cells reach the thymus with the bloodstream./Stage II is carried out in the thymic cortex under the influence of thymosin: unipotent precursor cells (class III) turn into T-lymphoblasts (class IV), then into T-prolymphocytes (class V) and into T -lymphocytes (class VI). In the thymus, three subpopulations of T-lymphocytes develop independently: killers, helpers, suppressors, which acquire different receptors for various antigens. They are carried by the bloodstream into the peripheral lymphoid organs. Stage III occurs in the T-zones of the peripheral lymphoid organs. Under the influence of the corresponding antigen, the T-lymphocyte turns into a T-lymphoblast, or rather a T-immunoblast (blast transformation reaction). Then these cells proliferate and form cell clones: memory T cells, killer T cells, helper T cells, etc., i.e., effector cells that provide cellular immunity. When they encounter an antigen again, memory T lymphocytes of all subpopulations provide a faster and stronger secondary immune response. B-lymphocytopoiesis and plasmacytopoiesis. Stage I is carried out in the red bone marrow, where the following classes of cells are formed: I (SC) → II (PSC) - precursors of lymphopoiesis → Class III - unipotent B-lymphopoietin-sensitive cells - precursors of B-lymphocytopoiesis. Stage II - antigen-independent differentiation - is carried out in birds in a special central lymphoid organ – the bursa of Fabricius. Its analogue in humans has not been precisely established. Most researchers believe that stage II also occurs in the red bone marrow: from unipotent B-cell precursors, B-lymphoblasts (class IV), B-prolymphocytes (class V) and receptor B-lymphocytes (class VI) are formed. At this stage, B-lymphocytes acquire various receptors for antigens - immunoglobulins, which are synthesized in the maturing B-lymphocytes themselves. Stage III - antigen-dependent differentiation - occurs in the B-zones of peripheral lymphoid organs, where the antigen meets the corresponding B-receptor lymphocyte, activation and the transformation of the latter into an immunoblast - plasmablast, and then a clone of cells is formed, among which are distinguished: - memory B lymphocytes; - plasmacytes, which are effector cells of humoral immunity. They synthesize and release immunoglobulins (antibodies) of different classes into the blood or lymph, which form antigen-antibody complexes, neutralizing antigens. Immune complexes are then phagocytosed by neutrophils and macrophages. The blast transformation reaction of a B-lymphocyte requires cooperation between a B-receptor lymphocyte, a macrophage, a T-helper (T-suppressor), and a humoral antigen. The development of NK cells occurs independently of the formation of T- and B- lymphocytes from the bone marrow precursor; – after entering the blood, NK cells circulate in it or migrate to the spleen; – NK cells mature in tissues under the influence of little-studied facts ors of the microenvironment.

29. GENERAL PHYSIOLOGY OF ENDOCRECTION GLANES The highest form of humoral regulation is hormonal. The term "hormone" was first used in 1902 by Starling and Bayliss in relation to the substance they discovered produced in the duodenum - secretin. The term "hormone" is translated from Greek as "stimulating to action", although not all hormones have a stimulating effect. Hormones are biologically high active substances , synthesized and released into the internal environment of the body by the endocrine glands, or endocrine glands, and have a regulatory effect on the functions of organs and systems of the body remote from the place of their secretion. An endocrine gland is an anatomical formation devoid of excretory ducts, the sole or main function of which is the internal secretion of hormones. The endocrine glands include the pituitary gland, pineal gland, thyroid gland, adrenal glands (medulla and cortex), and parathyroid glands. Unlike internal secretion, external secretion is carried out by the exocrine glands through the excretory ducts into the external environment. In some organs both types of secretion are present simultaneously. The endocrine function is carried out by endocrine tissue, i.e. an accumulation of cells with an endocrine function in an organ that has functions not related to the production of hormones. Organs with a mixed type of secretion include the pancreas and gonads. The same endocrine gland can produce hormones that differ in their action. For example, the thyroid gland produces thyroxine and thyrocalcitonin. At the same time, the production of the same hormones can be carried out by different endocrine glands. For example, sex hormones are produced by both the gonads and the adrenal glands. The production of biologically active substances is a function not only of the endocrine glands, but also of other traditionally non-endocrine organs: kidneys, gastrointestinal tract, heart. Not all substances produced by specific cells of these organs meet the classical criteria for the concept of “hormones”. Therefore, along with the term “hormone”, the concepts of hormone-like and biologically active substances (BAS), local hormones have recently also been used. For example, some of them are synthesized so close to their target organs that they can reach them by diffusion without entering the bloodstream. Cells that produce such substances are called paracrine. The difficulty of accurately defining the term “hormone” is especially clearly seen in the example of catecholamines - adrenaline and norepinephrine. When their production in the adrenal medulla is considered, they are usually called hormones; when we are talking about their formation and release by sympathetic endings, they are called mediators. Regulatory hypothalamic hormones - a group of neuropeptides, including the recently discovered enkephalins and endorphins, act not only as hormones, but also perform a kind of mediator function. Some of the regulatory hypothalamic peptides are found not only in neurons of the brain, but also in special cells of other organs, such as the intestine: substance P, neurotensin, somatostatin, cholecystokinin, etc. The cells that produce these peptides form, according to modern concepts, a diffuse neuroendocrine system, consisting of cells scattered throughout different organs and tissues. Cells of this system are characterized by a high amine content, the ability to take up amine precursors, and the presence of amine decarboxylase. Hence the name of the system based on its first letters English words Amine Precursors Uptake and Decarboxylating system - APUD system - a system for capturing amine precursors and their decarboxylation. Therefore, it is legitimate to talk not only about the endocrine glands, but also about the endocrine system, which unites all the glands, tissues and cells of the body that secrete specific regulatory substances into the internal environment. The chemical nature of hormones and biologically active substances is different. The duration of its biological action depends on the complexity of the structure of the hormone, for example, from fractions of a second for mediators and peptides to hours and days for steroid hormones and iodothyronines. Analysis of the chemical structure and physicochemical properties of hormones helps to understand the mechanisms of their action, develop methods for their determination in biological fluids and carry out their synthesis. Classification of hormones and biologically active substances by chemical structure: Amino acid derivatives: tyrosine derivatives: thyroxine, triiodothyronine, dopamine, adrenaline, norepinephrine; tryptophan derivatives: melatonin, serotonin; histidine derivatives: histamine. Protein-peptide hormones: polypeptides: glucagon, corticotropin, melanotropin, vasopressin, oxytocin, peptide hormones of the stomach and intestines; simple proteins (proteins): insulin, somatotropin, prolactin, parathyroid hormone, calcitonin; complex proteins (glycoproteins): thyrotropin, follitropin, lutropin. Steroid hormones: corticosteroids (aldosterone, cortisol, corticosterone); sex hormones: androgens (testosterone), estrogens and progesterone.

Fatty acid derivatives: arachidonic acid and its derivatives: prostaglandins, prostacyclins, thromboxanes, leukotrienes. Despite the fact that hormones have different chemical structures, they share some common biological properties. General properties of hormones: Strict specificity (tropism) of physiological action. High biological activity: hormones exert their physiological effects in extremely small doses. Distant nature of action: target cells are usually located far from the site of hormone production. Many hormones (steroids and amino acid derivatives) are not species specific. Generalization of action. Prolonged action. Four main types of physiological effects on the body have been established: kinetic, or triggering, causing a certain activity of the executive organs; metabolic (metabolic changes); morphogenetic (differentiation of tissues and organs, effect on growth, stimulation of the formation process); corrective (change in intensity of functions of organs and tissues). The hormonal effect is mediated by the following main stages: synthesis and entry into the blood, forms of transport, cellular mechanisms of hormone action. From the site of secretion, hormones are delivered to target organs by circulating fluids: blood, lymph. Hormones circulate in the blood in several forms: 1) in a free state; 2) in combination with specific blood plasma proteins; 3) in the form of a nonspecific complex with plasma proteins; 4) in an adsorbed state on the formed elements of blood. At rest, 80% is a complex with specific proteins. Biological activity is determined by the content of free forms of hormones. Bound forms of hormones are like a depot, a physiological reserve, from which hormones pass into the active free form as needed. A prerequisite for the manifestation of the effects of a hormone is its interaction with receptors. Hormonal receptors are special cell proteins that are characterized by: 1) high affinity for the hormone; 2) high selectivity; 3) limited binding capacity; 4) specificity of receptor localization in tissues. On the same cell membrane there can be dozens of different types receptors. The number of functionally active receptors can change under various conditions and pathologies. For example, during pregnancy, M-cholinergic receptors disappear in the myometrium, and the number of oxytocin receptors increases. In some forms of diabetes mellitus, there is a functional failure of the insular apparatus, i.e. the level of insulin in the blood is high, but some of the insulin receptors are occupied by autoantibodies to these receptors. In 50% of cases, receptors are localized on the membranes of the target cell; 50% is inside the cell. Mechanisms of action of hormones. There are two main mechanisms of action of hormones at the cellular level: the implementation of the effect from the outer surface of the cell membrane and the implementation of the effect after the penetration of the hormone into the cell. In the first case, the receptors are located on the cell membrane. As a result of the interaction of the hormone with the receptor, the membrane enzyme adenylate cyclase is activated. This enzyme promotes the formation from adenosine triphosphate (ATP) of the most important intracellular mediator of hormonal effects - cyclic 3,5-adenosine monophosphate (cAMP). cAMP activates the cellular enzyme protein kinase, which realizes the action of the hormone. It has been established that hormone-dependent adenylate cyclase is a common enzyme that is acted upon by various hormones, while hormone receptors are multiple and specific for each hormone. Secondary messengers, in addition to cAMP, can be cyclic 3,5-guanosine monophosphate (cGMP), calcium ions, and inositol triphosphate. This is how peptide and protein hormones and tyrosine derivatives - catecholamines - act. A characteristic feature of the action of these hormones is the relative speed of the response, which is due to the activation of previous already synthesized enzymes and other proteins. In the second case, receptors for the hormone are located in the cytoplasm of the cell. Hormones of this mechanism of action, due to their lipophilicity, easily penetrate the membrane into the target cell and bind to specific receptor proteins in its cytoplasm. The hormone-receptor complex enters the cell nucleus. In the nucleus, the complex disintegrates, and the hormone interacts with certain sections of nuclear DNA, resulting in the formation of a special messenger RNA. Messenger RNA leaves the nucleus and promotes the synthesis of protein or enzyme protein on ribosomes. This is how steroid hormones and tyrosine derivatives - thyroid hormones - act. Their action is characterized by a deep and long-term restructuring of cellular metabolism.

Inactivation of hormones occurs in effector organs, mainly the liver, where hormones undergo various chemical changes by binding to glucuronic or sulfuric acid or as a result of the action of enzymes. Partially the hormones are excreted unchanged in the urine. The action of some hormones can be blocked due to the secretion of hormones that have an antagonistic effect. Hormones perform the following important functions in the body: Regulation of growth, development and differentiation of tissues and organs, which determines physical, sexual and mental development. Ensuring the body's adaptation to changing living conditions. Ensuring the maintenance of homeostasis. Functional classification of hormones: Effector hormones - hormones that directly affect the target organ. Triple hormones are hormones whose main function is to regulate the synthesis and release of effector hormones. Produced by the adenohypophysis. Releasing hormones are hormones that regulate the synthesis and secretion of adenohypophysis hormones, mainly triple ones. They are secreted by nerve cells of the hypothalamus. Types of hormone interactions. Each hormone does not work alone. Therefore, it is necessary to take into account the possible results of their interaction. Synergism is the unidirectional action of two or more hormones. For example, adrenaline and glucagon activate the breakdown of liver glycogen into glucose and cause an increase in blood sugar levels. Antagonism is always relative. For example, insulin and epinephrine have opposite effects on blood glucose levels. Insulin causes hypoglycemia, adrenaline causes hyperglycemia. The biological significance of these effects boils down to one thing - improving the carbohydrate nutrition of tissues. The permissive effect of hormones is that the hormone, without causing a physiological effect, creates the conditions for a cell or organ to respond to the action of another hormone. For example, glucocorticoids, without affecting vascular muscle tone and the breakdown of liver glycogen, create conditions under which even small concentrations of adrenaline increase blood pressure and cause hyperglycemia as a result of glycogenolysis in the liver. Regulation of the functions of the endocrine glands Regulation of the activity of the endocrine glands is carried out by nervous and humoral factors. The neuroendocrine zones of the hypothalamus, pineal gland, adrenal medulla and other areas of chromaffin tissue are regulated directly by nervous mechanisms. In most cases, the nerve fibers approaching the endocrine glands regulate not the secretory cells, but the tone of the blood vessels, on which the blood supply and functional activity of the glands depend. The main role in the physiological mechanisms of regulation is played by neurohormonal and hormonal mechanisms, as well as direct effects on the endocrine glands of those substances whose concentration is regulated by this hormone. The regulatory influence of the central nervous system on the activity of the endocrine glands is carried out through the hypothalamus. The hypothalamus receives signals from the external and internal environment through the afferent pathways of the brain. Neurosecretory cells of the hypothalamus transform afferent nerve stimuli into humoral factors, producing releasing hormones. Releasing hormones selectively regulate the functions of adenohypophysis cells. Among the releasing hormones, there are liberins - stimulators of the synthesis and release of adenohypophysis hormones and statins - secretion inhibitors. They are called the corresponding tropic hormones: thyrotropin-releasing hormone, corticoliberin, somatoliberin, etc. In turn, tropic hormones of the adenohypophysis regulate the activity of a number of other peripheral endocrine glands (adrenal cortex, thyroid gland, gonads). These are the so-called direct downward regulatory connections. In addition to them, within these systems there are also reverse ascending self-regulating connections. Feedback can come from both the peripheral gland and the pituitary gland. Depending on the direction of physiological action, feedback can be negative and positive. Negative connections self-limit the operation of the system. Positive connections self-start it. Thus, low concentrations of thyroxine through the blood increase the production of thyroid-stimulating hormone by the pituitary gland and thyroid-releasing hormone by the hypothalamus. The hypothalamus is much more sensitive than the pituitary gland to hormonal signals coming from the peripheral endocrine glands. Thanks to the feedback mechanism, a balance is established in the synthesis of hormones, responding to a decrease or increase in the concentration of hormones of the endocrine glands. Some endocrine glands, such as the pancreas and parathyroid glands, are not influenced by pituitary hormones. The activity of these glands depends on the concentration of those substances whose levels are regulated by these hormones. Thus, the level of parathyroid hormone of the parathyroid glands and calcitonin of the thyroid gland is determined by the concentration of calcium ions in the blood. Glucose regulates the production of insulin and glucagon by the pancreas. In addition, the functioning of these glands is carried out due to the influence of the level of antagonist hormones.

Age-related features of the structure and function of the endocrine glands. Part 1. Age-related features of the structure and function of the endocrine glands. Part 1. Age-related features of the pituitary gland. The pituitary gland is of ectodermal origin. The adenohypophysis (together with the intermediate lobe) is formed from the epithelium oral cavity , and the neurohypophysis - from the diencephalon. In children, there is a gap between the anterior and intermediate lobes. In adults, this gap closes and both lobes are closely adjacent to each other. The mass of the pituitary gland in newborns is 100-150 mg. In the second year of life, its increase begins, which turns out to be especially sharp at 4-5 years, after which a period of slow growth of the pituitary gland begins until the age of 11. From the age of 11, his growth rate increases again. By the period of puberty, the mass of the pituitary gland averages 200-350 mg, and by 18-20 years - 500-650 mg. Acidophilic cells of the pituitary gland appear at the 13-15th week of intrauterine development. After the birth of a child, their number increases until the age of 20, remains unchanged from 20 to 50, and then decreases. The function of acidophilic cells begins already during the period of intrauterine development: it was noted in fetuses 50 mm long. The amount of somatotropic hormone secreted by these cells in children under 3-5 years of age is greater than in adults. From 3-5 years of age, the rate of somatotropic hormone secretion characteristic of an adult is established. The amount of somatotropic hormone (GH) released is in accordance with the maturation of the corresponding cells of the hypothalamus. It has been shown that with age, the number of releasing factors that cause the release of somatotropic hormone from the pituitary gland decreases. The sensitivity of various tissues to the action of growth hormone increases with age. This is manifested in an increase in the intensity of cell division, protein and RNA synthesis under the influence of growth hormone. In most cases, growth hormone is released throughout life. The cessation of growth, despite the presence of growth hormone, depends on the increase in the amount of estrogens during puberty, which reduce its activity. Traces of adrenocorticotropic hormone (ACTH) are first detected in the pituitary gland at the 9-10th week of the intrauterine period. The pituitary gland of newborns contains the same amount of ACTH as the pituitary gland of adults. At the same time, the complex of adaptive reactions that develop under the influence of stress factors is either completely absent in newborns or expressed to a very weak degree. This is due to age-related characteristics of the functions of hypothalamic structures. Their sensitivity to impulses that carry information about changes that occur in the internal and external environment of the body increases with age. Accordingly, the influence of the hypothalamic nuclei on the function of the adenohypophysis increases, which under stress conditions is accompanied by an increase in ACTH secretion. In old age, the sensitivity of the hypothalamic nuclei to information coming through the nerve pathways decreases again, which is associated with a less pronounced adaptation syndrome in old age. A decrease in the sensitivity of the hypothalamic nuclei is associated with a decrease in the number of their neurosecretory cells. Thyroid-stimulating hormone (TSH) of the pituitary gland also begins to be released during the prenatal period. However, according to the small number of basophilic cells, its quantity is small. In the first year of life, the number of basophilic cells of the pituitary gland increases and at the same time the amount of TSH secreted increases. The most dramatic increase in TSH secretion is observed immediately after birth and before the onset of puberty. In subsequent years, until the end of puberty, its secretion continues to increase, the maximum of which is reached between the ages of 21 and 30 years. At the age of 51-85 years, its value becomes two times less than at 21-30 years. The antidiuretic hormone of the pituitary gland begins to be released in the fourth month of embryonic development, its maximum release is observed by one year after birth, then the antidiuretic activity of the neurohypophysis begins to fall to fairly low values ​​and at the age of 55 years it is approximately 2 times less than at the age of 1 year. cells associated with the secretion of gonadotropic hormones are characterized by a cyclical nature of their function. Thus, the greatest intensity of secretion is observed in 4-4.5 months of embryonic development, in children - during puberty and in adults - during the period of extinction of sexual function, when the amount of estrogens decreases and, accordingly, their inhibitory effect on the subcutaneous area is removed.

The physiological characteristics of the blood system in different age periods relate to the physicochemical properties of plasma, formed elements (erythrocytes, leukocytes and platelets), the blood coagulation system, hematopoiesis and are determined by the level of development of the morphological and enzymatic structures of the organs of the blood system, as well as neurohumoral mechanisms regulating their activity. In addition, the physiological characteristics of the blood system of newborns are determined by the lack of oxygen in the prenatal period, the influence of maternal blood hormones, trauma during childbirth, cessation of placental circulation and the transition to new conditions of existence.

AGE FEATURES OF COMPOSITION, QUANTITY AND PHYSICAL-CHEMICAL PROPERTIES OF BLOOD

Amount of blood. The amount of blood in a newborn depends on the initial weight and length of the body, on the time of ligation of the umbilical cord. In newborns and infants relative mass There is more blood than in adults (up to 15% of body weight), and only by the age of 6-9 years there is a gradual decrease in its amount to the definitive level (7-8%). During puberty, there is a slight increase in the amount of blood. These age-related changes in the amount of blood are determined by the level of metabolic processes in the body and the need for oxygen supply to organs and tissues. About 60-80% of the total blood volume is in the veins (less at an early age), the rest is in the cavities of the heart, arteries and capillaries. The volume of circulating blood (in ml per 1 kg of body weight) is: in newborns - 110-195, in infants - 75-110, in children of the first childhood - 51-90, in adolescents - 50-92, in adults - 50. Boys have slightly more blood than girls. Depending on individual characteristics, the amount of blood in the body can fluctuate within fairly wide limits.

Physicochemical properties of blood. Blood viscosity, due to the presence of proteins and red blood cells in it, is high in the first days after birth due to the increased number of red blood cells. On the 5-6th day it decreases, reaching by the end of the 1st month of life the viscosity that is established in older children. In schoolchildren, blood viscosity usually becomes higher after an educational load than before it. Prolonged, strenuous physical work also leads to an increase in blood viscosity in children, which can last up to 2 days.

In newborn children, the pH is acidity(7.31) and buffer bases blood (43.5 mmol/l) are reduced, i.e. acidosis is observed (a shift in the acid-base balance to the acidic side), first decompensated, and then compensated. By the end of the 1st week, these indicators begin to exceed the level of adults (7.44 and 47.3 mmol/l), and only by 7-8 years do they begin to correspond to the definitive (adult) values ​​(7.42 and 44.5 mmol/l). l).

Plasma quantity and composition. In newborns, plasma makes up 43-46% of the total blood volume (in an adult 55-60%). By the end of the 1st month of a child’s life, the percentage of plasma content reaches the level of an adult and then, in infancy and childhood up to 15 years, increases to 60-65%. Only at the end of puberty does the relative plasma volume begin to correspond to the definitive level.

Protein composition. The amount of protein in the blood serum of newborns is 47-56 g/l. With age, the amount of protein increases, growing especially rapidly in the first 3-4 years, reaching the level of adults (70-80 g/l). The reduced amount of protein in the blood plasma in children in the first months of life is explained by the insufficient manifestation of the function of the body’s protein-forming systems.

With age, the protein coefficient of the blood also changes - the ratio between albumins and globulins in the blood plasma. At the time of birth, the total globulin content of the child is higher (36%) than that of the mother, and the albumin content is reduced (61%). The high content of gamma globulins at the time of birth is due to the fact that they pass through the placental barrier from the mother. Their amount in the blood gradually decreases, normalizing by 2-3 years (13-14%). The albumin content gradually increases, reaching adult levels by 3 years (63-65%).

Due to the smaller amount of proteins in the plasma, the oncotic pressure of the blood plasma is reduced. These indicators reach adult levels by 3-4 years of age.

Bio chemical composition. The amount of amino acids in the blood of children in the first years of life depends on the type of feeding, but their total amount is 30-35% less than in adults. The following amino acids are determined in plasma: serine, glycine, glutamic acid, arginine, methionine, cysteine ​​and lysine.

The amount of urea and uric acid in the blood serum of children increases from the neonatal period to 2-14 years (2.5-

4.5 mmol/l; 0.14-0.2 mmol/l and 4.3-7.3 mmol/l; 0.17-0.41 mmol/l, respectively).

There is more glycogen in the blood of children (120-210 mg/l) than in adults (70-120 mg/l), and the glucose content is lower. Thus, in the blood serum of a child in the first days of life, the glucose concentration is 1.7-4.2 mmol/l and reaches the level of adults (3.3-5.6 mmol/l) at 12-14 years. Children have increased glycolysis, so the content of lactic acid in their blood is 30% higher than in adults. With age, the content of lactic acid in the blood of children gradually decreases (from 2.0-2.4 in newborns to 1.0-1.7 mmol/l by 14 years).

Enzyme composition. There is no carbonic anhydrase in the fetal blood. There is very little of it in the blood of newborns and its activity is 4-24% of the level of adults. The content of this enzyme, corresponding to the definitive one, is established by the age of 5 years of a child’s life. In the first weeks of a child’s life, the activity of the enzymes amylase, catalase, lipase, and transaminase is slightly reduced. Their activity gradually increases during the 1st year of life. Alkaline phosphatase levels in the blood are elevated throughout childhood, which is associated with the formation and increased growth of bones.

Mineral composition. A detailed description will be given in the chapter “Water-electrolyte metabolism” (Chapter 13).

Introduction

The idea of ​​blood as a system was created by G.F. Lang in 1939. This system included four components: a) peripheral blood circulating through the vessels, b) hematopoietic organs, c) hematopoietic organs, d) the regulatory neurohumoral apparatus.

Blood is one of the most important life support systems of the body, which has a number of features. The high mitotic activity of hematopoietic tissue causes its increased sensitivity to the action of damaging factors, and the genetic determination of the reproduction, differentiation, structure and metabolism of blood cells creates the preconditions for both genomic disorders and changes in genetic regulation.

The peculiarity of the blood system lies in the fact that pathological changes in it arise as a result of dysfunction not only of its individual components, but also of other organs and systems of the body as a whole. Any disease, pathological process, as well as a number of physiological changes can, to one degree or another, affect the quantitative and qualitative characteristics of the composition of circulating blood. This determines the enormous importance of the need to study blood (as the “blood mirror of the body”) and reveal the patterns of its changes in various diseases.

Purpose of the study: to consider and study the morphology of the blood system and its age-related features.

To achieve this goal, the following tasks were solved:

.Consider the components of the blood system and their morphology.

.Determine age-related characteristics of the blood system.

1. Morphology of the blood system

1.1 Peripheral blood and its elements

Peripheral blood is blood circulating through vessels outside the hematopoietic organs. In a healthy adult, blood accounts for an average of 7% of body weight

Depending on the vessels in which blood flows, its types are distinguished: arterial, venous, capillary. There are differences between these types of blood in biochemical and morphological parameters, but they are insignificant. For example, the concentration of hydrogen ions (medium pH) in arterial blood is 7.35 - 7.47; venous - 7.33 - 7.45. This value is of great physiological importance, as it determines the rate of many physiological and chemical processes in the body.

The absolute majority of circulating blood cells are erythrocytes - red, anucleate cells. Their number in men is 4.710 + - 0.017 x 10.12 / l, in women - 4.170 + - 0.017 x 10.12 / l. In a healthy person, 85% of red blood cells have a discoid shape with biconvex walls, and 15% have other shapes. The diameter of the erythrocyte is 7-8 microns, thickness is 1-2.4 microns. The cell membrane of an erythrocyte is 20 nm thick. Its outer surface consists of lipids, oligosaccharides, which determine the antigenic composition of the cell - blood group, sialic acid and protein, and the inner surface - of glycotic enzymes, sodium, potassium, ATP, glycoprotein and hemoglobin. The cavity of the erythrocyte is filled with granules (4.5 nm) containing hemoglobin.

The red blood cell is a highly specialized cell whose main task is to transport oxygen from the pulmonary alveoli to tissues and carbon dioxide (CO 2) - back from the tissues to the pulmonary alveoli. The biconcave shape of the cell allows for the largest surface area for gas exchange. The diameter of an erythrocyte is about 8 microns, however, the features of the cell skeleton and membrane structure allow it to undergo significant deformation and pass through capillaries with a lumen of 2-3 microns. This ability to deform is provided by the interaction between membrane proteins (segment 3 and glycophorin) and cytoplasm (spectrin, ankyrin and protein 4.1). Defects in these proteins lead to morphological and functional disorders of red blood cells. A mature erythrocyte does not have cytoplasmic organelles and a nucleus and therefore is not capable of synthesizing proteins and lipids, oxidative phosphorylation and maintaining reactions of the tricarboxylic acid cycle. It obtains most of its energy through the Embden-Meyerhof anaerobic pathway and stores it as ATP.

Approximately 98% of the mass of proteins in the cytoplasm of an erythrocyte is hemoglobin (Hb), the molecule of which binds and transports oxygen. The process of binding and releasing oxygen by hemoglobin molecules depends on the pressure of oxygen, carbon dioxide, pH and temperature of the environment.

The lifespan of red blood cells corresponds to 120+-12 days, which was determined using a radioactive label. Red blood cells are distinguished between young (neocytes), mature and old. Neocytes are the most resistant to influence, which is especially evident when they are frozen with various cryoprotectants and thawed. The gradual aging of a cell leads to disruption of metabolic processes and its death. About 200 billion red blood cells die in the human body every day. Their remains are absorbed by macrophages of the spleen and liver.

The next largest number of cells in the blood are platelets - blood platelets. Their number in the blood of a healthy person is 150,000 - 400,000/μl. Platelets, the smallest blood cells, are formed from the largest bone marrow cells - megakaryocytes. Platelets in circulating blood have a round or oval shape, with a diameter of 2.5 microns. There is no nucleus in the cell. The structure of blood platelets is divided into a single-layer membrane, a peripheral structureless zone (hyalomere) and a central granular zone (granulomere). Dense microtubules are detected in the hyalomere by electron microscopy. They play the role of the cell skeleton, as well as participation in the process of clot retraction. The granulomere contains mitochondria, ribosomes, alpha granules, dense bodies, and glycogen particles. Alpha granules contain acid phosphatase, B-glucuronidase, and cathepsin, which makes it possible to classify them as lysosomes that determine cell function. Dense bodies contain serotonin, which contracts blood vessels during release, ATP and ADP, which are involved in adhesion and the release reaction.

Normal platelets are distinguished: young (4.2+-0.13%), mature (88.2+-0.19%), old (4.1+-0.21%) and forms of irritation (2.5 +-0.1%) degenerative and vacuolated.

humoral (plasma) system, consisting of procoagulant proteins;

cellular system consisting of platelets.

The end result of activation of the humoral coagulation system is the formation of a fibrin clot, or red thrombus, while the platelet reaction, accompanied by cell adhesion and aggregation, results in the formation of a platelet plug, or white thrombus. Although these two coagulation systems are usually considered separately, it should be understood that in fact their functions are closely intertwined. Soluble clotting factors (eg fibrinogen and von Willebrand factor) have great importance for normal platelet function, and, conversely, platelets are important suppliers of procoagulant proteins and a necessary catalyst for a number of reactions in the soluble blood coagulation system.

In general, the hemostatic functions of platelets explain their ability to adhesion, aggregation, formation of a primary platelet clot at the site of damage to the wall of a blood vessel and the release of coagulation factors involved in fibrin loss and retraction of the resulting clot.

In addition to their main function, blood platelets carry a number of vasoactive substances - serotonin, histamine and catecholamines, and maintain the function of the vascular endothelium. Platelets, having phagocytic activity, are able to absorb fat droplets, viruses, bacteria, and immune complexes. Blood plates are involved in inflammatory processes and immunological reactions. They contain both specific antigens, characteristic only of platelets (HPA: 1-5), and antigens of the ABO, MN, P systems, the major histocompatibility complex HLA, but there are no antigens of the Rh, Daffy, Kell, Kidd systems. The most immunogenic antigens are the A and B loci and the least are the C locus of the HLA system.

The average lifespan of a platelet is 9.5+-0.6 days. Normally, 2/3 of a person’s blood platelets are in the circulating blood and 1/3 in the spleen and are a kind of reserve for rapid mobilization if necessary. There is a dynamic exchange between these parts.

The total number of platelets in the human body ranges from 1.0 to 1.5 trillion; they are renewed per day (1.1 - 1.73) x10.11. The process of the terminal stage of thrombocytopoiesis is not well understood. It is possible that in response to a certain signal, megakaryocytes are transformed into spider-like cells, from which many long filamentous processes (proplatelets) extend with uniform foci of constriction. Proplatelet cells enter the medullary sinusoids and are fragmented into platelets there, possibly due to the shear force of the blood flow. Although end-stage thrombocytopoiesis is limited to only the most mature megakaryocytes, it is a regulated process. After a sharp increase in the peripheral demand for platelets, an increase in the volume of these cells is immediately detected, which reflects changes in the mechanism of platelet formation.

White blood cells, or leukocytes, are the basis of the body's antimicrobial defense. This heterogeneous group of “defenses” includes the main effectors of immune and inflammatory responses.

The term "leukocyte" refers more to the appearance of the cell (leukos - white Greek) observed in a blood sample after centrifugation.

Neutrophils.

Neutrophil granulocytes are the most large group circulating leukocytes. The term "neutrophil" describes appearance cytoplasmic granules using Wright-Giemsa staining. Together with eosinophils and basophils, neutrophils belong to the class of granulocytes. Due to the presence of a characteristic multilobar (segmented) nucleus, the neutrophil is also called a polymorphonuclear leukocyte (PMNL). Granulocytes have sizes of 9-15 microns, exceeding those of erythrocytes. In the protoplasm of all granulocytes, granularity is detected: aerophilic and special. Aerophilic granules contain mainly acid phosphatase, while special granules contain alkaline phosphatase. The main function of granulocytes is phagocytosis.

The phagocytic activity of neutrophils is most pronounced in young people; as people get older, it decreases. In addition to phagocytosis, granulocytes exhibit secretory activity during inflammation, releasing a number of antibacterial agents: peroxidases, bactericidal lysosomal cationic proteins and other substances. These highly specialized cells migrate to sites of infection where they recognize, capture and destroy bacteria. This function is possible due to the ability of neutrophils to chemotaxis, adhesion, movement and phagocytosis. They have a metabolic apparatus for producing toxic substances and enzymes that destroy microorganisms.

Granulocytes live 1-6 days, on average 6-9 days, while their residence time in the bone marrow is 2-6 days. They circulate with the blood for 60-90 minutes. up to 24 hours, sometimes up to 2 days. A small part of granulocytes is destroyed in the blood, the majority enters the tissues and ends its physiological existence. Granulocytes are destroyed by macrophages of the lungs, spleen, and liver. Some of the granulocytes are excreted from the body with secretions and excreta, sputum, saliva, bile, urine, and feces.

Eosinophils.

Eosinophils have a bilobed nucleus and a cytoplasm filled with clearly visible granules that turn red after Wright-Giemsa staining. The basic (positively charged) proteins of these granules stain red due to their high affinity for eosin. Although eosinophils undergo the same stages of maturation as neutrophils, due to their small number, eosinophil precursors in the bone marrow are detected less frequently (with the exception of some pathological conditions: worms, allergies).

Basophils.

Basophils are the smallest group of circulating granulocytes, making up less than 1% of leukocytes. The large cytoplasmic granules of basophils contain sulfated or carboxylated acidic proteins, such as heparin, which appear blue when stained with Wright-Giemsa. Basophils mediate allergic reactions, especially those based on IgE-dependent mechanisms. They express IgE receptors and, when stimulated appropriately, release histamine in response to IgE and antigen.

Monocytes.

Monocytes circulate in the peripheral blood as large cells with blue/gray cytoplasm and a kidney-shaped or folded nucleus containing delicate reticulate chromatin. Monocytes are a derivative of COE-GM (common precursor for granulocytes and monocytes) and COE-M (precursor of monocytic lineage only). Monocytes spend only about 20 hours in the bloodstream and then enter peripheral tissues, where they transform into macrophages of the reticuloendothelial system (RES). These tissue macrophages, or histiocytes, are large cells with an eccentrically located nucleus and vacuolated cytoplasm containing numerous inclusions.

Monocytes and macrophages are long-lived cells whose functional characteristics are in many ways similar to those of granulocytes. They more effectively capture and absorb microbacteria, fungi and macromolecules; their role in the phagocytosis of pyogenic bacteria is less significant. In the spleen, macrophages are responsible for the disposal of sensitized and senescent red blood cells. Macrophages play an important role in processing and presenting antigens to lymphocytes during cellular and humoral immune responses. Their production of cytokines and interleukins, interferons and complement components contributes to coordination in the integrated immune response.

Normally, monocytes make up 1 to 10% of circulating leukocytes. When the number of monocytes exceeds 100/μl, we can talk about monocytosis, which is observed in patients with chronic infections (tuberculosis, chronic endocarditis) or inflammatory processes (autoimmune diseases, inflammatory diseases intestines).

Lymphocytes.

A significant population of leukocytes consists of lymphocytes. Based on their structure, they are conventionally divided into small (5-9 microns), medium (10 microns) and large (11-13 microns). The lymphocyte is currently considered the main cell of the immune system. These are small mononuclear cells that coordinate and execute the immune response by producing inflammatory cytokines and antigen-specific binding receptors.

Lymphocytes are divided into two main categories: B cells and T cells - and several smaller classes, such as natural killer cells. Subsets of lymphocytes differ in the site of their formation and the effector molecules they express, but share a common feature - the ability to mediate a highly specific antigenic response. Lymphocytes are able to move and penetrate other cellular elements. A small part of lymphocytes have phagocytic activity. The main function of a lymphocyte is to participate in immune reactions. For example, T-lymphocytes are active participants in the rejection reaction, the graft-versus-host reaction; B-lymphocytes produce antibodies that determine the humoral immune response.

Lymphocytes can retain immunological memory for a long time. Under the influence of a number of immune and chemical (mutogens) factors they are able to proliferate.

The generation of lymphocytes in an adult occurs mainly in the bone marrow and thymus gland.

The lifespan of lymphocytes is different: for short-lived ones (obviously, those that participate in immune reactions) - 3-4 days, for long-lived ones - 100-200 days and even 580 days. Their presence in the circulating blood does not exceed 40 minutes. The total number in the circulating blood of an adult is 7.5x10.9 lymphocytes, and in the body, taking into account the reserve of these cells in the bone marrow, spleen, lymph nodes, thymus, tonsils and Peyer's patches - 6.0x10.12.

Old lymphocytes die in the circulating blood and are eliminated by the reticulo-macrophage elements of the capillaries.

B lymphocytes .

B lymphocytes express unique antigen receptors - immunoglobulins - and are programmed to produce them in large quantities in response to antigenic stimulation. B cells are formed from stem cells in the bone marrow. The term B cell comes from the Latin name for the bursa Fabricius, an organ necessary for the maturation of B cells in birds. Humans do not have a similar organ; B cell maturation occurs primarily in the bone marrow.

The immune system contains a large population of individual clones of B lymphocytes. Each clone expresses a unique antigen receptor that is essentially identical to the immunoglobulin molecule it produces. These molecules are different from each other and bind only to a limited number of antigens.

Mature B lymphocytes with characteristic surface antigens CD19 and CD20 are located mainly in the germinal centers of the lymph node cortex and in the white pulp of the spleen. B cells make up less than 20% of circulating lymphocytes.

T lymphocytes.

Having formed from bone marrow stem cells, T cells necessarily undergo a developmental stage in the thymus (thymus gland), resulting in the generation of mature, functional T cells.

According to the unitary theory, all blood cells come from one pluripotent undifferentiated (stem) cell. It has no morphological differences from a small lymphocyte.

Speaking from the formed elements of blood, it should be noted that after maturation in the bone marrow, they do not immediately enter the vascular bed. For some time, blood cells remain in special depots in the bone marrow and spleen. This reserve of additional blood is one of the factors regulating the constant composition of the blood. Once in the circulating flow, each blood cell functions for a certain time, gradually ages and is eliminated from the vascular bed. To replace old and eliminated cells, young formed elements come from hematopoietic tissue into the circulating blood during the process of physiological regeneration. This process is the main mechanism for maintaining a constant blood composition and an essential factor in ensuring homeostasis in the body.

Most of the blood is plasma. It has a complex multicomponent composition. The basis of plasma is water (90%), in which various proteins (7-8%) are dissolved, other organic compounds - glucose, enzymes, vitamins, acids, lipids (1.1%) and minerals (0.9%).

Protein components of plasma, together with platelets, provide the hemostatic function of the blood, participate in plastic processes in the tissues of the body, determine humoral immunity, detoxification and transport functions of the blood. In plasma, the concentration of total protein (normally 70-80 g/l), albumin (40-45%) and globulins (55-60%) is determined by electrophoretic method. Albumin is formed in the liver and is a low molecular weight (mw 69,000) protein. One third of its total amount (200-300 g) in the body of an adult is in the circulating blood, and two thirds are outside the vascular bed. There is a continuous exchange of albumin between these pools. It performs several functions: it maintains colloid-osmotic pressure in the blood and tissues (it accounts for 80% of the value of this indicator), on which transcapillary fluid exchange, tissue turgor and the volume of fluid in the extravascular and vascular spaces depend. Easily combining with organic and inorganic substances, hormones, drugs, albumin delivers them through the bloodstream to the tissues and at the same time removes some metabolic products into the vascular bed to the liver, kidneys, lungs, and gastrointestinal tract, promoting detoxification of the body. It is one of the important components of the plasma buffer system, regulating the acid-base state of the blood. Participates in tissue nutrition as an easily digestible protein.

The next group of proteins consists of globulins, which have a high (105.00-900.000) molecular weight. They account for 15-18% of the value of maintaining colloid-osmotic blood pressure. Their main function is to provide humoral immunity.

When using the immunological method, plasma proteins are divided into 3 classes - A, M, G. Antibodies against the vast majority of infectious agents are contained in class G.

Among hemostatic plasma proteins, the most prominent place is given to factors VIII and IX of the blood coagulation system, which are currently obtained in pure form.

Plasma contains several humoral systems: complementary (complement components are involved in the binding of antigens to antibodies), coagulation and anti-inflammatory systems, oxidative and antioxidant systems, kallekrein, properdin, nonspecific protective factors, humoral immunity factors and others. Plasma contains various protein complexes (glycoproteins, metalloproteins, lipoproteins, etc.), hormones, and other biologically active substances, which makes it possible to obtain valuable therapeutic drugs from it.

The physiological role of a number of plasma ingredients has not yet been sufficiently studied and requires further research.

blood platelet immunity age

1.2 Organs of hematopoiesis and blood destruction

A common feature of the histological structure of the hematopoietic organs is the presence in their composition of parenchyma of reticular (in the case of the thymus - reticuloepithelial) connective tissue, which performs a number of special functions: 1) trophism of the hematopoietic tissue itself, 2) delimitation of groups of maturing formed elements belonging to different lines of differentiation, 3 ) are “chemical beacons” for reducing blood cells (lymphocytes, etc.).

The hematopoietic organs include the red bone marrow, lymph nodes, spleen, thymus, and the hematopoietic organs include the liver, bone marrow, and spleen.

Red bone marrow

structural features: honeycomb-like structure (due to the abundance of fat cells)

functions: hematopoietic (all types and germs of hematopoiesis), immune (the place of formation of the precursors of B- and T-lymphocytes, differentiation and maturation of T-lymphocytes occurs in the thymus). The destruction of cells (erythrocytes), recycling of iron, and synthesis of Hb also occur in it.

Spleen.

localization: in the left hypochondrium, along the blood vessels

structural features: the largest peripheral hematopoietic organ; covered with peritoneum and a capsule of connective tissue with a high content of smooth myocytes (give the organ the ability to contract); trabeculae extend from the capsule deep into the organ, anastomosing with each other; in the parenchyma, white and red pulp are distinguished: the first is represented by many lymphoid follicles (nodules), the second - by blood vessels, reticular tissue and the splenic cords lying in the nodes of the latter - special cellular associates, which include erythrocytes, platelets, leukocytes, macrophages, plasma cells and etc.; it is believed that it is in the splenic cords that the destruction of old blood cells occurs, primarily erythrocytes and blood platelets;

functions: hematopoietic (formation of B-lymphocytes), protective (phagocytosis, participation in immune reactions), storage (operational blood depot, accumulation of platelets), destruction of old and damaged red blood cells, leukocytes, platelets.

Thymus (thymus gland)

localization: behind the sternum

age dynamics: reaches its greatest development in childhood; after puberty undergoes gradual involution; by old age, it is almost completely replaced by adipose tissue (since a significant part of T-lymphocytes is represented by long-lived cells capable of selective proliferation when encountering an antigen, age-related atrophy of the thymus does not lead to a catastrophic decrease in immunity)

structural features: covered with a connective tissue capsule, septa extending from it divide the organ into lobules; in each lobule the cortex and medulla are distinguished; the parenchyma of the lobules is formed by the precursors of T-lymphocytes (migrated to the thymus from the red bone marrow), T-lymphocytes at various stages of differentiation and reticuloepithelial tissue; layered thymic corpuscles are located in the medulla, presumably performing an endocrine function

functions: a) hematopoietic (the place of formation of the first lymphocytes in the embryo), b) immune, c) endocrine (secretes a number of hormones and hormone-like substances that stimulate the reproduction and differentiation of T lymphocytes and regulate certain parts of the immune response).

Lymph node

localization: along the lymphatic vessels

structural features: the organ is bean-shaped, on the convex side several afferent lymphatic vessels approach the lymph node, on the opposite side there is a gate through which the efferent lymphatic vessel and veins exit and the artery and nerves enter; covered with a connective tissue capsule, from which trabeculae extend deep into the organ; in the parenchyma, the cortex and medulla are distinguished, the first is formed by spherical lymphoid follicles (nodules, which are dense accumulations of lymphocytes), the second by pulpal cords - branching and anastomosing cords consisting of many lymphocytes; tissue composition of the parenchyma: hematopoietic tissue (B-lymphocytes, plasma cells, macrophages, etc.) and reticular tissue; the spaces through which lymph moves within the node are called sinuses

functions: hematopoietic (formation of B-lymphocytes), protective (filtration of lymph, phagocytosis, participation in the immune response - in the lymph nodes B-lymphocytes are converted into plasma cells - antibody producers)

Amygdala.

localization: depending on the topography, the pharyngeal, laryngeal, tubal, lingual and palatine tonsils are distinguished

structural features: the tonsil belongs to the so-called lymphoepithelial organs and is an accumulation of lymphoid follicles (nodules) around a finger-like (or slit-like) ingrowth of the epithelium into the underlying connective tissue; has its own capsule

functions: hematopoietic (formation of lymphocytes), protective (phagocytosis, local immunity)

1.3 Neurohumoral regulation

Neurohumoral regulation is a form of regulation of physiological processes in the body, carried out by the central nervous system and biologically active substances of body fluids (blood, lymph and tissue fluid). Plays a leading role in maintaining homeostasis, i.e. the constancy of the internal environment of the body, and the adaptation of the body to changing conditions of existence.

Neurohumoral regulation arose in the process of animal evolution as a result of the combination of two forms of regulation of the body’s vital activity - the more ancient humoral (with its help, communication was carried out between individual cells or organs due to substances released from them in the process of metabolism) and nervous (which took control of activity of the humoral regulatory system). In the processes of N. r. in addition to direct transmitters of nervous excitation, i.e. mediators, tissue hormones, hypothalamic neurohormones, regulatory peptides and other biologically active substances take part. They are distributed throughout the body through the bloodstream, but only affect the resulting organs (target organs), interacting with the receptor (target cell). Under their influence, the adreno-, cholinergic, histamine- and serotonin-reactive structures of the body are excited. In particular, the neurosecretory cells of the hypothalamus are the site of transformation of nervous stimuli into humoral ones, and humoral ones into nervous ones. Under certain conditions, biologically active substances form a link in the reflex arc, i.e. transmit information to the central nervous system, where it is processed and then returned in the form of a stream of nerve impulses to the executive organs (effectors).

The presence of histohematic barriers determines the selective penetration of hormones, mediators and other biologically active substances from the blood only into strictly defined areas of the brain. However, if the permeability of the barrier is disrupted, biologically active substances can penetrate into those parts of the brain that are usually closed to these substances, which can lead to the development of unusual conditions, even pathological ones, affecting both the peripheral and central parts of the nervous system. Violations of the mechanisms of N. r. can also lead to a mismatch of certain parameters of the internal environment of the body and, as a consequence, to the development of various pathological conditions.

2. Age-related features of the blood system

At the end of the 19th century, the outstanding French physiologist Claude Bernard formulated the position of the constancy of the internal environment of the body (homeostasis) as a necessary condition for maintaining the vital functions of the body. This property was improved in the process of evolution, when mechanisms supporting it were formed, and warm-blooded animals introduced highest level development of this function.

During ontogenesis, in each age period, blood has its own characteristic features. They are determined by the level of development of the morphological and functional structures of the organs of the blood system, as well as neurohumoral mechanisms for regulating their activity.

2.1 General properties of blood in ontogenesis

The total amount of blood in relation to the body weight of a newborn is 15%, in children of one year - 11%, and in adults - 7-8%. At the same time, boys have slightly more blood than girls. However, at rest, only 40-45% of the blood circulates in the vascular bed, the rest is in the depot: the capillaries of the liver, spleen and subcutaneous tissue - and is included in the bloodstream when body temperature rises, muscle work, blood loss, etc.

The specific gravity of the blood of newborns is slightly higher than that of older children, and is respectively 1.06-1.08. The blood density established in the first months (1.052-1.063) remains until the end of life.

Blood viscosity in newborns is 2 times higher than in adults and is 10.0-14.8 arb. units By the end of the first month, this value decreases and usually reaches average figures - 4.6 conventional units. units (relative to water). Blood viscosity values ​​in elderly people do not exceed normal limits (4.5).

2.2 Biochemical properties of blood

In humans, the chemical composition of blood is characterized by significant constancy. The greatest deviations, if we take the content of substances in the blood of adults as the norm, can be noted during the neonatal period and in old age.

The total protein content in the blood serum of healthy newborns is 5.68+-0.04 g%. With age, this amount increases, growing especially rapidly in the first three years. At 3-4 years, these values ​​practically reach the level of adults (6.83+-0.19 g). Attention should be paid to the wider range of individual protein levels in children early age(from 4.3 to 8.3 g%), compared with adults, in whom these values ​​were 6.2-8.2 g%. The lower level of protein in the blood plasma in children in the first months of life is explained by the insufficient function of the body's protein-forming systems.

During ontogenesis, the ratio between albumins and various fractions of globulins in the blood plasma also changes. In the first months of life, the content of albumin in the blood is reduced (3.7 g); by 6 years this value increases to 4.1 g%, and by 3 years it was 4.5 g%, which is close to the norm for an adult. The amount of gamma globulins, high in the first days after birth due to maternal plasma, gradually decreases, and then by 3 years it reaches the adult norm (17.39 g). The content of alpha1-globulins in children under 1 year of age is increased; by 3 years of age their level in the blood is normalized. The determination of the concentration of alpha2-globulins proceeds somewhat differently. In the first six months their level is elevated, by the age of 7 it gradually decreases, and then reaches the level characteristic of adults. The content of beta globulins also reaches adult levels after 7 years.

Thus, the protein composition of the blood undergoes a number of changes during ontogenesis: from birth to adulthood, the protein content in the blood increases, and certain ratios in protein fractions are established. Functionality levels of organs synthesizing plasma proteins, primarily the liver, are relatively low at the time of birth, gradually increasing, which leads to normalization of blood composition.

Picture 1

The amount of cholesterol (Fig. 1) in the blood of newborns is relatively low and increases with age. It is noted that when carbohydrates predominate in food, the level of cholesterol in the blood increases, and when proteins predominate, it decreases. In old age and old age, cholesterol levels increase.

The level of lactic acid in an infant can be 30% higher than that in adults, which is associated with an increase in the level of glycolysis in children. With age, the content of lactic acid in a child's blood gradually decreases. Thus, the level of lactic acid in a child in the first 3 months of life is 18.7 mg%, by the end of 1 year - 13.8 mg%, and in adults - 10.2 mg%.

2.3 Formed elements of blood in ontogenesis

Erythropoiesis. The number of red blood cells in the fetus gradually increases, and there is a decrease in their diameter, volume and number of nucleated cells. In newborns, the intensity of erythropoiesis is approximately 5 times higher than in adults. The number of red blood cells in them on the 1st day is increased compared to adults and reaches 6-10 x1012 /l. On the 2-3rd day their quantity decreases as a result of their destruction (physiological jaundice) and during the 1st month their content decreases to 4.7x1012 / l. In this case, anisocytosis, poikilocytosis and polychromatophilia are detected, and sometimes nucleated red blood cells are also found. During the first half of the year, infants are characterized by a further decrease in the number of red blood cells, after which their number increases to 4.2x1012 / l. Starting from the age of 4, there is a decrease in myeloid tissue and during puberty, hematopoiesis remains in the red bone marrow of the spongy substance of the vertebral bodies, ribs, sternum, leg bones and femurs. With aging, there is a decrease in the total mass of red bone marrow and its proliferative activity. There is a tendency towards a decrease in the number of red blood cells and hemoglobin.

Hemoglobin. The function of oxygen carrier in the embryo up to 9-12 weeks is performed by embryonic (primitive) hemoglobin (HbP), which is replaced by fetal hemoglobin (HbF) by the 3rd month of intrauterine development. At the 4th month, adult hemoglobin (HbA) appears in the fetal blood and its amount does not exceed 10% until 8 months. Newborns still retain up to 70% HbF and already contain 30% HbA. The amount of Hb is increased (170 - 246 g/l), but, starting from the 1st day, its content gradually decreases. In elderly and senile people, the Hb content decreases slightly and fluctuates within the lower limit of the norm for mature age. ESR in newborns is lower than in adults and is 1-2 mm/h.

Leukocytes. In newborns, immediately after birth, the number of leukocytes is increased and reaches 15 x 1012/l (leukocytosis of newborns). After 6 hours, their number increases to 20 x1012/l, after 24 hours - 28 x1012/l, 48 hours - 19 x1012/l. The regeneration index is increased and a shift in the leukocyte formula to the left is noted. The highest increase in the number of leukocytes is observed on the 2nd day. Then their number decreases and the maximum drop in the curve occurs on the 5th day, and by the 7th day their number approaches the upper limit of the adult norm. In infants, there is a relatively low motor and phagocytic activity of leukocytes. The picture of white blood in children after the 1st year of life is characterized by a gradual decrease in the absolute number of leukocytes, an increase in the relative number of neutrophils with a corresponding decrease in the number of lymphocytes. In the leukocyte formula, 2 “crossovers” of changes in leukocytes are noted. The first - at the age of 3 - 7 days (decrease in the percentage of neutrophils and increase in the percentage of lymphocytes) and the second - at the age of 4-6 years (increase in the percentage of neutrophils and decrease in the percentage of lymphocytes). With old age, leukopenia (leukopenia of old age) and eosinopenia are noted. The functional reserve of leukopoiesis decreases under extreme conditions.

Platelets. The number of platelets in newborns in the first hours after birth ranges from 150 to 320 x 109 /l, which on average does not differ significantly from their content in the blood of adults. This is followed by a slight decrease in their quantity (up to 164-178x109 / l) by 7-9 days, after which by the end of the 2nd week their content increases and remains practically without significant changes at the level of adults. Children 1 day of life are characterized by a large number of round and young forms of platelets, the number of which decreases with age.

Hemostasis. There is no fibrinogen, prothrombin and accelerin in the blood of the fetus until 16 - 20 weeks, and therefore it does not clot. Fibrinogen appears at 4-5 months of intrauterine life, its concentration is 0.6 g/l. During this period, the activity of the fibrin-stabilizing factor is still low, but the activity of heparin is high (almost 2 times higher than in adults). The low level of factors of the coagulation and anticoagulation systems of the blood in the fetus is explained by the immaturity of the cellular structures of the liver that carry out their biosynthesis. In the blood of newborns, there is a low concentration of a number of factors (FII, FVII, FIX, FX, FXI, FXIII) of the blood coagulation system, anticoagulants and plasminogen, although the ratio of their concentrations is the same as in adults. In children in the first days of life, blood clotting time is reduced, especially on the 2nd day, after which it gradually increases and reaches the blood clotting rate in adults by the end of adolescence. During childhood, there is a gradual increase in the content of procoagulants and anticoagulants. In this case, heterochronic maturation of individual links (pro- and anticoagulants) in a given postnatal period is characteristic. By the age of 14-16 years, the content and activity of all factors involved in blood coagulation and fibrinolysis reach adult levels.

Blood groups. The formation of factors that determine group membership in ontogeny does not occur simultaneously. Agglutinogens A and B are formed by 2 - 3 months of the antenatal period, and agglutinins alpha and beta - at the time of or after birth, which determines the low ability of erythrocytes to agglutinate, which reaches its level in adults by 10 - 20 years.

Agglutinogens of the Rh system appear in the fetus at 2 - 3 months, while the activity of the Rh antigen in the prenatal period is higher than in adults.

2.4 Leukoformula

The number of leukocytes in a child in the first days of life is greater than in adults, and on average ranges from 10,000-20,000 per cubic meter. mm. Then the white blood cell count begins to fall. As with erythrocytes, there is a wide range of fluctuations in the number of leukocytes in the first days of postnatal life from 4600 to 28000. The following is characteristic of the picture of leukocytes in children of this period. An increase in the number of leukocytes during 3 hours of life (up to 19,600), which is apparently associated with the resorption of decay products of the child’s tissues, tissue hemorrhages possible during childbirth, after 6 hours - 20,000, after 24 - 28,000, after 48 - 19,000 By the 7th day, the number of leukocytes approaches the upper limit of adults and amounts to 8000-11000. In children 10-12 years old, the number of leukocytes in the peripheral blood ranges from 6-8 thousand, i.e. corresponds to the number of leukocytes in adults.

The leukocyte formula also has its own age-related characteristics. Let us remember that this means the ratio of different forms of leukocytes as a percentage.

Figure 2

The leukocyte formula of a child’s blood during the neonatal period is characterized by:

) a consistent increase in the number of lymphocytes from the moment of birth to the end of the neonatal period (at the same time, on the 5th day there is an intersection of the curves of the fall of neutrophils and the rise of lymphocytes);

) a significant number of young forms of neutrophils;

) a large number of young forms, myelocytes, blast forms;

) structural immaturity and fragility of leukocytes.

In children of the first year of life, with a fairly wide range of fluctuations in the total number of leukocytes, wide ranges of variations in the percentage of individual forms are also observed (Fig. 2).

Conclusion

The blood system is vital to the human body. It includes bone marrow, spleen, lymph nodes, liver, circulating and deposited blood. This is a very dynamic system that clearly responds to exogenous and endogenous influences on the human body and responds with unique reactions to changes occurring in it.

During ontogenesis, in each age period, blood has its own characteristic features. They are determined by the level of development of the morphological and functional structures of the organs of the blood system, as well as neurohumoral mechanisms for regulating their activity.

The blood system subtly responds to physical and chemical influences from the external and internal environments of the body, therefore blood tests provide the basis for important general biological conclusions, allowing one to correctly and most accurately diagnose and, on this basis, formulate a conclusion about the presence and type standard form pathology of the blood system, its possible causes, mechanisms of development and outcome.

Literature

1.Human anatomy. /Ed. Sapina M.R. In 2 volumes. - M.: Medicine, 1997.

.Atlas of blood cells and bone marrow (edited by G.I. Kozinets). - M.: "Triad-X", 1998, - 160 p.

2.Age-related features of the blood system / A.A. Markosyan, Kh.D. Lomazova. - Moscow, 2002 // Reader on developmental physiology: textbook: for higher education students educational institutions, studying in the specialties - “Preschool pedagogy and psychology”, “Pedagogy and methods of preschool education” / Comp. MM. Bezrukikh, V.D. Sonkin, D.A. Farber. - Moscow: Academy, 2002. - P. 81-102.

.Ermolaev Yu.A. Age physiology. Textbook for students of pedagogical universities. - M.: Higher School, 1985, 384 p.

5.Kurepina M.M. Human anatomy. - M.: Education, 1979.

.The beginnings of physiology: Textbook for universities / Edited by academician. HELL. Nozdracheva. - St. Petersburg: Lan Publishing House, 2001. - 1088 p.

.Pathological physiology / Ed. V.V. Novitsky, E.D. Goldberg - Tomsk, 2001 - pp. 136-141

8.Guide to hematology in 3 volumes, volume 1. / Ed. Vorobyova A.I. Ed. "Newdiamed". M., 2002, 280 s

.Guide to hematology in 3 volumes, volume 2. / Ed. Vorobyova A.I. Ed. "Newdiamed". M., 2003, 270 p.

.Shiffman Fred. J., Blood Pathophysiology, St. Petersburg, 2000

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