The internal environment of the human body consists of a set of fluids circulating through it and ensuring its normal functioning. Its presence is characteristic of higher biological forms, including humans. In the article you will learn how the internal environment is formed, what types of tissue the internal environment is, and also why we need it.

What refers to the internal environment of the body?

The internal environment of the body includes three types of fluids, which are considered its components and serve to carry out life processes:

Of great importance for life is the constant mutual exchange of substances, which of the above forms the internal environment of the body. All these intercellular connective tissues of the internal environment have a common basis, but perform different functions.

The internal environment of a person does not include liquids that are waste products and are of no benefit to the body.

Let us consider in more detail the functions of the internal environment and its components.

When talking about the transport network, you can hear the expression “transport artery”. People compare railways and roads to blood vessels. This is a very accurate comparison, because the main purpose of blood is to transport beneficial elements throughout the body that enter the body from the external environment. Blood, which is a component of the internal environment of the body, also performs other tasks:

• regulation;
• breath;
• protection.

We will consider them a little later when describing its composition.

This substance moves along blood vessels without direct contact with organs. But part of the fluid that makes up the blood penetrates beyond the blood vessels and spreads throughout human body. It is located around each of its cells, forming a kind of shell, and is called tissue fluid.

Through tissue fluid, which is a component of the internal environment of the body, particles of oxygen and other useful components enter all organs and parts of the body. This happens at the cellular level. Each cell receives the necessary substances and oxygen from the tissue fluid, giving it carbon dioxide and waste products.

Its excess part changes its composition and is converted into lymph, which also belongs to the internal environment of the body, and enters the circulatory system. Lymph moves through vessels and capillaries, making up the lymphatic system. Large vessels form lymph nodes.

The lymph nodes

In addition to its transport function, lymph provides protection to the human body from pathogenic microbes and bacteria.

Blood and lymph, which are part of the internal environment of the human body, are an analogue of vehicles. They circulate inside our body and supply every cell with all the necessary nutritional components.

Homeostasis is necessary for the normal functioning of the body. This term denotes the constancy of the internal environment of the body, its structure and properties. Maintaining homeostasis occurs through interchange between the human body and the environment. When homeostasis is disrupted, there is a malfunction in the functioning of individual organs and the human body as a whole.

Composition of human blood and its properties

Blood has a complex structure and performs a whole range of different functions. Its basis is plasma. 90% of this liquid is water. The rest consists of proteins, carbohydrates, minerals, fats and other beneficial elements. Nutrients enter the plasma from digestive system. It carries them throughout the body, nourishing its cells.

Blood composition

Plasma contains a special protein called fibrinogen. It is capable of forming fibrin, which performs a protective function during bleeding. This substance is insoluble and has a thread-like structure. It forms a protective crust on the wound, preventing infection and stopping bleeding.

Fibrinogen

Doctors often use serum in their work. It is practically no different in composition from plasma. It lacks fibrinogen and some other proteins, which prevents it from coagulating.

Depending on the presence or absence of certain proteins and antibodies, it is divided into four groups. This classification is used to determine transfusion compatibility. People with the first blood group flowing in their veins are considered universal donors, since it is suitable for transfusion to any other groups.

The Rh factor is simply a type of protein. When Rh is positive, this protein is present, but when Rh is negative, it is absent. Transfusions can only be given to people with the same Rh factor.

Blood contains about 55% plasma. It also includes special cells called formed elements.

Table of blood elements

Name of elements	Cell components	Place of origin	Lifespan	Where they die off	Quantity per 1 cubic meter mm of blood	Purpose
Red blood cells	Red cells concave on both sides without a nucleus, which contain hemoglobin, which gives this color	Bone marrow	3 to 4 months	In the spleen (hemoglobin is neutralized in the liver)	About 5 million	Transporting oxygen from the lungs to the tissues, carbon dioxide and harmful substances back, participating in the respiratory process
Leukocytes	White blood cells with nuclei	In the spleen, red marrow, lymph nodes	3-5 days	In the liver, spleen and inflamed areas	4-9 thousand	Protection against microorganisms, production of antibodies, increased immunity
Platelets	Blood cell fragments	In red bone marrow	5-7 days	In the spleen	About 400 thousand	Participation in the process of blood clotting

Blood, lymph and tissue fluid supply the cells of our body with everything they need, allowing us to preserve health and ensure longevity.

Internal environment of the body- a set of body fluids located inside it, usually in certain reservoirs (vessels) and in natural conditions never in contact with the external environment, thereby providing the body with homeostasis. The term was proposed by the French physiologist Claude Bernard.

The internal environment of the body includes blood, lymph, tissue and cerebrospinal fluid.

The reservoir for the first two are vessels, blood and lymphatic, respectively, for cerebrospinal fluid - the ventricles of the brain and the spinal canal.

Tissue fluid does not have its own reservoir and is located between cells in body tissues.

Blood - liquid mobile connective tissue of the internal environment of the body, which consists of a liquid medium - plasma and cells suspended in it - shaped elements: leukocyte cells, postcellular structures (erythrocytes) and platelets (blood platelets).

The ratio of formed elements and plasma is 40:60, this ratio is called hematocrit.

Plasma is 93% water, the rest is proteins (albumin, globulins, fibrinogen), lipids, carbohydrates, and minerals.

Erythrocyte- a nuclear-free blood element containing hemoglobin. It has the shape of a biconcave disk. They are formed in the red bone marrow and destroyed in the liver and spleen. They live 120 days. Functions of red blood cells: respiratory, transport, nutritional (amino acids are deposited on their surface), protective (binding toxins, participating in blood clotting), buffering (maintaining pH with the help of hemoglobin).

Leukocytes. In adults, the blood contains 6.8x10 9 /l leukocytes. An increase in their number is called leukocytosis, and a decrease is called leukopenia.

Leukocytes are divided into 2 groups: granulocytes (granular) and agranulocytes (non-granular). The granulocyte group includes neutrophils, eosinophils and basophils, and the agranulocyte group includes lymphocytes and monocytes.

Neutrophils make up 50-65% of all leukocytes. They got their name from the ability of their grain to be painted with neutral colors. Depending on the shape of the nucleus, neutrophils are divided into young, band and segmented. Oxyphilic granules contain enzymes: alkaline phosphatase, peroxidase, phagocytin.

The main function of neutrophils is to protect the body from microbes and their toxins that have penetrated it (phagocytosis), maintain tissue homeostasis, destroy cancer cells, and secretory.

Monocytes the largest blood cells, make up 6-8% of all leukocytes, are capable of amoeboid movement, and exhibit pronounced phagocytic and bactericidal activity. Monocytes from the blood penetrate into tissues and there transform into macrophages. Monocytes belong to the mononuclear phagocyte system.

Lymphocytes make up 20-35% of white blood cells. They differ from other leukocytes in that they live not just a few days, but 20 or more years (some throughout a person’s life). All lymphocytes are divided into groups: T-lymphocytes (thymus-dependent), B-lymphocytes (thymus-independent). T lymphocytes differentiate from stem cells in the thymus. Based on their function, they are divided into killer T-cells, helper T-cells, suppressor T-cells, and memory T-cells. Provide cellular and humoral immunity.

Platelets– an anucleated blood plate involved in blood clotting and necessary to maintain integrity vascular wall. Formed in red bone marrow and in giant cells - megakaryocytes, they live up to 10 days. Functions: Active participation in the formation of a blood clot, Protective due to the gluing of microbes (agglutination), stimulate the regeneration of damaged tissues.

Lymph - a component of the internal environment of the human body, a type connective tissue, which is a transparent liquid.

Lymph consists of plasma and formed elements (95% lymphocytes, 5% granulocytes, 1% monocytes). Functions: transport, redistribution of fluid in the body, participation in the regulation of antibody production, transmission of immune information.

The following main functions of lymph can be noted:

· return of proteins, water, salts, toxins and metabolites from tissues to the blood;

· normal lymph circulation ensures the formation of the most concentrated urine;

· lymph carries many substances that are absorbed in the digestive organs, including fats;

· individual enzymes (for example, lipase or histaminase) can only enter the blood through the lymphatic system (metabolic function);

· lymph takes red blood cells from tissues, which accumulate there after injuries, as well as toxins and bacteria ( protective function);

· it provides communication between organs and tissues, as well as the lymphoid system and blood;

Tissue fluid is formed from the liquid part of the blood - plasma, penetrating through the walls of blood vessels into the intercellular space. Metabolism occurs between tissue fluid and blood. Part of the tissue fluid enters lymphatic vessels, lymph is formed.

The human body contains about 11 liters of tissue fluid, which provides cells with nutrients and removes their waste.

Function:

Tissue fluid washes tissue cells. This allows substances to be delivered to cells and waste products removed.

Cerebrospinal fluid , cerebrospinal fluid, liquor - fluid constantly circulating in the ventricles of the brain, liquor-conducting tracts, subarachnoid (subarachnoid) space of the brain and spinal cord.

Functions:

Protects the brain and spinal cord from mechanical influences, ensures the maintenance of constant intracranial pressure and water-electrolyte homeostasis. Supports trophic and metabolic processes between the blood and the brain, the release of products of its metabolism

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Internal environment of the human body

B) Superior and inferior vena cava D) Pulmonary arteries

7. Blood enters the aorta from:

A) Left ventricle of the heart B) Left atrium

B) Right ventricle of the heart D) Right atrium

8. Open leaflet heart valves occur at the moment:

A) Ventricular contractions B) Atrial contractions

B) Relaxation of the heart D) Transfer of blood from the left ventricle to the aorta

9. The maximum blood pressure is considered to be:

B) Right ventricle D) Aorta

10. The ability of the heart to self-regulate is evidenced by:

A) Heart rate measured immediately after exercise

B) Pulse measured before exercise

B) The rate at which heart rate returns to normal after exercise

D) Comparison of the physical characteristics of two people

It surrounds all cells of the body, through which metabolic reactions occur in organs and tissues. Blood (with the exception of hematopoietic organs) does not come into direct contact with cells. From blood plasma penetrating through the walls of capillaries, tissue fluid is formed that surrounds all cells. There is a constant exchange of substances between cells and tissue fluid. Part of the tissue fluid enters the thin, blindly closed capillaries of the lymphatic system and from that moment turns into lymph.

Since the internal environment of the body maintains constancy of physical and chemical properties, which persist even with very strong external influences on the body, then all the cells of the body exist in relatively constant conditions. The constancy of the internal environment of the body is called homeostasis. The composition and properties of blood and tissue fluid are maintained at a constant level in the body; bodies; parameters of cardiovascular activity and respiration and more. Homeostasis is maintained by the most complex coordinated work of the nervous and endocrine systems.

Functions and composition of blood: plasma and formed elements

In humans, the circulatory system is closed, and blood circulates through the blood vessels. Blood performs the following functions:

1) respiratory - transfers oxygen from the lungs to all organs and tissues and removes carbon dioxide from the tissues to the lungs;

2) nutritional - transfers nutrients absorbed in the intestines to all organs and tissues. In this way, the tissues are supplied with water, amino acids, glucose, fat breakdown products, mineral salts, vitamins;

3) excretory - delivers the end products of metabolism (urea, lactic acid salts, creatinine, etc.) from tissues to places of removal (kidneys, sweat glands) or destruction (liver);

4) thermoregulatory - transfers heat with blood plasma water from the place of its formation (skeletal muscles, liver) to heat-consuming organs (brain, skin, etc.). In the heat, the blood vessels in the skin dilate to release excess heat, and the skin turns red. In cold weather, skin vessels contract so that less blood enters the skin and it does not give off heat. At the same time, the skin turns blue;

5) regulatory - blood can retain or release water to tissues, thereby regulating the water content in them. Blood also regulates acid-base balance in tissues. In addition, it transports hormones and other physiologically active substances from the sites of their formation to the organs that they regulate (target organs);

6) protective - substances contained in the blood protect the body from blood loss due to the destruction of blood vessels, forming a blood clot. By this they also prevent the penetration of pathogenic microorganisms (bacteria, viruses, protozoa, fungi) into the blood. White blood cells protect the body from toxins and pathogens through phagocytosis and the production of antibodies.

In an adult, blood mass is approximately 6-8% of body weight and equals 5.0-5.5 liters. Some of the blood circulates through the vessels, and about 40% of it is in the so-called depots: vessels of the skin, spleen and liver. If necessary, for example during high physical exertion or blood loss, blood from the depot is included in the circulation and begins to actively perform its functions. Blood consists of 55-60% plasma and 40-45% formed elements.

Plasma is the liquid medium of blood, containing 90-92% water and 8-10% various substances. Plasma proteins (about 7%) perform a number of functions. Albumin - retains water in the plasma; globulins are the basis of antibodies; fibrinogen - necessary for blood clotting; various amino acids are transported by blood plasma from the intestines to all tissues; a number of proteins perform enzymatic functions, etc. Inorganic salts (about 1%) contained in plasma include NaCl, salts of potassium, calcium, phosphorus, magnesium, etc. A strictly defined concentration of sodium chloride (0.9%) is necessary to create stable osmotic pressure. If you place red blood cells - erythrocytes - in an environment with a lower NaCl content, they will begin to absorb water until they burst. In this case, a very beautiful and bright “varnish blood” is formed, which is not capable of performing the functions of normal blood. This is why water should not be introduced into the blood during blood loss. If red blood cells are placed in a solution containing more than 0.9% NaCl, it will be sucked out of the red blood cells and they will shrink. In these cases, the so-called physiological solution is used, which in terms of the concentration of salts, especially NaCl, strictly corresponds to blood plasma. Glucose is contained in blood plasma at a concentration of 0.1%. It is an essential nutrient for all body tissues, but especially the brain. If the glucose content in plasma decreases by approximately half (to 0.04%), then the brain is deprived of its source of energy, the person loses consciousness and can quickly die. Fat in blood plasma is about 0.8%. These are mainly nutrients carried by the blood to places of consumption.

The formed elements of blood include red blood cells, white blood cells and platelets.

Erythrocytes are red blood cells, which are anucleate cells that have the shape of a biconcave disk with a diameter of 7 microns and a thickness of 2 microns. This shape provides the red blood cells with the largest surface area in the smallest volume and allows them to pass through the smallest blood capillaries, quickly giving oxygen to tissues. Young human red blood cells have a nucleus, but as they mature, they lose it. Mature red blood cells of most animals have nuclei. One cubic millimeter of blood contains about 5.5 million red blood cells. The main role of red blood cells is respiratory: they deliver oxygen from the lungs to all tissues and remove a significant amount of carbon dioxide from the tissues. Oxygen and CO 2 in red blood cells are bound by the respiratory pigment - hemoglobin. Each red blood cell contains about 270 million hemoglobin molecules. Hemoglobin is a combination of protein - globin - and four non-protein parts - hemes. Each heme contains a molecule of ferrous iron and can add or donate an oxygen molecule. When oxygen joins hemoglobin in the capillaries of the lungs, an unstable compound is formed - oxyhemoglobin. Having reached the capillaries of the tissues, red blood cells containing oxyhemoglobin give oxygen to the tissues, and the so-called reduced hemoglobin is formed, which is now able to attach CO 2.

The resulting also unstable compound HbCO 2 gets into the lungs with the bloodstream, disintegrates, and the resulting CO 2 is removed through Airways. It should also be taken into account that a significant part of CO 2 is removed from tissues not by hemoglobin of erythrocytes, but in the form of carbonic acid anion (HCO 3 -), formed when CO 2 is dissolved in blood plasma. From this anion, CO 2 is formed in the lungs, which is exhaled out. Unfortunately, hemoglobin is capable of forming a strong connection with carbon monoxide(CO), called carboxyhemoglobin. The presence of only 0.03% CO in the inhaled air leads to the rapid binding of hemoglobin molecules, and red blood cells lose their ability to carry oxygen. In this case, rapid death from suffocation occurs.

Red blood cells are able to circulate through the bloodstream, performing their functions, for about 130 days. Then they are destroyed in the liver and spleen, and the non-protein part of hemoglobin - heme - is repeatedly used in the future in the formation of new red blood cells. New red blood cells are formed in the red bone marrow of the cancellous bone.

Leukocytes are blood cells that have nuclei. The size of leukocytes ranges from 8 to 12 microns. There are 6-8 thousand of them in one cubic millimeter of blood, but this number can fluctuate greatly, increasing, for example, in infectious diseases. This increased level of white blood cells in the blood is called leukocytosis. Some leukocytes are capable of independent amoeboid movements. Leukocytes ensure that the blood performs its protective functions.

There are 5 types of leukocytes: neutrophils, eosinophils, basophils, lymphocytes and monocytes. Most of all there are neutrophils in the blood - up to 70% of all leukocytes. Neutrophils and monocytes, actively moving, recognize foreign proteins and protein molecules, capture them and destroy them. This process was discovered by I.I. Mechnikov and he called it phagocytosis. Neutrophils are not only capable of phagocytosis, but also secrete substances that have a bactericidal effect, promoting tissue regeneration, removing damaged and dead cells from them. Monocytes are called macrophages and their diameter reaches 50 microns. They are involved in the process of inflammation and the formation of the immune response and not only destroy pathogenic bacteria and protozoa, but are also capable of destroying cancer cells, old and damaged cells in our body.

Lymphocytes play a critical role in the formation and maintenance of the immune response. They are able to recognize foreign bodies (antigens) on their surface and produce specific protein molecules (antibodies) that bind these foreign agents. They are also able to remember the structure of antigens, so that when these agents are reintroduced into the body, an immune response occurs very quickly, more antibodies are formed and the disease may not develop. The first to respond to antigens entering the blood are the so-called B lymphocytes, which immediately begin to produce specific antibodies. Some B lymphocytes turn into memory B cells, which exist in the blood for a very long time and are capable of reproduction. They remember the structure of the antigen and store this information for years. Another type of lymphocyte, T lymphocytes, regulates the functioning of all other cells responsible for immunity. Among them there are also immune memory cells. White blood cells are produced in the red bone marrow and lymph nodes and destroyed in the spleen.

Platelets are very small, non-nuclear cells. Their number reaches 200-300 thousand in one cubic millimeter of blood. They are formed in the red bone marrow, circulate in the bloodstream for 5-11 days, and then are destroyed in the liver and spleen. When a vessel is damaged, platelets release substances necessary for blood clotting, promoting the formation of a blood clot and stopping bleeding.

Blood groups

The problem of blood transfusion arose a long time ago. Even the ancient Greeks tried to save bleeding wounded soldiers by giving them warm animal blood to drink. But there could not be much benefit from this. At the beginning of the 19th century, the first attempts were made to transfuse blood directly from one person to another, but a very large number of complications were observed: after blood transfusion, red blood cells stuck together and were destroyed, which led to the death of the person. At the beginning of the 20th century, K. Landsteiner and J. Jansky created the doctrine of blood groups, which makes it possible to accurately and safely replace blood loss in one person (recipient) with the blood of another (donor).

It turned out that the membranes of red blood cells contain special substances with antigenic properties - agglutinogens. Specific antibodies dissolved in the plasma that belong to the globulin fraction - agglutinins - can react with them. During the antigen-antibody reaction, bridges are formed between several red blood cells and they stick together.

The most common system for dividing blood into 4 groups. If agglutinin α meets agglutinogen A after transfusion, red blood cells will stick together. The same thing happens when B and β meet. Currently, it has been shown that only the blood of his group can be transfused into a donor, although more recently it was believed that with small volumes of transfusion, the donor’s plasma agglutinins become highly diluted and lose their ability to glue the recipient’s red blood cells together. People with blood group I (0) can receive any blood transfusion, since their red blood cells do not stick together. Therefore, such people are called universal donors. People with blood group IV (AB) can be transfused with small amounts of any blood - these are universal recipients. However, it is better not to do this.

More than 40% of Europeans have blood group II (A), 40% - I (0), 10% - III (B) and 6% - IV (AB). But 90% of American Indians have I (0) blood type.

Blood clotting

Blood clotting is the most important protective reaction that protects the body from blood loss. Bleeding occurs most often due to mechanical destruction of blood vessels. For an adult man, a blood loss of approximately 1.5-2.0 liters is considered conventionally fatal, but women can tolerate a loss of even 2.5 liters of blood. In order to avoid blood loss, the blood at the site of vessel damage must quickly clot, forming a blood clot. A thrombus is formed by the polymerization of an insoluble plasma protein, fibrin, which, in turn, is formed from a soluble plasma protein, fibrinogen. The process of blood clotting is very complex, includes many stages, and is catalyzed by many enzymes. It is controlled by both nervous and humoral pathways. In a simplified way, the process of blood clotting can be depicted as follows.

There are known diseases in which the body lacks one or another factor necessary for blood clotting. An example of such a disease is hemophilia. Clotting is also slowed when the diet lacks vitamin K, which is necessary for the liver to synthesize certain protein clotting factors. Since the formation of blood clots in the lumens of intact vessels, leading to strokes and heart attacks, is deadly, the body has a special anticoagulant system that protects the body from vascular thrombosis.

Lymph

Excess tissue fluid enters blindly closed lymphatic capillaries and turns into lymph. In its composition, lymph is similar to blood plasma, but it contains much less proteins. The functions of lymph, like blood, are aimed at maintaining homeostasis. With the help of lymph, proteins are returned from the intercellular fluid to the blood. Lymph contains many lymphocytes and macrophages, and plays a large role in immune responses. In addition, the products of fat digestion in the villi of the small intestine are absorbed into the lymph.

The walls of the lymphatic vessels are very thin, they have folds that form valves, thanks to which the lymph moves through the vessel in only one direction. At the confluence of several lymphatic vessels there are lymph nodes that perform a protective function: they retain and destroy pathogenic bacteria, etc. The largest lymph nodes are located in the neck, groin, and axillary areas.

Immunity

Immunity is the body's ability to protect itself from infectious agents (bacteria, viruses, etc.) and foreign substances (toxins, etc.). If a foreign agent has penetrated the protective barriers of the skin or mucous membranes and entered the blood or lymph, it must be destroyed by binding to antibodies and (or) absorption by phagocytes (macrophages, neutrophils).

Immunity can be divided into several types: 1. Natural - congenital and acquired 2. Artificial - active and passive.

Natural innate immunity is transmitted to the body with genetic material from ancestors. Natural acquired immunity occurs when the body itself has developed antibodies to some antigen, for example, having had measles, smallpox, etc., and has retained the memory of the structure of this antigen. Artificial active immunity occurs when a person is injected with weakened bacteria or other pathogens (vaccine) and this leads to the production of antibodies. Artificial passive immunity occurs when a person is injected with serum - ready-made antibodies from a recovered animal or another person. This immunity is the most fragile and lasts only a few weeks.

Blood, tissue fluid, lymph and their functions. Immunity

Blood, lymph and tissue fluid form the internal environment of the body, which surrounds all its cells. The chemical composition and physicochemical properties of the internal environment are relatively constant, therefore the cells of the body exist in relatively stable conditions and are little exposed to environmental factors. Ensuring the constancy of the internal environment is achieved by the continuous and coordinated work of many organs (heart, digestive, respiratory, excretory systems), which supply the body with substances necessary for life and remove decay products from it. Regulatory function to maintain the constancy of the parameters of the internal environment of the body - homeostasis-for- carried out by the nervous and endocrine systems.

There is a close relationship between the three components of the body’s internal environment. So, colorless and translucent tissue fluid is formed from the liquid part of the blood - plasma, penetrating through the walls of the capillaries into the intercellular space, and from waste products coming from the cells (Fig. 4.13). In an adult, its volume reaches 20 liters per day. Blood supplies the tissue fluid with the dissolved nutrients, oxygen, hormones necessary for the cells and absorbs the waste products of the cells - carbon dioxide, urea, etc.

A smaller part of the tissue fluid, without having time to return to the bloodstream, enters the blindly closed capillaries of the lymphatic vessels, forming lymph. In appearance it is a translucent yellowish liquid. The composition of lymph is close to the composition of blood plasma. However, it contains 3-4 times less protein than plasma, but more than tissue fluid. Lymph contains a small number of leukocytes. Small lymphatic vessels merge to form larger ones. They have semilunar valves that ensure lymph flow in one direction - to the thoracic and right lymphatic ducts, which flow into

into the superior vena cava. In the numerous lymph nodes through which lymph flows, it is neutralized due to the activity of leukocytes and enters the blood purified. The movement of lymph is slow, about 0.2-0.3 mm per minute. It occurs mainly due to contractions of skeletal muscles, the suction action of the chest during inhalation and, to a lesser extent, due to contractions of the muscles of the own walls of the lymphatic vessels. About 2 liters of lymph return to the blood per day. In pathological phenomena that disrupt the outflow of lymph, tissue swelling is observed.

Blood is the third component of the internal environment of the body. This is a bright red liquid that continuously circulates in a closed system of human blood vessels and makes up about 6-8% of the total body weight. The liquid part of the blood - plasma - makes up about 55%, the rest is formed elements - blood cells.

IN plasma about 90-91% water, 7-8% proteins, 0.5% lipids, 0.12% monosaccharides and 0.9% mineral salts. It is plasma that transports various substances and blood cells.

Plasma proteins fibrinogen And prothrombin take part in blood clotting, globulins play an important role in the body's immune reactions, albumins impart viscosity to the blood and bind calcium present in the blood.

Among blood cells most red blood cells- red blood cells. These are small biconcave disks without a nucleus. Their diameter is approximately equal to the diameter of the narrowest capillaries. Red blood cells contain hemoglobin, which easily binds to oxygen in areas where its concentration is high (lungs), and just as easily releases it in areas with low oxygen concentration (tissues).

Leukocytes- white nuclear blood cells are slightly larger in size than red blood cells, but contain much less of them in the blood. They play an important role in protecting the body from disease. Due to their ability of amoeboid movement, they can pass through small pores in the walls of capillaries in places where pathogenic bacteria are present and absorb them by phagocytosis. Other

types of white blood cells are capable of producing protective proteins - antibodies- in response to a foreign protein entering the body.

Platelets (blood platelets)- the smallest of blood cells. Platelets contain substances that play an important role in blood clotting.

One of the most important protective functions of blood - protective - is carried out with the participation of three mechanisms:

A) blood clotting, thanks to which blood loss is prevented due to injuries to blood vessels;

b) phagocytosis, carried out by leukocytes capable of amoeboid movement and phagocytosis;

V) immune protection, carried out by antibodies.

Blood clotting- a complex enzymatic process involving the transfer of soluble protein in blood plasma fibrinogen into insoluble protein fibrin, forming the basis of a blood clot - blood clot The blood clotting process is triggered by the release of an active enzyme from platelets destroyed during injury. thromboplastin, which, in the presence of calcium ions and vitamin K, through a series of intermediate substances, leads to the formation of fibrin filamentous protein molecules. Red blood cells are retained in the network formed by fibrin fibers, resulting in the formation of a blood clot. Drying and shrinking, it turns into a crust that prevents blood loss.

Phagocytosis carried out by certain types of leukocytes that are capable of moving with the help of pseudopods to places where cells and tissues of the body are damaged, where microorganisms are found. Having approached and then pressed against the microbe, the leukocyte absorbs it into the cell, where it is digested under the influence of lysosome enzymes.

Immune protection carried out thanks to the ability of protective proteins - antibodies- recognize foreign material that has entered the body and induce the most important immunophysiological mechanisms aimed at its neutralization. Foreign material can be protein molecules on the surface of microbial cells or foreign cells, tissues, surgically transplanted organs, or changed cells of one's own body (for example, cancerous ones).

Based on their origin, they distinguish between innate and acquired immunity.

Congenital (hereditary, or species) immunity is predetermined genetically and is determined by biological, hereditary characteristics. This immunity is inherited and is characterized by the immunity of one species of animals and humans to pathogenic agents that cause diseases in other species.

Acquired immunity can be natural or artificial. Natural immunity is immunity to a particular disease obtained by the child’s body as a result of the penetration of mother’s antibodies into the fetus’ body

through the placenta (placental immunity), or acquired as a result of a previous disease (post-infectious immunity).

Artificial immunity can be active and passive. Active artificial immunity is developed in the body after the introduction of a vaccine - a drug containing weakened or killed pathogens of a particular disease. Such immunity is less durable than post-infectious immunity and, as a rule, to maintain it, repeated vaccination is necessary after several years. In medical practice, passive immunization is widely used, when a sick person is injected with therapeutic serums containing ready-made antibodies against this pathogen. Such immunity will persist until the antibodies die (1-2 months).

Blood, woven fluid and lymph - internal Wednesday body For What is more characteristic is the relative constancy of the chemical composition Ava and physical chemical properties, which is achieved by the continuous and coordinated work of many organs. Metabolism between blood and cells occurs through tissue liquid.

Protective: function blood is carried out thanks to coagulation, phagocytosis And immune health look for. There are congenital and acquired y immunity. When acquired immunity can be natural or artificial.

I. What is the relationship between the elements of the internal environment of the human body? 2. What is the role of blood plasma? 3. What is the relationship between the structure of erythro-

cytes with the functions they perform? 4. How the protective function is carried out

5. Give a rationale for the concepts: hereditary, natural and artificial, active and passive immunity.

The body of any animal is extremely complex. This is necessary to maintain homeostasis, that is, constancy. For some, the condition is conditionally constant, while for others, more developed, actual constancy is observed. This means that no matter how the environmental conditions change, the body maintains a stable state of the internal environment. Despite the fact that organisms have not yet fully adapted to living conditions on the planet, the internal environment of the organism plays a crucial role in their life.

The concept of internal environment

The internal environment is a complex of structurally separate areas of the body, under no circumstances, other than mechanical damage, not in contact with the outside world. In the human body, the internal environment is represented by blood, interstitial and synovial fluid, cerebrospinal fluid and lymph. These 5 types of fluids together constitute the internal environment of the body. They are called this for three reasons:

• firstly, they do not come into contact with external environment;
• secondly, these fluids maintain homeostasis;
• thirdly, the environment is an intermediary between cells and the external parts of the body, protecting against external adverse factors.

The importance of the internal environment for the body

The internal environment of the body consists of 5 types of fluids, the main task of which is to maintain a constant level of concentrations nutrients close to the cells, maintaining the same acidity and temperature. Due to these factors, it is possible to ensure the functioning of cells, the most important of which in the body is nothing, since they make up tissues and organs. Therefore, the internal environment of the body is the widest transport system and the area where extracellular reactions occur.

It transports nutrients and carries metabolic products to the site of destruction or excretion. Also, the internal environment of the body transports hormones and mediators, allowing some cells to regulate the work of others. This is the basis of humoral mechanisms that ensure the occurrence of biochemical processes, the overall result of which is homeostasis.

It turns out that the entire internal environment of the body (IEC) is the place where all nutrients and biologically active substances should go. This is an area of ​​the body that should not accumulate metabolic products. And in the basic understanding, VSO is the so-called road along which “couriers” (tissue and synovial fluid, blood, lymph and cerebrospinal fluid) deliver “food” and “building material” and remove harmful metabolic products.

Early internal environment of organisms

All representatives of the animal kingdom evolved from single-celled organisms. Their only component of the internal environment of the body was the cytoplasm. From the external environment it was limited by the cell wall and the cytoplasmic membrane. Then further development animals followed the principle of multicellularity. In coelenterate organisms there was a cavity separating the cells and the external environment. It was filled with hydrolymph, in which nutrients and products of cellular metabolism were transported. This type of internal environment was present in flatworms and coelenterates.

Development of the internal environment

In animal classes roundworms, arthropods, mollusks (with the exception of cephalopods) and insects, the internal environment of the body consists of other structures. These are vessels and areas of an open channel through which hemolymph flows. Her main feature is the acquisition of the ability to transport oxygen through hemoglobin or hemocyanin. In general, such an internal environment is far from perfect, which is why it has developed further.

Perfect indoor environment

A perfect internal environment is a closed system, which excludes the possibility of fluid circulation through isolated areas of the body. This is how the bodies of representatives of the classes of vertebrates, annelids and cephalopods are arranged. Moreover, it is most perfect in mammals and birds, which, to support homeostasis, also have a 4-chambered heart, which provides them with warm-bloodedness.

The components of the internal environment of the body are as follows: blood, lymph, joint and tissue fluid, cerebrospinal fluid. It has its own walls: the endothelium of arteries, veins and capillaries, lymphatic vessels, the joint capsule and ependymocytes. On the other side of the internal environment lie the cytoplasmic membranes of the cells with which it is in contact, also included in the BSO.

Blood

The internal environment of the body is partly formed by blood. It is a liquid that contains formed elements, proteins and some elementary substances. A lot of enzymatic processes take place here. But the main function of blood is transport, especially oxygen to cells and carbon dioxide from them. Therefore, the largest proportion of formed elements in the blood are erythrocytes, platelets, and leukocytes. The former are involved in the transport of oxygen and carbon dioxide, although they can also play an important role in immune reactions due to reactive oxygen species.

Leukocytes in the blood are completely occupied only with immune reactions. They participate in the immune response, regulate its strength and completeness, and also store information about antigens with which they have previously been in contact. Since the internal environment of the body is partly formed by blood, which plays the role of a barrier between areas of the body in contact with the external environment and cells, the immune function of blood is second in importance after transport. At the same time, it requires the use of both formed elements and plasma proteins.

The third important function of blood is hemostasis. This concept combines several processes that are aimed at preserving the liquid consistency of the blood and covering defects in the vascular wall when they appear. The hemostasis system ensures that the blood flowing through the vessels remains liquid until the damaged vessel needs to be closed. Moreover, the internal environment of the human body will not be affected, although this requires energy expenditure and the involvement of platelets, erythrocytes and plasma factors of the coagulation and anticoagulation system.

Blood proteins

The second part of the blood is liquid. It consists of water in which proteins, glucose, carbohydrates, lipoproteins, amino acids, vitamins with their carriers and other substances are evenly distributed. Among the proteins, high molecular weight and low molecular weight are distinguished. The first are represented by albumins and globulins. These proteins are responsible for the functioning of the immune system, maintaining plasma oncotic pressure, and the functioning of the coagulation and anticoagulation systems.

Carbohydrates dissolved in the blood act as transported energy-intensive substances. This is a nutrient substrate that must enter the intercellular space, from where it will be captured by the cell and processed (oxidized) in its mitochondria. The cell will receive the energy necessary for the operation of systems responsible for the synthesis of proteins and the performance of functions for the benefit of the entire organism. At the same time, amino acids, also dissolved in the blood plasma, also penetrate the cell and serve as a substrate for protein synthesis. The latter is a tool for the cell to realize its hereditary information.

The role of blood plasma lipoproteins

Another important source of energy, in addition to glucose, is triglyceride. This is fat that must be broken down and become an energy carrier for muscle tissue. It is she who, for the most part, is able to process fats. By the way, they contain much more energy than glucose, and therefore are able to provide muscle contraction for a much longer period than glucose.

Fats are transported into cells using membrane receptors. Fat molecules absorbed in the intestine are first combined into chylomicrons and then enter the intestinal veins. From there, chylomicrons pass to the liver and enter the lungs, where they form low-density lipoproteins. The latter are transport forms in which fats are delivered through the blood into the intercellular fluid to muscle sarcomeres or smooth muscle cells.

Also, blood and intercellular fluid, together with lymph, which make up the internal environment of the human body, transport metabolic products of fats, carbohydrates, and proteins. They are partially contained in the blood, which carries them to the site of filtration (kidney) or disposal (liver). It is obvious that these biological fluids, which are the environments and compartments of the body, play a vital role in the life of the body. But much more important is the presence of a solvent, that is, water. Only thanks to it can substances be transported and cells exist.

Intercellular fluid

It is believed that the composition of the internal environment of the body is approximately constant. Any fluctuations in the concentration of nutrients or metabolic products, changes in temperature or acidity lead to dysfunction. Sometimes they can lead to death. By the way, it is acidity disorders and acidification of the internal environment of the body that is the fundamental and most difficult to correct dysfunction.

This is observed in cases of polyarganic insufficiency, when acute liver and kidney failure develops. These organs are designed to utilize acidic metabolic products, and when this does not happen, there is an immediate threat to the patient’s life. Therefore, in reality, all components of the internal environment of the body are very important. But much more important is the performance of organs, which also depend on the VSO.

It is the intercellular fluid that reacts first to changes in the concentrations of nutrients or metabolic products. Only then does this information enter the blood through mediators secreted by the cells. The latter supposedly transmit a signal to cells in other areas of the body, urging them to take action to correct the problems that have arisen. Bye this system is the most effective of all those represented in the biosphere.

Lymph

Lymph is also the internal environment of the body, the functions of which are limited to the distribution of leukocytes throughout the body and the removal of excess fluid from the interstitial space. Lymph is a fluid containing low and high molecular weight proteins, as well as some nutrients.

It is drained from the interstitial space through tiny vessels that collect and form lymph nodes. Lymphocytes actively multiply in them, playing an important role in the implementation of immune reactions. From the lymphatic vessels it collects into the thoracic duct and flows into the left venous angle. Here the fluid returns to the bloodstream.

Synovial fluid and cerebrospinal fluid

Synovial fluid is a variant of the intercellular fluid fraction. Since cells cannot penetrate into the articular capsule, the only way to nourish the articular cartilage is the synovial cartilage. All articular cavities are the internal environment of the body, because they are in no way connected to the structures in contact with the external environment.

Also included in the VSO are all the ventricles of the brain along with the cerebrospinal fluid and the subarachnoid space. CSF is already a variant of lymph, since the nervous system does not have its own lymphatic system. Through cerebrospinal fluid, the brain is cleared of metabolic products, but is not nourished by it. The brain is nourished by blood, products dissolved in it and bound oxygen.

Through the blood-brain barrier they penetrate neurons and glial cells, delivering the necessary substances to them. Metabolic products are removed through cerebrospinal fluid and venous system. Moreover, probably the most important function of cerebrospinal fluid is to protect the brain and nervous system from temperature fluctuations and mechanical damage. Since the liquid actively dampens mechanical impacts and shocks, this property is really necessary for the body.

Conclusion

The external and internal environments of the body, despite their structural isolation from each other, are inextricably linked by a functional connection. Namely, the external environment is responsible for the flow of substances into the internal environment, from where it removes metabolic products. And the internal environment transfers nutrients to the cells, removing harmful products from them. In this way, homeostasis, the main characteristic of life, is maintained. This also means that it is virtually impossible to separate the external environment of otragism from the internal one.

The internal environment of the body is blood, lymph and fluid that fills the spaces between cells and tissues. The blood and lymphatic vessels that penetrate all human organs have tiny pores in their walls through which even some blood cells can penetrate. Water, which forms the basis of all fluids in the body, together with organic and inorganic substances dissolved in it, easily passes through the walls of blood vessels. Consequently chemical composition blood plasma (that is, the liquid part of the blood that does not contain cells), lymph and tissue liquids is largely the same. With age, there are no significant changes in the chemical composition of these fluids. At the same time, differences in the composition of these fluids may be associated with the activity of the organs in which these fluids are located.

Blood

Blood composition. Blood is a red, opaque liquid consisting of two fractions - liquid, or plasma, and solid, or cells - blood cells. It is quite easy to separate blood into these two fractions using a centrifuge: the cells are heavier than plasma and in a centrifuge tube they collect at the bottom in the form of a red clot, and a layer of transparent and almost colorless liquid remains above it. This is plasma.

Plasma. The adult human body contains about 3 liters of plasma. In a healthy adult, plasma makes up more than half (55%) of the blood volume, in children it is slightly less.

More than 90% of plasma composition - water, the rest is inorganic salts dissolved in it, as well as organic matter: carbohydrates, carboxylic, fatty acids and amino acids, glycerin, soluble proteins and polypeptides, urea, etc. Together they determine blood osmotic pressure, which in the body is maintained at a constant level so as not to cause harm to the cells of the blood itself, as well as to all other cells of the body: increased osmotic pressure leads to shrinkage of cells, and with reduced osmotic pressure they swell. In both cases, cells may die. Therefore, for the introduction of various drugs into the body and for transfusion of blood-replacing fluids in case of large blood loss, special solutions are used that have exactly the same osmotic pressure as blood (isotonic). Such solutions are called physiological. The simplest physiological solution in composition is a 0.1% solution of sodium chloride NaCl (1 g of salt per liter of water). Plasma is involved in the transport function of blood (transports substances dissolved in it), as well as the protective function, since some proteins dissolved in plasma have an antimicrobial effect.

Blood cells. There are three main types of cells in the blood: red blood cells, or red blood cells, white blood cells, or leukocytes; blood platelets, or platelets. Cells of each of these types perform specific physiological functions, and together they determine the physiological properties of blood. All blood cells are short-lived (the average lifespan is 2 - 3 weeks), therefore, throughout life, special hematopoietic organs are engaged in the production of more and more new blood cells. Hematopoiesis occurs in the liver, spleen and bone marrow, as well as in the lymph glands.

Red blood cells(Fig. 11) are anucleate disc-shaped cells, devoid of mitochondria and some other organelles and adapted for one main function - to be oxygen carriers. The red color of red blood cells is determined by the fact that they carry the protein hemoglobin (Fig. 12), in which the functional center, the so-called heme, contains an iron atom in the form of a divalent ion. Heme is capable of chemically combining with an oxygen molecule (the resulting substance is called oxyhemoglobin) if the partial pressure of oxygen is high. This bond is fragile and is easily destroyed if the partial pressure of oxygen drops. It is on this property that the ability of red blood cells to carry oxygen is based. Once in the lungs, the blood in the pulmonary vesicles finds itself in conditions of increased oxygen tension, and hemoglobin actively captures atoms of this gas, which is poorly soluble in water. But as soon as blood enters working tissues that actively use oxygen, oxyhemoglobin easily gives it away, obeying the “oxygen demand” of the tissues. During active functioning, tissues produce carbon dioxide and other acidic products that exit through the cell walls into the blood. This further stimulates oxyhemoglobin to release oxygen, since the chemical bond between hemoglobin and oxygen is very sensitive to the acidity of the environment. In return, heme attaches a CO 2 molecule to itself, carrying it to the lungs, where this chemical bond is also destroyed, CO 2 is carried out with the current of exhaled air, and hemoglobin is released and is again ready to attach oxygen to itself.

Rice. 10. Red blood cells: a - normal red blood cells in the shape of a biconcave disc; b - wrinkled red blood cells in hypertonic saline solution

If carbon monoxide CO is present in the inhaled air, it enters into a chemical interaction with hemoglobin in the blood, resulting in the formation of a strong substance, methoxyhemoglobin, which does not disintegrate in the lungs. Thus, hemoglobin in the blood is removed from the process of oxygen transfer, tissues do not receive the required amount of oxygen, and the person feels suffocated. This is the mechanism of human poisoning in a fire. A similar effect is exerted by some other instant poisons, which also disable hemoglobin molecules, for example, hydrocyanic acid and its salts (cyanides).

Rice. 11. Spatial model of the hemoglobin molecule

Every 100 ml of blood contains about 12 g of hemoglobin. Each hemoglobin molecule is capable of “carrying” 4 oxygen atoms. The blood of an adult contains a huge number of red blood cells - up to 5 million in one milliliter. Newborns have even more of them - up to 7 million, which means more hemoglobin. If a person lives for a long time in conditions of lack of oxygen (for example, high in the mountains), then the number of red blood cells in his blood increases even more. As the body ages, the number of red blood cells changes in waves, but in general, children have slightly more of them than adults. A decrease in the number of red blood cells and hemoglobin in the blood below normal indicates a serious illness - anemia (anemia). One of the causes of anemia may be a lack of iron in food. Foods rich in iron include: beef liver, apples and some others. In cases of prolonged anemia, it is necessary to take medications containing iron salts.

Along with determining the level of hemoglobin in the blood, the most common clinical blood tests include measuring the erythrocyte sedimentation rate (ESR), or erythrocyte sedimentation reaction (ERS), - these are two equal names for the same test. If you prevent blood clotting and leave it in a test tube or capillary for several hours, then without mechanical shaking, heavy red blood cells will begin to precipitate. The speed of this process in adults ranges from 1 to 15 mm/h. If this indicator is significantly higher than normal, this indicates the presence of a disease, most often inflammatory. In newborns, ESR is 1-2 mm/h. By the age of 3, ESR begins to fluctuate - from 2 to 17 mm/h. In the period from 7 to 12 years, ESR usually does not exceed 12 mm/h.

Leukocytes- white blood cells. They do not contain hemoglobin, so they are not red in color. Main function leukocytes - protect the body from pathogenic microorganisms and toxic substances that have penetrated inside it. Leukocytes are able to move using pseudopodia, like amoebas. This way they can leave the blood capillaries and lymphatic vessels, in which there are also a lot of them, and move towards the accumulation of pathogenic microbes. There they devour microbes, carrying out the so-called phagocytosis.

There are many types of white blood cells, but the most typical are lymphocytes, monocytes and neutrophils. Neutrophils, which, like erythrocytes, are formed in the red bone marrow, are most active in the processes of phagocytosis. Each neutrophil can absorb 20-30 microbes. If the body is invaded by a large foreign body(for example, a splinter), then many neutrophils stick around it, forming a kind of barrier. Monocytes - cells formed in the spleen and liver, also participate in the processes of phagocytosis. Lymphocytes, which are formed mainly in the lymph nodes, are not capable of phagocytosis, but are actively involved in other immune reactions.

1 ml of blood normally contains from 4 to 9 million leukocytes. The ratio between the number of lymphocytes, monocytes and neutrophils is called the blood formula. If a person gets sick, the total number of leukocytes increases sharply, and the blood formula also changes. By its change, doctors can determine what type of microbe the body is fighting.

In a newborn child, the number of white blood cells is significantly (2-5 times) higher than in an adult, but after a few days it decreases to a level of 10-12 million per 1 ml. Starting from the 2nd year of life, this value continues to decrease and reaches typical adult values ​​after puberty. In children, the processes of formation of new blood cells are very active, therefore among the blood leukocytes in children there are significantly more young cells than in adults. Young cells differ in their structure and functional activity from mature ones. After 15-16 years, the blood formula acquires the parameters characteristic of adults.

Platelets- the smallest formed elements of blood, the number of which reaches 200-400 million in 1 ml. Muscular work and other types of stress can increase the number of platelets in the blood several times (this, in particular, is the danger of stress for older people: after all, blood clotting depends on platelets, including the formation of blood clots and blockage of small vessels in the brain and heart muscles). Place of platelet formation - red Bone marrow and spleen. Their main function is to ensure blood clotting. Without this function, the body becomes vulnerable at the slightest injury, and the danger lies not only in the fact that a significant amount of blood is lost, but also in the fact that any open wound- this is a gateway for infection.

If a person is injured, even shallowly, the capillaries are damaged, and platelets along with the blood end up on the surface. Here they are affected by two the most important factors- low temperature (much lower than 37 ° C inside the body) and plenty of oxygen. Both of these factors lead to the destruction of platelets, and from them substances are released into the plasma that are necessary for the formation of a blood clot - a thrombus. In order for a blood clot to form, the blood must be stopped by squeezing a large vessel if blood is pouring heavily from it, since even the process of thrombus formation that has begun will not go to completion if new and new portions of blood with a high temperature are constantly entering the wound and not yet destroyed platelets.

To prevent blood from clotting inside the vessels, it contains special anti-clotting substances - heparin, etc. As long as the vessels are not damaged, there is a balance between substances that stimulate and inhibit coagulation. Damage to blood vessels leads to disruption of this balance. In old age and with increasing disease, this balance in a person is also disturbed, which increases the risk of blood clotting in small vessels and the formation of a life-threatening blood clot.

Age-related changes in platelet function and blood coagulation were studied in detail by A. A. Markosyan, one of the founders of age-related physiology in Russia. It was found that in children, coagulation occurs more slowly than in adults, and the resulting clot has a looser structure. These studies led to the formation of the concept of biological reliability and its increase in ontogenesis.

The creator provided complex mechanism in the form of a living being.

Every organ in it works according to a clear pattern.

In protecting a person from changes in others, maintaining homeostasis and stability of each element within important role belongs to the internal environment of the organism - bodies that are separated from the world without points of contact with it belong to it.

No matter how complex the internal organization of an animal is, they can be multicellular or multicellular, but in order for their life to be realized and continue in the future, certain conditions are needed. Evolutionary development has adapted them and provided them with such conditions, in which they feel comfortable for existence and reproduction.

It is believed that life began in sea water; it served the first living formations as a kind of home, their environment of existence.

In the course of numerous natural, complication of cellular structures, some part of them began to be separated and isolated from the outside world. These cells ended up in the middle of the animal, this improvement allowed living organisms to leave the ocean and begin to adapt to the surface of the earth.

Surprisingly, the amount of salt in percentage in the World Ocean is equal to the internal environment, these include sweat, tissue fluid, which is presented in the form:

• blood
• interstitial and synovial fluid
• lymph
• cerebrospinal fluid

The reasons why the habitat of isolated elements was named this way:

• they are separated from external life
• the composition maintains homeostasis, that is, a constant state of substances
• play an intermediary role in the connection of the entire cellular system, transfer the necessary vitamins for life, protect against unfavorable penetration

How consistency is created

The internal environment of the body includes urine, lymph, and they contain not only various salts, but also substances consisting of:

• proteins
• Sahara
• fat
• hormones

The organization of any creature living on the planet is created in the amazing performance of each organ. They create a kind of circulation of vital products, which are secreted inside in the required quantity and in return receive the desired composition of substances, while creating the constancy of the constituent elements, maintaining homeostasis.

The work occurs according to a strict pattern, if the blood cells release liquid composition, it enters tissue fluids. Its further movement begins through the capillaries and veins, and the required substance is constantly distributed into which gap to supply the intercellular connections.

The spaces that create pathways for the entry of peculiar water are located between the walls of the capillaries. The heart muscle contracts, from which blood is formed, and the salts and nutrients contained in it move along the passages provided to them.

There is an unambiguous connection of fluid bodies and contact of extracellular fluid with blood cells, the cerebrospinal substance, which are present around the spinal cord and brain.

This process proves the centralized regulation of liquid compositions. The tissue type of matter envelops the cellular elements and is their home in which they have to live and develop. To achieve this, constant renewal occurs in the lymphatic system. The mechanism for collecting liquid in the vessels works, there is the largest one, movement occurs along it and the mixture enters the general river of the bloodstream and mixes in it.

The constancy of the circulation of fluids has been created with various functions, but with the sole purpose of fulfilling the organic rhythm of life of an amazing instrument - which is an animal on planet Earth.

What does their habitat mean for organs?

All fluids, which are the internal environment, perform their functions, maintain a constant level and concentrate nutrients around the cells, maintain the same acidity and temperature.

The components of all organs and tissues belong to cells, the most important elements complex animal mechanism, their uninterrupted operation, life ensures internal composition, substances.

It represents a kind of transport system, the volume of areas through which extracellular reactions occur.

Her service includes the movement of substances serving for, carrying liquid elements to destroyed points, areas where they are removed.

In addition, the responsibility of the internal habitat is to provide hormones and mediators so that the regulation of actions between cells occurs. For the humoral mechanism, the habitat area is the basis for normal biochemical processes to take place and to ensure the overall result of strong constancy in the form of homeostasis.

Schematically, such a procedure consists of the following conclusions:

• VSO represents the places where nutrients and biological substances are collected
• accumulation of metabolites is excluded
• is vehicle to provide food and building material to the body
• protects against malicious

Based on the statements of scientists, the importance of liquid tissues following their own paths and working for the well-being of the animal organism becomes clear.

How does habitation originate?

The animal world appeared on Earth thanks to single-celled organisms.

They lived in a house consisting of one element - cytoplasm.

It was separated from the outside world by a wall consisting of a cell and a membrane of cytoplasm.

There are also coelenterate creatures, the peculiarity of which is the separation of cells from the external environment using a cavity.

The road for movement is hydrolymph; it transports nutrients along with products from the corresponding cells. Creatures belonging to flatworms and coelenterates have similar insides.

Development of a separate system

In the community of roundworms, arthropods, mollusks, and insects, a special internal structure. It consists of vascular conductors and areas through which hemolymph flows. With its help, oxygen is transported, which is part of hemoglobin and hemocyanin. This internal mechanism was imperfect and its development continued.

Improving the transport route

A closed system consists of a good internal environment; it is impossible for liquid substances to move through it on separate objects. Creatures belonging to:

• vertebrates
• ringworms
• cephalopods

Nature has given the class of mammals and birds the most perfect mechanism; the heart muscle from four chambers helps them maintain homeostasis; it retains the heat of the blood flow, which is why they are classified as warm-blooded. With the help of many years of improvement of the functioning of a living machine, a special internal composition of blood, lymph, joint and tissue fluids, and cerebrospinal fluid was formed.

With the following insulators:

• endothelial arteries
• venous
• capillary
• lymphatic
• ependymocytes

There is another side, consisting of cytoplasmic cell membranes, which communicates with intercellular substances included in the BSO family.

Blood composition

Everyone has seen the red composition, which is the basis of our body. From time immemorial, blood has been endowed with power, poets have dedicated odes and philosophized on this topic. Hippocrates even attributed healing properties to this substance, prescribing it to those with a sick soul, believing that it was contained in the blood. This amazing fabric that it truly is has many jobs to do.

Among which, thanks to its circulation, the following functions are carried out:

• respiratory – direct and saturate all organs and tissues with oxygen, redistribute the composition of carbon dioxide
• nutritious - move the accumulation of nutrients stuck to the intestines into the body. This method supplies water, amino acids, glucose, fats, vitamins, and minerals.
• excretory – deliver representatives of the end products of creatines, urea, from one to another, which ultimately remove them from the body or destroy them
• thermoregulatory - transported by blood plasma from skeletal muscles, liver to skin, which consume heat. In hot weather, skin pores can expand, give off excess heat, and turn red. In the cold, windows are closed, which can increase blood flow and give off heat, the skin becomes bluish
• regulatory - with the help of blood cells, water in tissues is regulated, its amount is increased or decreased. Acids and alkalis are distributed evenly throughout the tissues. Transfer of hormones and active substances from the place where they were born to the points that are targets, once on it the substance will arrive at its destination
• protective - these bodies provide protection against blood loss during injury. They form a kind of plug, this process is simply called - the blood has clotted. This property prevents bacterial, viral, fungal and other unfavorable formations from penetrating into the bloodstream. For example, with the help of leukocytes, which serve as a barrier to toxins, molecules that are pathogenic, when antibodies and phagocytosis appear

An adult's body contains about five liters of blood. All of it is distributed among objects and fulfills its role. One part is intended to circulate through the conductors, the other is located under the skin, enveloping the spleen. But it is there, as if in storage, and when an urgent need arises, it immediately comes into play.

A person is busy running, doing physical activity, or is injured, the blood connects to its functions, compensating for its need in a certain area.

The blood composition includes:

• plasma – 55%
• formed elements – 45%

Many people depend on plasma production processes. It contains in its community 90% water and 10% material components.

They are included in the main work:

• Albumin retains the required amount of water
• globulins make up antibodies
• fibrinogens cause blood to clot
• amino acids are transported through tissues

Plasma contains a whole list of inorganic salts and useful substances:

• potassium
• calcium
• phosphorus

The group of formed blood elements includes the following content:

• red blood cells
• leukocytes
• platelets

Blood transfusions have long been used in medicine for people who have lost a sufficient amount of it from injury or surgical intervention. Scientists have created a whole doctrine on blood, its groups and its compatibility in the human body.

What barriers does the body protect?

The body of a living being is protected by its internal environment.

This responsibility is assumed by leukocytes with the help of phagocytic cells.

Substances such as antibodies and antitoxins also act as protectors.

They are produced by leukocytes and various tissues when an infectious disease strikes a person.

With the help of protein substances (antibodies), microorganisms stick together, combine, and are destroyed.

Microbes, getting inside the animal, release poison, then the antitoxin comes to the rescue and neutralizes it. But the work of these elements has a certain specificity, and their action is aimed only at the unfavorable formation due to which it occurred.

The ability of antibodies to take root in the body and stay there for a long time creates protection for people against infectious diseases. Same property human body determined by his weak or strong immune system.

What is a strong body?

The health of a person or animal depends on immunity.

How susceptible is he to infection by infectious diseases?

One person will not be affected by a raging influenza epidemic, while another may get sick from all of them even without outbreaks.

Resistance to foreign genetic information from various factors is important; this task falls on the work.

He, like a fighter on the battlefield, defends his homeland, his home, and the immune system destroys foreign cells and substances that have entered the body. Maintains genetic homeostasis during ontogenesis.

When cells split, they divide, their mutation is possible, which can result in formations that have been changed by the genome. Mutated cells appear in the creature, they are capable of causing some harm, but with strong immune system this will not happen, resilience will destroy enemies.

Ability to defend against infectious diseases divided into:

• natural, developed properties obtained from the body
• artificial, when drugs are injected into a person to prevent infection

Natural immunity to diseases tends to appear in a person at birth. Sometimes this property is acquired after suffering. The artificial method includes active and passive abilities to fight microbes.

Transport of metabolic products

Blood

Blood functions:

Transport: transfer of oxygen from the lungs to the tissues and carbon dioxide from the tissues to the lungs; delivery of nutrients, vitamins, minerals and water from the digestive organs to the tissues; removal of metabolic end products, excess water and mineral salts from tissues.

Protective: participation in cellular and humoral mechanisms of immunity, in blood clotting and stopping bleeding.

Regulatory: temperature regulation, water-salt metabolism between blood and tissues, transfer of hormones.

Homeostatic: maintaining the stability of homeostasis indicators (pH, osmotic pressure (pressure exerted by a solute through the movement of its molecules), etc.).

Rice. 1. Blood composition

Blood element	Structure/composition	Function
plasma	yellowish translucent liquid made from water, minerals and organic matter	transport: nutrients from the digestive system to the tissues, metabolic products and excess water from the tissues to the organs of the excretory system;
blood clotting (fibrinogen protein)	red blood cells	red blood cells: biconcave shape;
contain the protein hemoglobin;	no kernel	oxygen transport from lungs to tissues;
transport of carbon dioxide from tissues to lungs;	enzymatic - transfer enzymes;	protective - bind toxic substances;

nutritional - amino acid transport;

take part in blood clotting;

maintain a constant blood pH leukocytes white blood cells: have a nucleus;.

various shapes and sizes; some are capable of amoeboid movement; able to penetrate the capillary wall;

capable of phagocytosis cellular and humoral immunity; destruction of dead cells; enzymatic function (contain enzymes for the breakdown of proteins, fats, carbohydrates); take part in blood clotting

platelets

blood platelets: the ability to stick to the walls of damaged vessels (adhesion) and glue them together;

capable of combining (aggregation)

blood clotting (coagulation);

tissue regeneration (growth factors are released);

immune defense

The first component of the internal environment of the body - blood - has a liquid consistency and red color. The red color of blood comes from hemoglobin contained in red blood cells. makes up about 55% of all proteins contained in plasma; synthesized in the liver.

Albumin function:

transport of substances poorly soluble in water (bilirubin, fatty acids, lipid hormones and some drugs (for example, penicillin).

Globulins- globular blood proteins having a higher molecular weight and solubility in water than albumins; synthesized in the liver and immune system.

Functions of globulins:

immune protection;

participate in blood clotting;

transport of oxygen, iron, hormones, vitamins.

Fibrinogen- a blood protein produced in the liver.

Function of fibrinogen:

blood clotting; fibrinogen is capable of converting into the insoluble protein fibrin and forming a blood clot.

Nutrients are also dissolved in plasma: amino acids, glucose (0.11%), lipids. The end products of metabolism also enter the plasma: urea, uric acid etc. Plasma also contains various hormones, enzymes and other biologically active substances.

Plasma minerals make up about 1% (cations Na+, K+, Ca2+, C anions l–, NSO–3, NPO2−4).

Blood serum- blood plasma devoid of fibrinogen.

Serums are obtained either by natural clotting of plasma (the remaining liquid part is serum), or by stimulating the conversion of fibrinogen into insoluble fibrin - deposition- calcium ions.

Blood, lymph, and tissue fluid form the internal environment of the body. From blood plasma penetrating through the walls of capillaries, tissue fluid is formed, which washes the cells. There is a constant exchange of substances between tissue fluid and cells. The circulatory and lymphatic systems provide humoral communication between organs, combining metabolic processes into a common system. The relative constancy of the physicochemical properties of the internal environment contributes to the existence of body cells in fairly constant conditions and reduces the influence of the external environment on them. The constancy of the internal environment - homeostasis - of the body is supported by the work of many organ systems, which ensure self-regulation of vital processes, interaction with the environment, the supply of substances necessary for the body and remove decay products from it.

1. Composition and functions of blood

Blood performs the following functions: transport, heat distribution, regulatory, protective, participates in excretion, maintains the constancy of the internal environment of the body.

The adult body contains about 5 liters of blood, on average 6-8% of body weight. Part of the blood (about 40%) does not circulate through the blood vessels, but is located in the so-called blood depot (in the capillaries and veins of the liver, spleen, lungs and skin). The volume of circulating blood can change due to changes in the volume of deposited blood: during muscular work, during blood loss, under conditions of low atmospheric pressure, blood from the depot is released into the bloodstream. Loss 1/3- 1/2 blood volume can lead to death.

Blood is an opaque red liquid consisting of plasma (55%) and suspended cells and formed elements (45%) - red blood cells, leukocytes and platelets.

1.1. Blood plasma

Blood plasma contains 90-92% water and 8-10% inorganic and organic substances. Inorganic substances make up 0.9-1.0% (ions Na, K, Mg, Ca, CI, P, etc.). An aqueous solution, which in terms of salt concentration corresponds to blood plasma, is called physiological solution. It can be introduced into the body if there is a lack of fluid. Among the organic substances in plasma, 6.5-8% are proteins (albumin, globulins, fibrinogen), about 2% are low molecular weight organic substances (glucose - 0.1%, amino acids, urea, uric acid, lipids, creatinine). Proteins, along with mineral salts, maintain acid-base balance and create a certain osmotic pressure in the blood.

1.2. Formed elements of blood

1 mm of blood contains 4.5-5 million. red blood cells. These are anucleate cells, having the shape of biconcave disks with a diameter of 7-8 microns, a thickness of 2-2.5 microns (Fig. 1). This cell shape increases the surface area for the diffusion of respiratory gases, and also makes red blood cells capable of reversible deformation when passing through narrow curved capillaries. In adults, red blood cells are formed in the red bone marrow of the spongy bones and, when released into the bloodstream, lose their nucleus. The circulation time in the blood is about 120 days, after which they are destroyed in the spleen and liver. Red blood cells can also be destroyed by tissues of other organs, as evidenced by the disappearance of “bruises” (subcutaneous hemorrhages).

Red blood cells contain protein - hemoglobin, consisting of protein and non-protein parts. Non-protein part (heme) contains iron ion. Hemoglobin forms a weak connection with oxygen in the capillaries of the lungs - oxyhemoglobin. This compound is different in color from hemoglobin, so arterial blood(oxygenated blood) has a bright scarlet color. Oxyhemoglobin that gives up oxygen in tissue capillaries is called restored. He is in venous blood(oxygen-poor blood), which has a darker color than arterial blood. In addition, venous blood contains an unstable compound of hemoglobin with carbon dioxide - carbhemoglobin. Hemoglobin can combine not only with oxygen and carbon dioxide, but also with other gases, such as carbon monoxide, forming a strong compound carboxyhemoglobin. Carbon monoxide poisoning causes asphyxiation. When the amount of hemoglobin in red blood cells decreases or the number of red blood cells in the blood decreases, anemia occurs.

Leukocytes(6-8 thousand/mm of blood) - nuclear cells 8-10 microns in size, capable of independent movements. There are several types of leukocytes: basophils, eosinophils, neutrophils, monocytes and lymphocytes. They are formed in the red bone marrow, lymph nodes and spleen, and are destroyed in the spleen. The lifespan of most leukocytes is from several hours to 20 days, and that of lymphocytes is 20 years or more. In acute infectious diseases, the number of leukocytes increases rapidly. Passing through the walls of blood vessels, neutrophils phagocytize bacteria and tissue breakdown products and destroy them with their lysosomal enzymes. Pus consists mainly of neutrophils or their remains. I.I. Mechnikov named such leukocytes phagocytes, and the very phenomenon of absorption and destruction of foreign bodies by leukocytes is phagocytosis, which is one of the body’s protective reactions.

Rice. 1. Human blood cells:

A- red blood cells, b- granular and non-granular leukocytes , V - platelets

Increase in number eosinophils observed in allergic reactions and helminthic infestations. Basophils produce biologically active substances - heparin and histamine. Basophil heparin prevents blood clotting at the site of inflammation, and histamine dilates capillaries, which promotes resorption and healing.

Monocytes- the largest leukocytes; their ability to phagocytosis is most pronounced. They become of great importance in chronic infectious diseases.

Distinguish T lymphocytes(formed in the thymus gland) and B lymphocytes(formed in red bone marrow). They perform specific functions in immune reactions.

Platelets (250-400 thousand/mm3) are small anucleate cells; participate in blood clotting processes.

Internal environment of the body

The vast majority of cells in our body function in a liquid environment. From it, cells receive the necessary nutrients and oxygen, and they secrete the products of their vital activity into it. Only upper layer keratinized, essentially dead, skin cells border on air and protect the liquid internal environment from drying out and other changes. The internal environment of the body consists of tissue fluid, blood and lymph.

Tissue fluid is a liquid that fills small spaces between the cells of the body. Its composition is close to blood plasma. When blood moves through capillaries, plasma components constantly penetrate through their walls. This creates tissue fluid that surrounds the cells of the body. From this fluid, cells absorb nutrients, hormones, vitamins, minerals, water, oxygen, and release carbon dioxide and other waste products into it. Tissue fluid is constantly replenished by substances penetrating from the blood and turns into lymph, which enters the blood through lymphatic vessels. The volume of tissue fluid in humans is 26.5% of body weight.

Lymph(lat. lympha - pure water, moisture) is a fluid circulating in the lymphatic system of vertebrates. It is a colorless, transparent liquid, similar in chemical composition to blood plasma. The density and viscosity of lymph is less than that of plasma, pH 7.4 - 9. Lymph flowing from the intestines after eating a meal rich in fat is milky white and opaque. Lymph contains no red blood cells, but many lymphocytes, a small number of monocytes and granular leukocytes. Lymph does not contain platelets, but it can clot, although more slowly than blood. Lymph is formed due to the constant flow of fluid into tissues from plasma and its transition from tissue spaces to lymphatic vessels. Most lymph is produced in the liver. Lymph moves due to the movement of organs, contraction of body muscles and negative pressure in the veins. Lymph pressure is 20 mm of water. Art., can increase to 60 mm of water. Art. The volume of lymph in the body is 1 - 2 liters.

Blood is a liquid connective (support-trophic) tissue, the cells of which are called formed elements (erythrocytes, leukocytes, platelets), and the intercellular substance is called plasma.

Main functions of blood:

• transport(transfer of gases and biologically active substances);
• trophic(nutrient delivery);
• excretory(removal of metabolic end products from the body);
• protective(protection from foreign microorganisms);
• regulatory(regulation of organ functions due to the active substances that it carries).

The total amount of blood in the body of an adult is normally 6 - 8% of body weight and approximately equal to 4.5 - 6 liters. At rest, the vascular system contains 60-70% of the blood. This is circulating blood. The other part of the blood (30 - 40%) is contained in special blood depots(liver, spleen, subcutaneous fatty tissue). This is deposited, or reserve, blood.

The liquids that make up the internal environment have a constant composition - homeostasis . It is the result of a mobile equilibrium of substances, some of which enter the internal environment, while others leave it. Due to the small difference between the intake and consumption of substances, their concentration in the internal environment continuously fluctuates from... to.... Thus, the amount of sugar in the blood of an adult can range from 0.8 to 1.2 g/l. More or less than normal amounts of certain blood components usually indicate the presence of a disease.

Examples of homeostasis

Consistency of blood glucose levels	Constancy of salt concentration	Constancy of body temperature
The normal blood glucose concentration is 0.12%. After eating, the concentration increases slightly, but quickly returns to normal thanks to the hormone insulin, which lowers the concentration of glucose in the blood. In diabetes mellitus, insulin production is impaired, so patients must take artificially synthesized insulin. Otherwise, the glucose concentration may reach life-threatening values.	The normal concentration of salts in human blood is 0.9%. The saline solution (0.9% sodium chloride solution) used for intravenous infusions, washing the nasal mucosa, etc.	The normal human body temperature (when measured in the armpit) is 36.6 ºС; a temperature change of 0.5-1 ºС during the day is also considered normal. However, a significant change in temperature poses a threat to life: a decrease in temperature to 30 ºС causes a significant slowdown in biochemical reactions in the body, and at temperatures above 42 ºС protein denaturation occurs.

The phrase “internal environment of the body” appeared thanks to a French physiologist who lived in the 19th century. In his works, he emphasized that a necessary condition for the life of an organism is to maintain constancy in the internal environment. This position became the basis for the theory of homeostasis, which was formulated later (in 1929) by the scientist Walter Cannon.

Homeostasis - relative dynamic constancy of the internal environment, as well as some staticity physiological functions. The internal environment of the body is formed by two fluids - intracellular and extracellular. The fact is that each cell of a living organism performs a specific function, so it needs a constant supply of nutrients and oxygen. She also feels the need to constantly remove waste products. The necessary components can penetrate the membrane only in a dissolved state, which is why each cell is washed by tissue fluid, which contains everything necessary for its life. It belongs to the so-called extracellular fluid, and accounts for 20 percent of body weight.

The internal environment of the body, consisting of extracellular fluid, contains:

• lymph (component of tissue fluid) - 2 l;
• blood - 3 l;
• interstitial fluid - 10 l;
• transcellular fluid - about 1 liter (it includes cerebrospinal, pleural, synovial, intraocular fluids).

They all have different composition and differ in their functional properties. Moreover, the internal environment may have a small difference between the consumption of substances and their intake. Because of this, their concentration constantly fluctuates. For example, the amount of sugar in the blood of an adult can range from 0.8 to 1.2 g/l. If the blood contains more or less of certain components than necessary, this indicates the presence of a disease.

As already noted, the internal environment of the body contains blood as one of its components. It consists of plasma, water, proteins, fats, glucose, urea and mineral salts. Its main location is (capillaries, veins, arteries). Blood is formed due to the absorption of proteins, carbohydrates, fats, and water. Its main function is the relationship of organs with the external environment, delivery of necessary substances to organs, and removal of decay products from the body. It also performs protective and humoral functions.

Tissue fluid consists of water and nutrients dissolved in it, CO 2, O 2, as well as dissimilation products. It is located in the spaces between tissue cells and is formed due to Tissue fluid is intermediate between blood and cells. It transfers O2, mineral salts,

Lymph consists of water and dissolved in it. It is located in the lymphatic system, which consists of lymphatic capillaries, vessels merged into two ducts and flowing into the vena cava. It is formed by tissue fluid in sacs that are located at the ends of lymphatic capillaries. The main function of lymph is to return tissue fluid to the bloodstream. In addition, it filters and disinfects tissue fluid.

As we see, the internal environment of the body is a set of physiological, physico-chemical, respectively, and genetic conditions that affect the viability of a living being.

The internal environment of the body is blood, lymph and fluid that fills the spaces between cells and tissues. The blood and lymphatic vessels that penetrate all human organs have tiny pores in their walls through which even some blood cells can penetrate. Water, which forms the basis of all fluids in the body, together with organic and inorganic substances dissolved in it, easily passes through the walls of blood vessels. As a result, the chemical composition of blood plasma (that is, the liquid part of the blood that does not contain cells), lymph and tissue liquids is largely the same. With age, there are no significant changes in the chemical composition of these fluids. At the same time, differences in the composition of these fluids may be associated with the activity of the organs in which these fluids are located.

Blood

Blood composition. Blood is a red, opaque liquid consisting of two fractions - liquid, or plasma, and solid, or cells - blood cells. It is quite easy to separate blood into these two fractions using a centrifuge: the cells are heavier than plasma and in a centrifuge tube they collect at the bottom in the form of a red clot, and a layer of transparent and almost colorless liquid remains above it. This is plasma.

Plasma. The adult human body contains about 3 liters of plasma. In a healthy adult, plasma makes up more than half (55%) of the blood volume, in children it is slightly less.

More than 90% of plasma composition - water, the rest is inorganic salts dissolved in it, as well as organic matter: carbohydrates, carboxylic, fatty acids and amino acids, glycerin, soluble proteins and polypeptides, urea, etc. Together they determine blood osmotic pressure, which in the body is maintained at a constant level so as not to cause harm to the cells of the blood itself, as well as to all other cells of the body: increased osmotic pressure leads to shrinkage of cells, and with reduced osmotic pressure they swell. In both cases, cells may die. Therefore, for the introduction of various drugs into the body and for transfusion of blood-replacing fluids in case of large blood loss, special solutions are used that have exactly the same osmotic pressure as blood (isotonic). Such solutions are called physiological. The simplest physiological solution in composition is a 0.1% solution of sodium chloride NaCl (1 g of salt per liter of water). Plasma is involved in the transport function of blood (transports substances dissolved in it), as well as the protective function, since some proteins dissolved in plasma have an antimicrobial effect.

Blood cells. There are three main types of cells in the blood: red blood cells, or red blood cells, white blood cells, or leukocytes; blood platelets, or platelets. Cells of each of these types perform specific physiological functions, and together they determine the physiological properties of blood. All blood cells are short-lived (the average lifespan is 2 - 3 weeks), therefore, throughout life, special hematopoietic organs are engaged in the production of more and more new blood cells. Hematopoiesis occurs in the liver, spleen and bone marrow, as well as in the lymph glands.

Red blood cells(Fig. 11) are anucleate disc-shaped cells, devoid of mitochondria and some other organelles and adapted for one main function - to be oxygen carriers. The red color of red blood cells is determined by the fact that they carry the protein hemoglobin (Fig. 12), in which the functional center, the so-called heme, contains an iron atom in the form of a divalent ion. Heme is capable of chemically combining with an oxygen molecule (the resulting substance is called oxyhemoglobin) if the partial pressure of oxygen is high. This bond is fragile and is easily destroyed if the partial pressure of oxygen drops. It is on this property that the ability of red blood cells to carry oxygen is based. Once in the lungs, the blood in the pulmonary vesicles finds itself in conditions of increased oxygen tension, and hemoglobin actively captures atoms of this gas, which is poorly soluble in water. But as soon as blood enters working tissues that actively use oxygen, oxyhemoglobin easily gives it away, obeying the “oxygen demand” of the tissues. During active functioning, tissues produce carbon dioxide and other acidic products that exit through the cell walls into the blood. This further stimulates oxyhemoglobin to release oxygen, since the chemical bond between hemoglobin and oxygen is very sensitive to the acidity of the environment. In return, heme attaches a CO 2 molecule to itself, carrying it to the lungs, where this chemical bond is also destroyed, CO 2 is carried out with the current of exhaled air, and hemoglobin is released and is again ready to attach oxygen to itself.

Rice. 10. Red blood cells: a - normal red blood cells in the shape of a biconcave disc; b - wrinkled red blood cells in hypertonic saline solution

If carbon monoxide CO is present in the inhaled air, it enters into a chemical interaction with hemoglobin in the blood, resulting in the formation of a strong substance, methoxyhemoglobin, which does not disintegrate in the lungs. Thus, hemoglobin in the blood is removed from the process of oxygen transfer, tissues do not receive the required amount of oxygen, and the person feels suffocated. This is the mechanism of human poisoning in a fire. Some other instant poisons have a similar effect, which also disable hemoglobin molecules, for example hydrocyanic acid and its salts (cyanides).

Rice. 11. Spatial model of the hemoglobin molecule

Every 100 ml of blood contains about 12 g of hemoglobin. Each hemoglobin molecule is capable of “carrying” 4 oxygen atoms. The blood of an adult contains a huge number of red blood cells - up to 5 million in one milliliter. Newborns have even more of them - up to 7 million, which means more hemoglobin. If a person lives for a long time in conditions of lack of oxygen (for example, high in the mountains), then the number of red blood cells in his blood increases even more. As the body ages, the number of red blood cells changes in waves, but in general, children have slightly more of them than adults. A decrease in the number of red blood cells and hemoglobin in the blood below normal indicates a serious illness - anemia (anemia). One of the causes of anemia may be a lack of iron in food. Foods such as beef liver, apples and some others are rich in iron. In cases of prolonged anemia, it is necessary to take medications containing iron salts.

Along with determining the level of hemoglobin in the blood, the most common clinical blood tests include measuring the erythrocyte sedimentation rate (ESR), or erythrocyte sedimentation reaction (ERS), - these are two equal names for the same test. If you prevent blood clotting and leave it in a test tube or capillary for several hours, then without mechanical shaking, heavy red blood cells will begin to precipitate. The speed of this process in adults ranges from 1 to 15 mm/h. If this indicator is significantly higher than normal, this indicates the presence of a disease, most often inflammatory. In newborns, ESR is 1-2 mm/h. By the age of 3, ESR begins to fluctuate - from 2 to 17 mm/h. In the period from 7 to 12 years, ESR usually does not exceed 12 mm/h.

Leukocytes- white blood cells. They do not contain hemoglobin, so they are not red in color. The main function of leukocytes is to protect the body from pathogenic microorganisms and toxic substances that have penetrated inside it. Leukocytes are able to move using pseudopodia, like amoebas. This way they can leave the blood capillaries and lymphatic vessels, in which there are also a lot of them, and move towards the accumulation of pathogenic microbes. There they devour microbes, carrying out the so-called phagocytosis.

There are many types of white blood cells, but the most typical are lymphocytes, monocytes and neutrophils. Neutrophils, which, like erythrocytes, are formed in the red bone marrow, are most active in the processes of phagocytosis. Each neutrophil can absorb 20-30 microbes. If a large foreign body (for example, a splinter) invades the body, then many neutrophils stick around it, forming a kind of barrier. Monocytes - cells formed in the spleen and liver, also participate in the processes of phagocytosis. Lymphocytes, which are formed mainly in the lymph nodes, are not capable of phagocytosis, but are actively involved in other immune reactions.

1 ml of blood normally contains from 4 to 9 million leukocytes. The ratio between the number of lymphocytes, monocytes and neutrophils is called the blood formula. If a person gets sick, the total number of leukocytes increases sharply, and the blood formula also changes. By its change, doctors can determine what type of microbe the body is fighting.

In a newborn child, the number of white blood cells is significantly (2-5 times) higher than in an adult, but after a few days it decreases to a level of 10-12 million per 1 ml. Starting from the 2nd year of life, this value continues to decrease and reaches typical adult values ​​after puberty. In children, the processes of formation of new blood cells are very active, therefore among the blood leukocytes in children there are significantly more young cells than in adults. Young cells differ in their structure and functional activity from mature ones. After 15-16 years, the blood formula acquires the parameters characteristic of adults.

Platelets- the smallest formed elements of blood, the number of which reaches 200-400 million in 1 ml. Muscular work and other types of stress can increase the number of platelets in the blood several times (this, in particular, is the danger of stress for older people: after all, blood clotting depends on platelets, including the formation of blood clots and blockage of small vessels in the brain and heart muscles). The place of platelet formation is the red bone marrow and spleen. Their main function is to ensure blood clotting. Without this function, the body becomes vulnerable at the slightest injury, and the danger lies not only in the fact that a significant amount of blood is lost, but also in the fact that any open wound is a gateway to infection.

If a person is injured, even shallowly, the capillaries are damaged, and platelets along with the blood end up on the surface. Here they are affected by two important factors - low temperature (much lower than 37 ° C inside the body) and an abundance of oxygen. Both of these factors lead to the destruction of platelets, and from them substances are released into the plasma that are necessary for the formation of a blood clot - a thrombus. In order for a blood clot to form, the blood must be stopped by squeezing a large vessel if blood is pouring heavily from it, since even the process of thrombus formation that has begun will not go to completion if new and new portions of blood with a high temperature are constantly entering the wound and not yet destroyed platelets.

To prevent blood from clotting inside the vessels, it contains special anti-clotting substances - heparin, etc. As long as the vessels are not damaged, there is a balance between substances that stimulate and inhibit coagulation. Damage to blood vessels leads to disruption of this balance. In old age and with increasing disease, this balance in a person is also disturbed, which increases the risk of blood clotting in small vessels and the formation of a life-threatening blood clot.

Age-related changes in platelet function and blood coagulation were studied in detail by A. A. Markosyan, one of the founders of age-related physiology in Russia. It was found that in children, coagulation occurs more slowly than in adults, and the resulting clot has a looser structure. These studies led to the formation of the concept of biological reliability and its increase in ontogenesis.