Blood, its meaning, composition and general properties. The physiological significance of blood

The value of blood for the human body

Blood is liquid complex composition circulating in the circulatory system. Comprises individual components- plasma ( clear liquid pale yellow) and blood cells suspended in it: erythrocytes (red blood cells), leukocytes (white blood cells), and platelets (platelets). The red color of blood is given by red blood cells due to the presence of the red pigment hemoglobin in them. The volume of blood in the body of an adult is on average about 5 liters, more than half of this volume is plasma.

Blood performs in the human body whole line vital functions, the main of which are:

Transport of gases, nutrients and metabolic products

Almost all processes associated with such vital functions as breathing and digestion take place with the direct participation of blood. Blood carries oxygen from the lungs to the tissues (red blood cells play the main role in this process) and carbon dioxide from the tissues to the lungs. Blood delivers to tissues nutrients, it also removes metabolic products from the tissues, which are then excreted in the urine.

Body protection

An important role in the fight against infection is played by leukocytes, which destroy foreign microorganisms, as well as dead or damaged tissue, thus preventing the infection from spreading throughout the body. Leukocytes and plasma also have great importance to maintain immunity. White blood cells form antibodies (special plasma proteins) that fight infection.

Maintaining body temperature

By transferring heat between different tissues of the body, blood provides a balanced absorption and release of heat, thereby maintaining normal temperature body, which healthy person is 36.6°C.

Story therapeutic use blood

Vital importance blood for the human body was recognized by people in ancient times. Accordingly, attempts to use the blood of animals and people for medicinal purposes have been known since ancient times, however, due to a lack of scientific knowledge many similar experiences best case were useless, at worst - ended tragically. However, attempts medicinal use blood can be noted throughout history. Hippocrates believed that mental illness can be treated by giving the sick to drink the blood of healthy people. The ancient authors Pliny and Celsus in their writings report that patients with epilepsy as remedy drank the blood of dying gladiators.

Since ancient times, blood has been credited with a rejuvenating effect. There is evidence that Pope Innocent VIII, who lived in the 15th century, while dying, drank blood taken from three boys of 10 years old (which, however, did not save him). The legends of various peoples attribute to the legendary villains of the past the desire to drink the blood or even bathe in the blood of their victims.

From ancient times to the 19th century, bloodletting was widely used as a remedy, which can bring some relief in acute heart failure, pulmonary edema, hypertensive crises, some poisonings. In the Middle Ages and modern times, this method of treatment gained such popularity that it was written about the French surgeon F. Bruset that he shed more blood than Napoleon for all his wars. Nowadays, indications for bloodletting are strictly limited, although such a method of treatment, for example, using medicinal leeches sometimes still used today.

What are the functions of blood in the body of an animal?

What color is blood in animals and why?

Transport (nutritional), excretory, thermoregulatory, humoral, protective

The color of the blood of animals depends on the metals that are part of the blood cells (erythrocytes), or substances dissolved in the plasma. All vertebrates, as well as earthworm, leeches, houseflies and some mollusks in a complex combination with blood hemoglobin is iron oxide. That is why their blood is red. The blood of many marine worms contains a similar substance, chlorocruorin, instead of hemoglobin. Ferrous iron was found in its composition, and therefore the color of the blood of these worms is green. And scorpions, spiders, crayfish, octopuses and cuttlefish blood is blue. Instead of hemoglobin, it contains hemocyanin, with copper as the metal. Copper also gives their blood a bluish color.

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1. What components does it consist of internal environment? How are they related?

The internal environment of the body consists of blood, tissue fluid and lymph. Blood moves through a system of closed vessels and does not directly contact tissue cells. Tissue fluid is formed from the liquid part of the blood. It got its name because it is located among the tissues of the body. Nutrients from the blood enter the tissue fluid and into the cells. The decay products move in the opposite direction. Lymph. Excess tissue fluid enters the veins and lymphatic vessels. In the lymphatic capillaries, it changes its composition and becomes lymph. Lymph moves slowly through the lymphatic vessels and eventually enters the blood again. Previously, lymph passes through special formations - The lymph nodes where it is filtered and disinfected, enriched with lymphatic cells.

2. What is the composition of blood and what is its significance for the body?

Blood is a red, opaque liquid composed of plasma and formed elements. Distinguish between red blood cells (erythrocytes), white blood cells (leukocytes) and platelets(platelets). In the human body, blood connects every organ, every cell of the body with each other. The blood carries the nutrients obtained from food to the digestive organs. It delivers oxygen from the lungs to the cells, and carbon dioxide, harmful, waste substances are carried to those organs that neutralize them or remove them from the body.

3. Name shaped elements blood and their functions.

Platelets are platelets. They are involved in blood clotting. Erythrocytes are red blood cells. The color of red blood cells, erythrocytes, depends on the hemoglobin they contain. Hemoglobin is able to easily combine with oxygen and easily give it away. Red blood cells carry oxygen from the lungs to all organs. Leukocytes are white blood cells. Leukocytes are extremely diverse and fight germs in many ways.

4. Who discovered the phenomenon of phagocytosis? How is it carried out?

The ability of certain leukocyte cells to capture microbes and destroy them was discovered by I.I. Mechnikov - the great Russian scientist, laureate Nobel Prize. Leukocyte cells of this type I.I. Mechnikov called phagocytes, i.e., eaters, and the process of destroying microbes by phagocytes - phagocytosis

5. What are the functions of lymphocytes?

The lymphocyte has the appearance of a ball, on its surface there are numerous villi, similar to tentacles. With their help, the lymphocyte examines the surface of other cells, looking for foreign compounds - antigens. most often they are found on the surface of phagocytes that have destroyed foreign bodies. If only “own” molecules are found on the surface of cells, the lymphocyte moves on, and if strangers, the tentacles, like claws of cancer, close. Then the lymphocyte sends chemical signals through the blood to other lymphocytes, and they begin to produce according to the found pattern. chemical antidotes- antibodies consisting of gamma globulin protein. This protein is released into the blood and settles on various cells such as erythrocytes. Antibodies often go beyond blood vessels and are located on the surface of skin cells, respiratory tract, intestines. They are a kind of trap for foreign bodies such as microbes and viruses. Antibodies either stick them together, or destroy them, or dissolve them, in short, disable them. At the same time, the constancy of the internal environment is restored.

6. How does blood coagulation occur?

When blood flows from the wound to the surface of the skin, the platelets stick together and break down, and the enzymes they contain are released into the blood plasma. In the presence of calcium and vitamin K salts, the plasma protein fibrinogen forms fibrin strands. Red blood cells and other blood cells get stuck in them, and a blood clot forms. It doesn't let blood flow out.

7. How are human erythrocytes different from frog erythrocytes?

1) Human erythrocytes do not have a nucleus, frog erythrocytes are nuclear.

2) Human erythrocytes are shaped like a biconcave disk, while frog erythrocytes are oval.

3) Human erythrocytes are 7-8 µm in diameter, frog erythrocytes are 15-20 µm long and about 10 µm wide and thick.

BLOOD

The internal environment of the body and its relative constancy. Blood, lymph and tissue fluid form the internal environment of the body. The internal environment provides an inextricable link between the body and external environment, it is distinguished by the constancy of composition and properties, and this is necessary for normal life cells.

The constancy of the composition is achieved by the activity of many organs and systems that supply the body with the substances necessary for life and remove decay products. Nutrients and water enter the body through the digestive organs, oxygen through the respiratory organs, and decay products and water are excreted through the excretory organs. Tissue fluid is formed from plasma - the liquid part of the blood - and is found in the spaces between cells. Nutrients and oxygen from the capillaries, due to the difference in concentrations, first enter the tissue fluid, and from it are absorbed by the cells. Water, carbon dioxide and other metabolic products formed in the cells, also according to the laws of diffusion and osmosis, are released from the cells, first into the tissue fluid, and then enter the capillaries. Blood changes from arterial to venous. In the intercellular spaces, blindly ending lymphatic capillaries originate, they receive tissue fluid, which then becomes lymph in the lymphatic vessels. Lymph is a slightly yellowish liquid consisting of lymphoplasm and formed elements. In terms of chemical composition, it is close to blood plasma, but contains half as much protein. Lymph is 95% water and contains proteins. mineral salts, fats, glucose and shaped elements - lymphocytes and monocytes.

Lymph and blood belong to the connective tissue. The total amount of blood in the body of an adult is normally 6-8 percent of body weight. Blood consists of formed elements: erythrocytes, leukocytes and platelets (platelets) - and a liquid intercellular substance - plasma. The blood cells account for 40-45 percent of the total blood volume, and the plasma volume is 55-60 percent.

Admission constituent parts tissue fluid from the blood and its reverse outflow into the lymph and into the blood depends on the state of numerous biological membranes providing selective permeability. The relative constancy of the internal environment is one of important factors providing homeostasis of the body.

Physiological significance blood lies in the fact that, being in continuous motion, it performs certain functions:

1. Trophic (nutritional) function, transfers nutrients to cells that enter it from digestive tract, as well as from the bodies in which they are deposited.

2. Respiratory function, carries oxygen from the lungs to tissue cells, and carbon dioxide from the cells to the lungs.

3. excretory function, delivers the decay products of substances to the kidneys and other excretory organs.

4. transport function, transfers various substances from some organs and systems to other tissues, organs and systems of the body.

5. Regulatory function, transfers hormones and other biologically active substances, with the help of which hormonal regulation of the activity of organs and systems of the body occurs.

6. Thermoregulatory function, supports constant temperature body, retain heat or increase heat transfer in cases of hypothermia or overheating of the body.

7. Homeostatic function, maintains the constancy of the internal environment, keeps the osmotic pressure of blood and tissue fluid constant, as well as the content of proteins, glucose, calcium, potassium, sodium, phosphorus, chlorine, hydrogen ions in them.

8. The protective function is provided by the ability of some forms of leukocytes to phagocytosis, as well as the presence of antibodies in the blood, with which immunity is associated.

As a function of blood, the ability to coagulate can be distinguished, which protects the body from bleeding and blood loss.

Composition of the blood

Blood consists of a liquid intercellular substance - plasma and cellular elements suspended in it - erythrocytes, leukocytes and platelets (platelets). Blood plasma contains 90-92 percent water, 7-8 percent proteins, 0.12 percent glucose, 0.8- 2.0 percent fat and 1.0 percent minerals.

Plasma proteins are divided into three main groups according to their functions and properties - albumins (4.5 percent), globulins (1.7-3.5 percent) and fibrinogen (0.4 percent). Globulins are involved in protecting the body from bacteria and their toxins. Albumins maintain colloid osmotic pressure and regulate plasma water content. fibrinogen plays important role during the process of blood clotting. Blood plasma devoid of fibrinogen is called serum.

Mineral substances include cations of sodium, potassium, calcium, magnesium, iron and anions of chlorine, sulfur, iodine, phosphate. Most of all in the plasma of sodium and chlorine ions. This is used in clinical practice and at big losses blood or fluid. An isotonic solution containing 0.85-0.90 percent sodium chloride is injected into the veins.

Erythrocytes are non-nucleated red blood cells that have the shape of biconcave discs. This form increases the cell surface by 1.5 times and is the most beneficial for gas exchange. The cytoplasm of erythrocytes contains hemoglobin, a protein organic compound, consisting of the protein globin and the blood pigment heme, which contains iron. The diameter of a human erythrocyte is 7.5 microns, and the surface is 125 sq. microns. 1 mm3 of blood contains an average of 4.5-5.0 million erythrocytes. In total, there are an average of 25 trillion red blood cells in the human body with a total surface area of ​​3700 square meters. m, which is 1500 times larger than the surface of the human body. The main function of red blood cells is to transport oxygen from the respiratory organs to the tissues and remove carbon dioxide from the tissues. In the lungs, hemoglobin attaches oxygen and is called oxyhemoglobin (HbO2). This is a fragile connection and in the capillaries of tissues, oxyhemoglobin, which has given up oxygen, is called reduced hemoglobin. In addition to oxygen, hemoglobin can combine with carbon monoxide (CO). This compound is called carboxyhemoglobin and is 300 times stronger than hemoglobin and oxygen. When carboxyhemoglobin is formed, oxygen is not added, which is life-threatening.

At education carbon monoxide in the room, you must immediately open the windows and let the victim breathe fresh air or take him out to Fresh air. In the most severe cases, artificial respiration is done.

Erythrocytes are formed from nuclear cells in the red bone marrow of the spongy bone. Life expectancy is about 130 days, and then they are destroyed in the spleen and liver, and bile pigment is formed from hemoglobin.

Leukocytes are white blood cells that contain a nucleus and are capable of amoeboid movement. The total number of leukocytes in human circulating blood is 6-8 thousand per 1 mm3. They are formed in the red bone marrow, spleen and lymph nodes, their life expectancy is 2-4 days and are destroyed in the spleen. The number of leukocytes fluctuates under the influence of various factors e.g. after a meal or physical work there are more of them. A person has several types of leukocytes, which differ from each other in size, shape of the nucleus (in some leukocytes, the nucleus consists of several parts), the presence or absence of granularity in the cytoplasm.

The main function of leukocytes is to protect the body from bacteria, foreign proteins, foreign bodies. Leukocytes move by releasing pseudopods. Stretching into thin threads, leukocytes pass through the walls of the capillaries, exit the bloodstream and penetrate into all parts of the body. Leukocytes are characterized by chemotaxis, they rush to the foci of inflammation, places of tissue decay and accumulations of bacteria. Approaching microbes, leukocytes envelop them with their pseudopodia, cover and absorb into the protoplasm, where, with the participation of enzymes, they disintegrate. At the same time, leukocytes themselves often die, as a result of which pus forms in the places of their accumulation.

Platelets are the smallest colorless, non-nuclear formed elements of the blood, they are platelets. 1 mm3 contains 200-300 thousand platelets. They are formed in the red bone marrow, have a size of 2-4 microns. Life expectancy 3-4 days. Accumulating in the spleen, they form a depot, from where platelets, if necessary, enter the blood. When blood vessels are damaged and when blood comes into contact with air, platelets are easily destroyed and secrete a special substance thromboplastin, which promotes blood clotting and clot formation.

Test

On the subject " Age anatomy, Physiology and Hygiene"

1 Blood: meaning, composition, age features and blood functions.
1.1 Cardiovascular system and its functions…………………..
1.2 Blood and its functions………………………………………………...
1.3 Composition of blood………………………………………………………
1.4 Age features of blood…………………………………
1.5 Blood diseases……………………………………………………
2 Sleep, its physiological significance for preschool children……….
2.1 Sleep, the meaning of sleep………………………………………………...
2.2 Transient states and foci of excitation during sleep…..
2.3 Hypnosis as partial sleep………………………………………
2.4 hygiene organization sleep………………………………...
3. The essence and principles of hardening of the body………………………
3.1 Basic principles of hardening………………………………
3.2 Types of hardening………………………………………………..
3.3 Principles and types of hardening in my kindergarten…………
Bibliographic list………………………………………………

1 Blood: meaning, composition, age characteristics and functions of blood

1.1 Cardiovascular system and its functions

The human organ system is organs similar in structure, development and functions, united together into a single, coordinated working structure. In the human body, there are: integumentary, musculoskeletal, digestive, circulatory, lymphatic, respiratory, excretory, reproductive, endocrine and nervous systems.

Let's take a closer look at the cardiovascular system.

The cardiovascular system (abbreviated as CCC) is an organ system that provides blood and lymph circulation throughout the human and animal body.

Part of cardio-vascular system includes: blood vessels, lymphatic vessels, blood and main body circulation - heart

The main significance of the cardiovascular system is the supply of blood to organs and tissues.

The main function of the cardiovascular system is to ensure the flow of physiological fluids - blood and lymph. Other functions of the cardiovascular system follow from the main function:

1. Providing cells with nutrients and oxygen;

2. Removal of waste products from cells;

3. Ensuring the transfer of hormones and, accordingly, participation in hormonal regulation bodily functions;

4. Participation in the processes of thermoregulation (due to the expansion or narrowing of the blood vessels of the skin) and providing uniform distribution body temperature;

5. Ensuring the redistribution of blood between working and non-working organs;

6. Production and transfer of immunity cells into the bloodstream and immune bodies(this function is performed lymphatic system part of the cardiovascular system).

1.2 Blood and its functions

Blood is a liquid tissue circulating in the circulatory system of vertebrates and humans.

The blood volume of an adult male is approximately 75 ml per kilogram of body weight; at adult woman this figure is approximately 66 ml. Accordingly, the total blood volume in an adult male is on average about 5 liters; more than half of the volume is plasma, and the rest is mainly erythrocytes. The volume of blood in a child (per 1 kg of weight) is relatively larger than in an adult, but the paths of its movement through the vessels are shorter and the blood circulation rate is higher. The vessels are relatively wide, and the blood flow through them from the heart is not hindered. Thus, the volume of blood in a child depends on his age and weight., A newly born child has 140 ml of blood per 1 kg of body weight, then this figure gradually decreases and by the year is 100 ml/kg. At the same time than less baby, the higher specific gravity his blood.

Blood circulating continuously closed system blood vessels, performs various functions in the body:

Transport (nutritional) blood provides cells with nutrients (glucose, amino acids, fats) substances, water, vitamins, minerals. transport of nutrients from the digestive tract to tissues, places of reserve reserves from them (trophic function).

respiratory function - the transfer of oxygen from the lungs to the tissues and carbon dioxide from the tissues to the lungs, the storage of oxygen;

Excretory - removes unnecessary metabolic products from tissues; transport of metabolic end products from tissues to excretory organs (excretory function);

Thermoregulatory - regulates body temperature - redistribution of heat between organs, regulation of heat transfer through the skin;

Humoral - connects various bodies and systems, transferring the signal substances that are formed in them; transport of hormones and other biologically active substances from the places of formation - from the glands internal secretion to the organs.

Protective - blood cells are actively involved in the fight against foreign microorganisms. carried out due to the phagocytic activity of leukocytes ( cellular immunity), the production of antibodies by lymphocytes that neutralize genetically alien substances ( humoral immunity); The protective function of blood is aimed at preventing rises in the blood concentration of exogenous toxic substances and poisons. Leukocytes remove foreign compounds of biological origin from the body by the formation of specific antibodies in the reactions of humoral and cellular immunity.

mechanical function - giving tension to the organs due to the rush of blood to them; ensuring ultrafiltration in the capillaries of the capsules of the nephron of the kidneys, etc.;

homeostatic function - maintaining the constancy of the internal environment of the body, suitable for cells in terms of ionic composition, concentration of hydrogen ions, etc. The homeostatic role of blood is to stabilize important constants of the body (concentration of hydrogen ions, pH, osmotic pressure, ionic composition of tissues).

blood clotting to prevent blood loss;

Blood provides water-salt metabolism of cells.

Plasma proteins can be used by the body as a source of amino acids.

Partially, the transport function in the body is also performed by lymph and intercellular fluid.

Physiological significance of blood. Blood as the internal environment of the body.

Ministry of Health of the Republic of Belarus

EE "Gomel State Medical University"

Department of Normal Physiology

Discussed at the meeting of the department

Minutes No. __________200__

LECTURE №2.

in normal physiology for 2nd year students

Subject: Body fluids. The blood system. Properties.

Time 90 minutes

Educational and educational goals:

1. Give an idea of ​​the meaning of blood, functions.

LITERATURE

Fundamentals of human physiology. Edited by B.I. Tkachenko. - St. Petersburg, 1994. - T.1. - S. 6-15.

Human physiology. Edited by R. Schmidt and G. Thevs. - M., Mir. - 1996. - T.1. - p.9.

Human physiology. Ed. V.M. Pokrovsky, G.F. Korotko. M., Medicine. - 2000.-T..1-C 277 - 285.

MATERIAL SUPPORT

1. Multimedia presentation 28 slides.

CALCULATION OF STUDY TIME

Total 90 min

The effective activity of the cells of the body is ensured by the constancy of its internal environment. The internal environment of the body that has direct contact with the cell is the intercellular (interstitial) fluid. In turn, the constancy of the intercellular fluid is determined by the composition of blood, lymph, spinal, intra-articular, pleural, peritoneal and other fluids. The constantly flowing exchange between the fluid spaces of the body ensures the continuous supply to the cells of substances necessary for the exchange and removal of metabolic products.

permanence chemical composition And physical and chemical properties The internal environment of the body is called homeostasis. Homeostasis is the dynamic constancy of the internal environment, which is characterized by a set of relatively constant quantitative indicators (parameters) called physiological (biological) constants, among which the blood constants are the most important .. 0ni provide optimal conditions the vital activity of the cells of the body and reflect its normal state.

The most important component of the internal environment of the body is blood - liquid connective tissue organism. G. F. Lang (1939) put forward the concept of "blood system". The blood system includes: blood that regulates the neurohumoral apparatus, as well as organs in which the formation and destruction of blood cells (bone marrow, lymph nodes, thymus, spleen, liver).

2. Main functions of blood:

1. Respiratory - delivery of oxygen to cells and removal of carbon dioxide.

2. Trophic (nutritional) - blood provides cells with nutrients (glucose, amino acids, fats) substances, water, vitamins, minerals.

3. Excretory - removal from the cells of the end products of metabolism.

4. Thermoregulatory - blood ensures the stabilization of temperature conditions for the cell by transporting thermal energy generated in actively functioning cells.

5. The protective function of blood is aimed at preventing rises in the concentration of exogenous toxic substances and poisons in the blood, which are critical for the cell, by means of their nonspecific adsorption on the surface of blood cells and the formation of complexes with plasma proteins, followed by their removal from the body by excretory organs. Leukocytes remove genetically alien compounds of biological origin from the body by phagocytosis, cytolysis, hydrolysis or the formation of specific antibodies in the reactions of humoral and cellular immunity.

6. The homeostatic role of blood is to stabilize important body constants (concentration of hydrogen ions-pH, osmotic pressure, ionic composition of tissues).

7. Blood provides water-salt metabolism of cells.

8. Circulating blood provides communication between organs -important condition humoral regulation functions in the body. Blood carries hormones and other biologically active substances from the sites of formation to target cells.

9. Transport is a consequence of the functioning of the myocardium as a pump, the contraction energy of which ensures the movement of blood through vascular system organism and its contact with all anatomical and functional systems of the organism.

10. Plasma proteins can be used by the body as a source of amino acids.

Blood has the ability to clot, which prevents life-threatening blood loss from damage to tissues and blood vessels.

Total blood in the body of an adult is 6 - 8% of body weight, or approximately 4.5 - 6 liters. Massive blood loss of about 1/3 of its volume (about 1.5 liters) is accompanied by a fall blood pressure and subsequent death of the organism.

What do you know about the meaning of blood?

Tatiana*******

The value of blood for the body

Blood is a complex fluid that circulates in the circulatory system. It consists of individual components - plasma (a clear pale yellow liquid) and blood cells suspended in it: erythrocytes (red blood cells), leukocytes (white blood cells) and platelets (platelets). The red color of blood is given by red blood cells due to the presence of the red pigment hemoglobin in them. The volume of blood in the body of an adult is on average about 5 liters, more than half of this volume is plasma.

Blood performs a number of vital functions in the human body, the main of which are:

Transport of gases, nutrients and metabolic products

Almost all processes associated with such vital functions as breathing and digestion take place with the direct participation of blood. Blood carries oxygen from the lungs to the tissues (red blood cells play the main role in this process) and carbon dioxide from the tissues to the lungs. Blood delivers nutrients to the tissues, it also removes metabolic products from the tissues, which are then excreted in the urine.

Body protection

An important role in the fight against infection is played by white blood cells, which destroy foreign microorganisms, as well as dead or damaged tissues, thereby preventing the infection from spreading throughout the body. Leukocytes and plasma are also of great importance for maintaining immunity. White blood cells form antibodies (special plasma proteins) that fight infection.

Maintaining body temperature

By transferring heat between various tissues of the body, the blood provides a balanced absorption and release of heat, thereby maintaining a normal body temperature, which in a healthy person is 36.6 ° C.

Blood is the key body fluid. Its fundamental function is to provide the body with oxygen and other important substances, elements involved in the process of life. Plasma, the constituent of blood and cellular components, are separated by meaning and type. Cell groups are divided into following groups: red blood cells (erythrocytes), white cells (leukocytes) and platelets.

In an adult, the volume of blood is calculated taking into account the weight of his body, approximately 80 ml per 1 kg (for men), 65 ml per 1 kg (for women). Most of total number blood accounts for plasma, red cells occupy a significant proportion of the remaining amount.

How blood works

The simplest organisms living in the sea exist without blood. The role of blood in them is taken over by sea water, which through the tissues saturates the body with all the necessary components. Decomposition and exchange products also come out with water.

The human body is more complex, because it cannot function by analogy with the simplest. That is why nature endowed man with blood and a system for distributing it throughout the body.

Blood is responsible not only for the function of supplying nutrients to systems, organs, tissues, the release of residual waste products, but also controls the temperature balance of the body, supplies hormones, and protects the body from the spread of infections.

Nevertheless, the delivery of nutrients is a key function that the blood performs. Exactly circulatory system has a connection with all digestive and respiratory processes without which life is impossible.

Main functions

Blood in the human body performs the following vital tasks.

1. Blood performs a transport function, which consists in supplying the body with all the necessary elements and purifying it from other substances. The transport function is also divided into several others: respiratory, nutritional, excretory, humoral.
2. The blood is also responsible for maintaining a stable body temperature, that is, it plays the role of a thermoregulator. This feature has special meaning- some organs need to be cooled, and some require warming.
3. The blood contains leukocytes and antibodies that protective function.
4. The role of the blood is also to stabilize many constant values ​​in the body: osmotic pressure, pH, acidity, and so on.
5. Another function of blood in providing water-salt metabolism that is happening with her tissues.

red blood cells

Red blood cells make up slightly more than half of the body's total blood volume. The value of erythrocytes is determined by the content of hemoglobin in these cells, due to which oxygen is provided to all systems, organs and tissues. It is worth noting that the carbon dioxide formed in the cells is carried back to the lungs by erythrocytes for further exit from the body.

The role of hemoglobin is to facilitate the attachment and removal of oxygen molecules and carbon dioxide. Oxyhemoglobin has a bright red color and is responsible for the addition of oxygen. When the tissues of the human body absorb oxygen molecules, and hemoglobin forms a compound with carbon dioxide, the blood becomes darker in color. A significant decrease in the number of red blood cells, their modification and lack of hemoglobin in them are considered the main symptoms of anemia.

Leukocytes

White blood cells are larger than red blood cells. In addition, leukocytes can move between cells by protrusion and retraction of their body. White cells differ in the shape of the nucleus, while the cytoplasm of individual white cells is characterized by granularity - granulocytes, others do not differ in granularity - agranulocytes. The composition of granulocytes includes basophils, neutrophils and eosinophils, agranulocytes include monocytes and lymphocytes.

The most numerous type of leukocytes are neutrophils, they perform the protective function of the body. When foreign substances, including microbes, enter the body, neutrophils are sent to the same source of damage to neutralize it. This value of leukocytes is extremely important for human health.

The process of absorption and digestion of a foreign substance is called phagocytosis. The pus that forms at the site of inflammation is a lot of dead leukocytes.

Eosinophils are so named because of their ability to acquire a pinkish tint when eosin, a coloring matter, is added to the blood. Their content is approximately 1-4% of the total number of leukocytes. The main function of eosinophils is to protect the body from bacteria and determine reactions to allergens.

When infections develop in the body, antibodies are formed in the plasma that neutralize the action of the antigen. In the process, histamine is produced, which causes local allergic reaction. Its action is reduced by eosinophils, and after the infection is suppressed, they also eliminate the symptoms of inflammation.

Plasma

Plasma consists of 90-92% water, the rest is represented by salt compounds and proteins (8-10%). There are other nitrogenous substances in the plasma. Mostly these are polypeptides and amino acids that come from food and help the cells in the body produce proteins on their own.

In addition, plasma contains nucleic acids and protein degradation products that must be removed from the body. Included in the plasma and nitrogen-free matter - lipids, neutral fats and glucose. About 0.9% of all components in plasma are minerals. Even in the composition of the plasma there are all kinds of enzymes, antigens, hormones, antibodies and other things that can be important for the human body.

hematopoiesis

Hematopoiesis is the formation of cellular elements, which is carried out in the blood. Leukocytes are formed by a process called leukopoiesis, erythrocytes - erythropoiesis, platelets - thrombopoiesis. The growth of blood cells occurs in the bone marrow, which is located in the flat and tubular bones. Lymphocytes are formed, in addition to the bone marrow, also in the intestinal lymph tissue, tonsils, spleen and lymph nodes.

Circulating blood always maintains a relatively stable volume, the function it performs is so important, despite the fact that something is constantly changing inside the body. For example, fluid is constantly absorbed from the intestines. And if water enters the blood in a large volume, then it partially immediately leaves with the help of the kidneys, the other part enters the tissues, from where it eventually again penetrates into the bloodstream and completely exits through the kidneys.

If insufficient fluid enters the body, then the blood receives water from the tissues. The kidneys in this case do not function at full capacity, they collect less urine, and water is excreted from the body to a small extent. If the total volume of blood decreases by at least a third in a short period of time, for example, bleeding occurs or as a result of an injury, then this is already life-threatening.

Everyone will surely answer the question of what human blood is, however, most respondents will voice their answer in general phrases, since they do not have sufficient knowledge about the internal environment. Answers, as a rule, come down to hackneyed, banal expressions, and, meanwhile, the subject that reveals the meaning of blood for a person is fascinating and extensive. For many, learning rheological properties blood fluid is of the greatest interest of all disciplines related to medicine. Therefore, it makes sense to dwell on this issue in more detail and reveal it. main point, in which true value blood for the human body.

Man at all times positioned blood with something magical, gave it magical properties gave power over people. Liquid mobile connective tissue of the internal environment of the body was used for witchcraft, with its help they sent curses, healed, told fortune - in a word, blood for ancient people was not just a liquid. She was idolized, drank as a sign of unity and harmony. Partly for the ancients, it was such because of the lack of knowledge. For many millennia, its composition has been a secret with seven seals.

For a long time, doctors of the Middle Ages could not understand the causes of death of their patients when they treated them with blood transfusions. For some, transfusion turned out to be life-saving, for others it was a source of death. Therefore, this medical procedure contacted high risks. Only at the dawn of the 20th century did it become known why the blood of one person may not suit another.

Humanity owes the discovery of blood groups to the Austrian physician Karl Landsteiner. In 1900, he systematized its composition and designated each group as - "A", "B", and "C". Two years later, adherents of the Western European doctor A Sturli and A Decastello formulated in practice the fourth group "AB". These, without exaggeration, grandiose events served as an impetus for new, even more avalanche-like discoveries in the study of the properties of blood.

Thus, the first steps were taken towards understanding the "AB0" system, research was carried out in the field of blood clotting, its conservation and storage. Nowadays, the composition of human blood actually has no secrets, but every self-respecting doctor must know about it in detail. Today, for many people, in addition to its properties, various theories regarding the qualities of blood fluid are of interest. So, according to one of the latter, at first humanity had only one blood type - the first.

Question about the fourth group

Its owners are primitive hunters. They ate meat, fish, roots, berries. Over time, man learned to cultivate the soil, sow crops, harvest. So the owners of the second blood group appeared - farmers. Settlement gave rise to a new formation - nomads. They did not settle down in shelters and, in fact, were on the road all the time. The third blood group flowed in their veins. The formation of the fourth group is shrouded in darkness. According to two main theories, it appeared several millennia ago, however, what served as the impetus is still not clear. It is important to recall the most popular of them.

1. The composition of the blood of the fourth group was formed as a result of the mixing of races (migration of peoples, mixed marriages, etc.).
2. It appeared as a result of the defeat of people with viral or infectious diseases.

In any case, the fourth blood group is considered the youngest of all discovered. Today, virtually everything is known about the internal connective fluid environment of the human body. All conjectures and magical properties of the blood fluid are discarded in the tablets of history, the mechanisms, substances of blood, its composition have long been formulated and determined. However, in Japan, for example, there is still a rule according to which a candidate for a vacant position can be refused just because he does not match her blood type.

Fortunately, our employers are free from atypical prejudices. But still. What is its significance for a person, for an organism? According to many doctors, the composition of the blood fluid is universal. And really, there is nothing superfluous in it. And most importantly, it serves as a litmus test for determining the development of any pathological processes- especially complex and dangerous. A typical analysis like open book can tell the doctor about the state of human health, one has only to look at the form filled out by the laboratory assistant, which reflects the composition of the blood.

Why are platelets needed?

Its main purpose is to provide everything necessary for the cellular structure of the body and protect vital processes. Liquid connective tissue continuously delivers nutrients to all organs of the body, including oxygen, necessary element for human life. Back the blood takes the products of metabolism:

• slags;
• toxins;
• carbon dioxide.

way chemical reactions they break up into simple substances and are brought out with the help of the ZhTK, genitourinary system, sweat glands and lungs. The constant improvement of knowledge about blood helps doctors to penetrate deeper into the secrets of complex and dangerous diseases and therefore more effective treatment. If you look at the internal liquid medium under a microscope, you can see a lot of interesting things. Plasma, as blood is also called, is "filled with life." It circulates in an endless stream cellular elements: platelets, leukocytes, erythrocytes. At first glance, the thought comes to mind that this movement is chaotic, but if you know enough about blood, you come to the conclusion that this process is ordered and has its own structure.

The composition of the blood does not have extra elements. For example, platelets (platelets) provide strength to the walls of blood vessels. In comparison with other cells contained in the blood, they are the smallest, but the role assigned to them cannot but delight. At the slightest scratch, they "will lay down bones" to prevent profuse bleeding, that is, they immediately form a thrombus plug. It is these brave squirrels that we all see when the blood begins to clot before our eyes.

No less interesting is the work of hemostasis in the body - the balance that maintains the functionality of platelets. He doesn't let them curl up in bloodstream and at the same time activates the processes at the slightest injury.

Another function of platelets is to ensure the working condition of the internal surfaces of blood vessels and, as necessary, treat and nourish them. That is, their importance for the body is difficult to overestimate. A healthy person has 200-400 x10 9 /l. Least of all in newborns 100-400 x10 9 / l.

Oxygen Suppliers

As already mentioned, the composition of blood is universal and erythrocytes once again prove a fair statement. These disc-shaped cells, concave on both sides, play a key role in the life of each of us. They supply cells with oxygen and take in carbon dioxide. That is, without them, a person simply could not live. The most erythrocytes in the blood. There are five million red cells per cubic milliliter. It is easy to guess what value of erythrocytes will turn out if you calculate their number, taking as a basis the entire volume human blood, and its in healthy body about five liters. Having a spongy structure, the pores of red blood cells are clogged with hemoglobin. It is this form that provides excellent gas exchange in the body.

Rushing through the lungs, they capture fresh air and carry it to every cell. back - by venous blood RBCs deliver carbon dioxide to the lungs. In all these processes, hemoglobin is directly involved - it carries oxygen and releases the spent compound "CO 2". They are considered incorrigible workaholics in the body, which explains short term red cell life. On average, each erythrocyte exists for 3-4 months, and then, due to wear and tear, it ends up in the "cemetery", in the spleen. There it is destroyed and excreted with the excretory organs. This process does not stand still. Bone marrow immediately compensates for their deficiency, however, for a number of reasons, their number may decrease. Then the doctor will state the disease, anemia.

Leukocytes are fearless defenders

It is no less interesting to find out what effect leukocytes have on human life. Each person's blood composition contains a different amount of these white cells. It all depends on gender and age.

• In an adult male, the norm is 4.2 to 9 × 10 9 U / l.
• In a woman, 3.98 to 10.4 × 10 9 U / l.
• In a newborn, from 7 to 32 × 10 9 U / l.

closer to old age the value of the norm of leukocytes gradually decreases. It can be said without exaggeration that the biological life each of us depends on these little white cells. Leukocytes are the defenders of the body. They clearly track the alien invasion and do not spare own life, immediately rush at the enemy. The exciting process of the battle with pathogen can be described like this. The leukocyte detects the microbe by a specific substance and immediately goes to it. Then it forms a process, captures the “aggressor” with it, draws it into itself and digests it. This function inherent in the white cell is called phagocytosis. However, leukocytes also die in the fight against foreign organisms. If we examine the pus under a microscope, we can make sure that the main contents are dead bodies leukocytes.

Thanks to special properties, amoeboid movements, leukocytes can penetrate the walls of blood vessels and monitor the situation in the intercellular spaces. If the number of leukocytes is exceeded, this means leukocytosis. If they are less than normal - leukopenia. Now it is easy to draw conclusions to what extent human blood is a universal liquid and what is its significance.