Internal environment of the human body. Internal environment of the body

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In physiology Wednesday is a set of living conditions for living beings. Highlight external and internal environment.

External environment

External environment of the body called a complex of factors located outside the body, but necessary for its life.

Internal environment

Internal environment of the body called a collection of biological fluids (blood, lymph, tissue fluid) that wash cells and tissue structures and take part in metabolic processes.

The concept of “internal environment” was proposed in the 19th century by Claude Bernard, thereby emphasizing that, unlike the changeable external environment in which a living organism exists, constancy life processes cells require appropriate constancy of their environment, i.e. internal environment.

Homeostasis (homeostasis)

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The external environment has not only beneficial but also harmful influences on the life of the body. However, healthy body functions normally if environmental influences do not exceed acceptable limits. This dependence of the life activity of the organism on the external environment, on the one hand, and the relative stability and independence of life processes from changes in the environment, on the other hand, is ensured by the property of the organism, called homeostasis (homeostasis).

Homeostasis (homeostasis) - property of an organism that ensures relative stability and independence of life processes from changes in the environment, if environmental influences do not exceed the limits of admissibility.

The body is an ultrastable system that itself searches for the most stable and optimal state, keeping various parameters of functions within the boundaries of physiological (“normal”) fluctuations.

Homeostasis- relative dynamic constancy of the internal environment and stability physiological functions. This is precisely dynamic, and not static, constancy, since it implies not only the possibility, but the necessity of fluctuations in the composition of the internal environment and function parameters within physiological boundaries in order to achieve the optimal level of vital activity of the organism.

The activity of cells requires an adequate function of supplying them with oxygen and effectively flushing out carbon dioxide and other waste substances or metabolites. To restore decaying protein structures and extract energy, cells must receive plastic and energy material that enters the body with food. Cells receive all this from their surrounding microenvironment through tissue fluid. The constancy of the latter is maintained due to the exchange of gases, ions and molecules with the blood.

Consequently, the constancy of the blood composition and the state of the barriers between blood and tissue fluid, the so-called histohematic barriers, are the conditions for homeostasis of the cell microenvironment.

The selective permeability of these barriers provides a certain specificity in the composition of the cell microenvironment necessary for their functions.

On the other hand, tissue fluid participates in the formation of lymph and exchanges with lymphatic capillaries draining tissue spaces, which makes it possible to effectively remove large molecules from the cellular microenvironment that are unable to diffuse through histohematic barriers into the blood. In turn, lymph flowing from the tissues through the chest lymphatic duct enters the blood, ensuring the maintenance of the constancy of its composition. Consequently, in the body there is a continuous exchange between fluids of the internal environment, which is a prerequisite for homeostasis.

Interaction of internal and external environment

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The interrelations of the components of the internal environment with each other, with the external environment and the role of the main physiological systems in the implementation of the interaction of the internal and external environment are presented in Fig. 2.1.

Rice. 2.1. Scheme of interrelations of the internal environment of the body.

The external environment influences the body through the perception of its characteristics by the sensitive apparatus of the nervous system (receptors, sensory organs), through the lungs, where gas exchange takes place, and through gastrointestinal tract where water and food ingredients are absorbed. The nervous system exerts its regulatory effect on cells due to the release of special intermediaries at the ends of nerve conductors - meh diators, arriving through the microenvironment of cells to special structural formations cell membranes - receptors.

The influence of the external environment perceived by the nervous system can be mediated through endocrine system, secreting special humoral regulators into the blood - hormones . In turn, the substances contained in the blood and tissue fluid, to a greater or lesser extent, irritate the receptors of the interstitial space and the bloodstream, thereby providing the nervous system with information about the composition of the internal environment. Removal of metabolites and foreign substances from the internal environment is carried out through the excretory organs, mainly the kidneys, as well as the lungs and digestive tract.

Constancy of the internal environment

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Constancy of the internal environment - the most important condition vital activity of the body. Therefore, deviations in the composition of fluids in the internal environment are perceived by numerous receptor structures and cellular elements, with the subsequent activation of biochemical, biophysical and physiological regulatory reactions aimed at eliminating the deviation. At the same time, the regulatory reactions themselves cause changes in internal environment in order to bring it into conformity with the new conditions of existence of the organism. Therefore, regulation of the internal environment always aims to optimize its composition and physiological processes in the body.

The boundaries of homeostatic regulation of the constancy of the internal environment can be rigid for some parameters and flexible for others.

Respectively, The parameters of the internal environment are called:
A)hard constants, if the range of their deviations is very small (pH, ion concentration in the blood),

b) or plastic constants, i.e. subject to relatively large fluctuations (level of glucose, lipids, residual nitrogen, interstitial fluid pressure, etc.).

Constants vary depending on age, social and professional conditions, time of year and day, geographical and natural conditions, and also have gender and individual characteristics. Environmental conditions are often the same for a larger or smaller number of people living in a certain region and belonging to the same social and age group, but the constants of the internal environment may differ among different healthy people. Thus, homeostatic regulation of the constancy of the internal environment does not mean complete identity of its composition in different individuals. However, despite individual and group characteristics, homeostasis ensures the maintenance of normal parameters of the internal environment of the body.

Usually the norm call the average statistical values ​​of the parameters and characteristics of the vital functions of healthy individuals, as well as the intervals within which fluctuations in these values ​​correspond to homeostasis, i.e. able to keep the body at the level of optimal functioning.

Accordingly, for general characteristics The internal environment of the body normally gives intervals of fluctuations in its various indicators, for example, the quantitative content of various substances in the blood of healthy people. At the same time, the characteristics of the internal environment are interrelated and interdependent quantities. Therefore, shifts in one of them are often compensated by others, which does not necessarily affect the level of optimal functioning and human health.

The internal environment is a reflection of the most complex integration of life activity different cells, tissues, organs and systems with environmental influences.

This makes it particularly important individual characteristics internal environment that distinguishes each person. The basis of the individuality of the internal environment is genetic individuality , as well as prolonged exposure to certain environmental conditions. Respectively, physiological norm- this is an individual optimum of life activity, i.e. the most coordinated and effective combination of all life processes in real environmental conditions.

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 the constancy of physical and chemical properties, persisting 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 following functions:

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

2) nutritional - transfers nutrients absorbed in the intestines to all organs and tissues. In this way they are supplied with 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 the acid-base balance in tissues. In addition, it transports hormones and other physiologically active substances from the places 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. This also prevents it from entering the bloodstream. pathogens(bacteria, viruses, fungi). 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.

Plasma is the liquid medium of blood containing 90-92% water and 8-10% various substances. plasmas (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, then water will be sucked out of the red blood cells and they will shrink. In these cases, the so-called saline, which in terms of salt concentration, 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, leukocytes 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 with the smallest volume and allows them to pass through the smallest blood capillaries, quickly delivering oxygen to the 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 it from the tissues significant amount carbon dioxide. 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 react 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. IN early XIX century, the first attempts were made to transfuse blood directly from one person to another, but a very large number of complications were observed: red blood cells after blood transfusion 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. That's why 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 most often occurs 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 blood coagulation process is very complex, includes many stages, and is catalyzed by many. 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 The lymph nodes, performing 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.

"Biology. Human. 8th grade". D.V. Kolesova and others.

Components of the internal environment of the body. functions of blood, tissue fluid and lymph

Question 1. Why do cells need a liquid environment for vital processes?
Cells need nutrition and energy to function normally. The cell receives nutrients in dissolved form, i.e. from a liquid medium.

Question 2. What components does the internal environment of the body consist of? How are they related?
The internal environment of the body is blood, lymph and tissue fluid that washes the cells of the body. In tissues, the liquid component of blood (plasma) partially seeps through the thin walls of the capillaries, passes into the intercellular spaces and becomes tissue fluid. Excess tissue fluid is collected in the lymphatic vascular system and is called lymph. Lymph, in turn, having traveled a rather complex path through the lymphatic vessels, enters the blood. Thus, the circle closes: blood - tissue fluid - lymph - blood again.

Question 3. What functions do blood, tissue fluid and lymph perform?
Blood performs the following functions in the human body:
Transport: blood carries oxygen, nutrients; removes carbon dioxide and metabolic products; distributes heat.
Protective: leukocytes, antibodies, macrophages protect against foreign bodies and substances.
Regulatory: hormones (substances that regulate vital processes) are distributed through the blood.
Participation in thermoregulation: blood transfers heat from organs where it is produced (for example, from muscles) to organs that give off heat (for example, to the skin).
Mechanical: gives elasticity to organs due to the flow of blood to them.
Tissue (or interstitial) fluid is the link between blood and lymph. It is present in the intercellular spaces of all tissues and organs. From this fluid, cells absorb the substances they need and secrete metabolic products into it. Its composition is similar to that of blood plasma, but differs from plasma in that it contains less protein. The composition of tissue fluid varies depending on the permeability of blood and lymphatic capillaries, on the characteristics of metabolism, cells and tissues. If lymph circulation is impaired, tissue fluid can accumulate in the intercellular spaces; this leads to the formation of edema. Lymph performs a transport and protective function, since lymph flowing from tissues passes on the way to the veins through biological filters - lymph nodes. Here, foreign particles are retained and, therefore, do not enter the bloodstream and microorganisms that have entered the body are destroyed. In addition, the lymphatic vessels are like a drainage system that removes excess tissue fluid found in the organs.

Question 4. Explain what lymph nodes are and what happens in them. Show yourself where some of them are.
Lymph nodes are formed by hematopoietic connective tissue and are located along the large lymphatic vessels. An important function of the lymphatic system is due to the fact that lymph flowing from tissues passes through the lymph nodes. Some foreign particles, such as bacteria and even dust particles, are retained in these nodes. Lymphocytes are formed in the lymph nodes, which are involved in creating immunity. In the human body, cervical, axillary, mesenteric and inguinal lymph nodes can be found.

Question 5. What is the relationship between the structure of an erythrocyte and its function?
Red blood cells are red blood cells; in mammals and humans they do not contain a nucleus. They have a biconcave shape; their diameter is approximately 7-8 microns. The total surface of all red blood cells is approximately 1500 times larger than the surface of the human body. The transport function of red blood cells is due to the fact that they contain the protein hemoglobin, which contains divalent iron. The absence of a nucleus and the biconcave shape of the erythrocyte contribute to the efficient transfer of gases, since the absence of a nucleus allows the entire volume of the cell to be used for transporting oxygen and carbon dioxide, and the cell surface, increased due to the biconcave shape, absorbs oxygen faster.

IN survey 6. What are the functions of leukocytes?
Leukocytes are divided into granular (granulocytes) and non-granular (agranulocytes). The granular ones include neutrophils (50-79% of all leukocytes), eosinophils and basophils. Non-granular cells include lymphocytes (20-40% of all leukocytes) and monocytes. Neutrophils, monocytes and eosinophils have greatest ability to phagocytosis - devouring foreign bodies (microorganisms, foreign compounds, dead particles of body cells, etc.), provide cellular immunity. Lymphocytes provide humoral immunity. Lymphocytes can live for a very long time; they have “immune memory,” that is, an enhanced reaction when they encounter a foreign body again. T lymphocytes are thymus-dependent leukocytes. These are killer cells - they kill foreign cells. There are also helper T lymphocytes: they stimulate the immune system by interacting with B lymphocytes. B lymphocytes are involved in the formation of antibodies.
Thus, the main functions of leukocytes are phagocytosis and the creation of immunity. In addition, leukocytes play the role of orderlies, as they destroy dead cells. The number of leukocytes increases after eating, during heavy muscular work, during inflammatory processes, infectious diseases. A decrease in the number of white blood cells below normal (leukopenia) may be a sign of a serious illness.

1. The internal environment of the body, its composition and significance. §14.

The structure and significance of the cell. §1.

Answers:

1. Characterize the internal environment of the human body and the significance of its relative constancy.

Most cells in the body are not connected to the external environment. Their vital activity is ensured by the internal environment, which consists of three types of fluids: intercellular (tissue) fluid, with which the cells are in direct contact, blood and lymph.

It maintains the relative constancy of its composition - physical and chemical properties (homeostasis), which ensures the stability of all body functions.

Maintaining homeostasis is the result of neurohumoral self-regulation.

Each cell needs a constant supply of oxygen and nutrients and the removal of metabolic products. Both occur through the blood. The cells of the body do not come into direct contact with the blood, since the blood moves through the vessels in a closed circuit. circulatory system. Each cell is washed by a liquid that contains the substances it needs. This is intercellular or tissue fluid.

Between the tissue fluid and the liquid part of the blood - plasma, exchange of substances occurs through the walls of the capillaries by diffusion.

Lymph is formed from tissue fluid entering the lymphatic capillaries, which originate between tissue cells and pass into lymphatic vessels that flow into the large veins of the chest. Blood is liquid connective tissue. It consists of a liquid part - plasma and separate

shaped elements: red blood cells - erythrocytes, white blood cells - leukocytes and blood platelets - platelets. Formed elements of blood are formed in hematopoietic organs: in red bone marrow, liver, spleen, lymph nodes.

1 mm cu. blood contains 4.5-5 million red blood cells, 5-8 thousand leukocytes, 200-400 thousand platelets. The human body contains 4.5-6 liters of blood (1/13 of its body weight).

Plasma makes up 55% of blood volume, and formed elements - 45%.

The red color of blood is given by red blood cells containing red respiratory pigment - hemoglobin, which absorbs oxygen in the lungs and releases it to the tissues. Plasma is a colorless transparent liquid consisting of inorganic and organic substances (90% water, 0.9% various mineral salts).

Organic substances in plasma include proteins - 7%, fats - 0.7%, 0.1% - glucose, hormones, amino acids, metabolic products. Homeostasis is maintained by the activities of the respiratory, excretory, digestive organs, etc., by the influence of the nervous system and hormones. In response to influences from the external environment, responses automatically arise in the body that prevent strong changes in the internal environment.

The vital activity of body cells depends on the salt composition of the blood. And the constancy of the salt composition of plasma ensures normal structure and blood cell function. Blood plasma performs the following functions:

1) transport; 2) excretory; 3) protective; 4) humoral.

Most cells in the body are not connected to the external environment.

Their vital activity is ensured by the internal environment, which consists of three types of fluids: intercellular (tissue) fluid, with which the cells are in direct contact, blood and lymph.

the internal environment provides cells with the substances necessary for their vital functions, and through this, decay products are removed. The internal environment of the body has a relative constancy of composition and physical and chemical properties. Only under this condition will the cells function normally.

Blood- this is a tissue with a liquid basic substance (plasma) in which there are cells - formed elements: erythrocytes, leukocytes, platelets.

Tissue fluid - formed from blood plasma penetrating into the intercellular space

Lymph- a translucent yellowish liquid is formed from tissue fluid trapped in the lymphatic capillaries.

2. CELL: ITS STRUCTURE, COMPOSITION,

LIFE PROPERTIES.

The human body has a cellular structure.

The cells are located in the intercellular substance, which provides them with mechanical strength, nutrition and respiration. Cells vary in size, shape, and function.

Cytology (Greek “cytos” - cell) studies the structure and functions of cells. The cell is covered with a membrane consisting of several layers of molecules, providing selective permeability of substances. The space between the membranes of neighboring cells is filled with liquid intercellular substance. Main function membranes: exchange of substances takes place between the cell and the intercellular substance.

Cytoplasm- viscous semi-liquid substance.

The cytoplasm contains a number of the smallest cell structures - organelles, which perform various functions: endoplasmic reticulum, ribosomes, mitochondria, lysosomes, Golgi complex, cell center, nucleus.

Endoplasmic reticulum- a system of tubules and cavities that penetrates the entire cytoplasm.

The main function is participation in the synthesis, accumulation and movement of the main organic substances produced by the cell, protein synthesis.

Ribosomes- dense bodies containing protein and ribonucleic acid (RNA). They are the site of protein synthesis. The Golgi complex is a membrane-bounded cavity with tubes extending from them and vesicles located at their ends.

The main function is the accumulation of organic substances and the formation of lysosomes. The cell center is formed by two bodies that participate in cell division. These bodies are located near the nucleus.

Core- the most important structure of the cell.

The cavity of the nucleus is filled with nuclear juice. It contains the nucleolus, nucleic acids, proteins, fats, carbohydrates, chromosomes. Chromosomes contain hereditary information.

Cells are characterized by a constant number of chromosomes. The cells of the human body contain 46 chromosomes, and the germ cells contain 23.

Lysosomes- round bodies with a complex of enzymes inside. Their main function is to digest food particles and remove dead organelles. Cells contain inorganic and organic compounds.

Inorganic substances - water and salts.

Water makes up up to 80% of the cell's mass. It dissolves substances involved in chemical reactions: it transports nutrients, removes waste and harmful compounds from the cell.

Mineral salts- sodium chloride, potassium chloride, etc. - play an important role in the distribution of water between cells and the intercellular substance.

Individual chemical elements: oxygen, hydrogen, nitrogen, sulfur, iron, magnesium, zinc, iodine, phosphorus are involved in the creation of vital organic compounds.

Organic compounds form up to 20-30% of the mass of each cell.

Among them, proteins, fats, carbohydrates and nucleic acids are of greatest importance.

Squirrels- the main and most complex organic substances found in nature.

The protein molecule is large and consists of amino acids. Proteins serve as the building blocks of cells. They participate in the formation of cell membranes, nucleus, cytoplasm, and organelles.

Enzyme proteins are flow accelerators chemical reactions. There are up to 1000 different proteins in just one cell. Consist of carbon, hydrogen, nitrogen, oxygen, sulfur, phosphorus. Carbohydrates - consist of carbon, hydrogen, oxygen.

Carbohydrates include glucose, animal starch and glycogen. The decay of 1 g releases 17.2 kJ of energy.

Fats formed by the same chemical elements the same as carbohydrates.

Fats are insoluble in water. They are part of cell membranes and serve as a reserve source of energy in the body. When 1 g of fat is broken down, 39.1 kJ is released

Nucleic acids There are two types - DNA and RNA. DNA is located in the nucleus, is part of chromosomes, determines the composition of cell proteins and the transmission of hereditary characteristics and properties from parents to offspring. The functions of RNA are associated with the formation of proteins characteristic of this cell.

The main vital property of a cell is metabolism. Nutrients and oxygen are constantly supplied to the cells from the intercellular substance and decay products are released.

Substances that enter the cell participate in biosynthesis processes.

Biosynthesis is the formation of proteins, fats, carbohydrates and their compounds from simpler substances.

Simultaneously with biosynthesis, organic compounds decompose in cells. Most decomposition reactions involve oxygen and

release of energy. As a result of metabolism, the composition of cells is constantly updated: some substances are formed, while others are destroyed.

The property of living cells, tissues, the whole organism to respond to external or internal influences - stimuli is called irritability. In response to chemical and physical irritations, specific changes in their vital activity occur in cells.

Cells are characterized growth and reproduction. Each of the resulting daughter cells grows and reaches the size of the mother cell.

The new cells perform the function of the mother cell. The lifespan of cells varies: from several hours to tens of years.

Thus, a living cell has a number of vital properties: metabolism, irritability, growth and reproduction, mobility, on the basis of which the functions of the whole organism are carried out.

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Components of the internal environment

Any organism - unicellular or multicellular - needs certain conditions of existence. These conditions are provided to organisms by the environment to which they have adapted during evolutionary development.

The first living formations arose in the waters of the World Ocean, and sea water served as their habitat.

As living organisms became more complex, some of their cells became isolated from the external environment. So part of the habitat ended up inside the organism, which allowed many organisms to leave aquatic environment and start living on land. The content of salts in the internal environment of the body and in sea ​​water approximately the same.

The internal environment for human cells and organs is blood, lymph and tissue fluid.

Relative constancy of the internal environment

In the internal environment of the body, in addition to salts, there are a lot of different substances - proteins, sugar, fat-like substances, hormones, etc.

Each organ constantly releases the products of its vital activity into the internal environment and receives from it the substances it needs. And, despite such active exchange, the composition of the internal environment remains practically unchanged.

The fluid leaving the blood becomes part of the tissue fluid. Most of this fluid returns to the capillaries before they connect with the veins that return blood to the heart, but about 10% of the fluid does not enter the vessels.

The walls of capillaries consist of a single layer of cells, but there are narrow gaps between adjacent cells. The contraction of the heart muscle creates blood pressure, causing water with dissolved salts and nutrients to pass through these gaps.

All body fluids are connected to each other. The extracellular fluid comes into contact with the blood and the cerebrospinal fluid that bathes the spinal cord and brain.

This means that the regulation of the composition of body fluids occurs centrally.

Tissue fluid washes cells and serves as a habitat for them.

It is constantly renewed through the system of lymphatic vessels: this fluid is collected in vessels, and then through the largest lymphatic vessel it enters the general bloodstream, where it mixes with the blood.

Blood composition

The well-known red liquid is actually tissue.

For a long time, blood was recognized as a powerful force: sacred oaths were sealed with blood; the priests made their wooden idols “cry blood”; The ancient Greeks sacrificed blood to their gods.

Some philosophers Ancient Greece They considered blood to be the carrier of the soul. The ancient Greek physician Hippocrates prescribed the blood of healthy people to the mentally ill. He thought that in the blood of healthy people there is a healthy soul. Indeed, blood is the most amazing tissue of our body.

Blood mobility is the most important condition for the life of the body.

About half of the blood volume is its liquid part - plasma with salts and proteins dissolved in it; the other half consists of various formed elements of blood.

Blood cells are divided into three main groups: white blood cells (leukocytes), red blood cells (erythrocytes) and platelets, or platelets.

All of them are formed in bone marrow (soft fabric filling the cavity tubular bones), but some leukocytes are able to multiply already when leaving the bone marrow.

There are many various types leukocytes - most are involved in protecting the body from diseases.

Blood plasma

In 100 ml of blood plasma healthy person contains about 93 g of water.

The rest of the plasma consists of organic and inorganic substances. Plasma contains minerals, proteins, carbohydrates, fats, metabolic products, hormones, vitamins.

Plasma minerals are represented by salts: chlorides, phosphates, carbonates and sulfates of sodium, potassium, calcium and magnesium. They can be in the form of ions or in a non-ionized state.

Even minor violation the salt composition of plasma can be detrimental to many tissues, and above all to the cells of the blood itself.

The total concentration of mineral soda, proteins, glucose, urea and other substances dissolved in plasma creates osmotic pressure. Due to osmotic pressure, liquid penetrates through cell membranes, which ensures the exchange of water between blood and tissue. The constancy of the osmotic pressure of the blood is important for the life of the body's cells.

The membranes of many cells, including blood cells, are also semi-permeable.

Red blood cells

Red blood cells are the most numerous blood cells; their main function is to transport oxygen. Conditions that increase the body's need for oxygen, such as living at high altitudes or constant physical activity, stimulate the production of red blood cells. Red blood cells live in the bloodstream for about four months, after which they are destroyed.

Leukocytes

Leukocytes, or white blood cells of variable shape.

They have a nucleus embedded in a colorless cytoplasm. The main function of leukocytes is protective. Leukocytes are not only carried by the bloodstream, but are also capable of independent movement using pseudopods (pseudopods). Penetrating through the walls of capillaries, leukocytes move towards the accumulation of pathogenic microbes in the tissue and, with the help of pseudopods, capture and digest them.

This phenomenon was discovered by I.I. Mechnikov.

Platelets, or blood platelets

Platelets, or blood platelets, are very fragile and are easily destroyed when blood vessels are damaged or when blood comes into contact with air.

Platelets play an important role in blood clotting.

Damaged tissue releases histomine, a substance that increases blood flow to the damaged area and promotes the release of fluid and proteins of the blood coagulation system from the bloodstream into the tissue.

As a result of a complex sequence of reactions, blood clots quickly form, stopping the bleeding. Blood clots prevent bacteria and other foreign factors from entering the wound.

The mechanism of blood clotting is very complex. Plasma contains a soluble protein, fibrinogen, which, during blood clotting, turns into insoluble fibrin and precipitates in the form of long threads.

From the network of these threads and the blood cells that linger in the network, a blood clot is formed.

This process occurs only in the presence of calcium salts. Therefore, if calcium is removed from the blood, the blood loses its ability to clot. This property is used in canning and blood transfusions.

In addition to calcium, other factors also take part in the coagulation process, such as vitamin K, without which the formation of prothrombin is disrupted.

Blood functions

Blood performs various functions in the body: it delivers oxygen and nutrients to cells; carries away carbon dioxide and metabolic end products; participates in the regulation of activities various organs and systems through the transfer of biologically active substances-hormones and etc.; helps maintain the constancy of the internal environment - chemical and gas composition, body temperature; protects the body from foreign bodies and harmful substances, destroying and neutralizing them.

The body's protective barriers

The body's protection from infections is ensured not only by the phagocytic function of leukocytes, but also by the formation of special protective substances - antibodies and antitoxins.

They are produced by leukocytes and tissues of various organs in response to the introduction of pathogens into the body.

Antibodies are protein substances that can glue microorganisms together, dissolve or destroy them. Antitoxins neutralize poisons secreted by microbes.

Protective substances are specific and act only on those microorganisms and their poisons under the influence of which they were formed.

Antibodies can remain in the blood for a long time. Thanks to this, a person becomes immune to certain infectious diseases.

Immunity to diseases due to the presence of special protective substances in the blood and tissues is called immunity.

The immune system

Immunity, according to modern views, is the body’s immunity to various factors (cells, substances) that carry genetically foreign information.

If any cells or complex organic substances appear in the body that differ from the cells and substances of the body, then thanks to immunity they are eliminated and destroyed.

The main task of the immune system is to maintain the genetic constancy of the organism during ontogenesis. When cells divide due to mutations in the body, cells with an altered genome are often formed. To prevent these mutant cells from causing disturbances in the development of organs and tissues during further division, they are destroyed by the body’s immune systems.

In the body, immunity is ensured due to the phagocytic properties of leukocytes and the ability of some body cells to produce protective substances - antibodies.

Therefore, by its nature, immunity can be cellular (phagocytic) and humoral (antibodies).

Immunity to infectious diseases is divided into natural, developed by the body itself without artificial interventions, and artificial, resulting from the introduction of special substances into the body.

Natural immunity manifests itself in a person from birth (congenital) or occurs after illness (acquired). Artificial immunity may be active or passive. Active immunity is developed when weakened or killed pathogens or their weakened toxins are introduced into the body.

This immunity does not occur immediately, but persists long time- for several years and even for the rest of your life. Passive immunity occurs when a therapeutic serum with ready-made protective properties is introduced into the body. This immunity is short-lived, but appears immediately after administration of the serum.

Blood clotting also refers to the body's protective reactions. It protects the body from blood loss.

The reaction consists of the formation of a blood clot - a thrombus that clogs the wound site and stops bleeding.

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

Blood consists of cells (erythrocytes, leukocytes, platelets) and intercellular substance (plasma).

Blood flows through blood vessels.

Part of the plasma leaves the blood capillaries out into the tissues and turns into tissue fluid.

Tissue fluid is in direct contact with the cells of the body and exchanges substances with them. To return this fluid back into the blood, there is a lymphatic system.

Lymphatic vessels openly end in tissues; the tissue fluid that gets there is called lymph. Lymph flows through the lymphatic vessels, is cleared in the lymph nodes and returns to the veins great circle blood circulation

The internal environment of the body is characterized by homeostasis, i.e.

relative constancy of composition and other parameters. This ensures the existence of body cells in constant conditions, independent of the environment. The maintenance of homeostasis is controlled by the hypothalamus (part of the hypothalamic-pituitary system).

Internal environment of the body.

Internal environment of the body liquid. The first living organisms arose in the waters of the world's oceans, and their habitat was sea water. With the advent multicellular organisms most of the cells have lost direct contact with the external environment.

They exist surrounded by an internal environment. It consists of intercellular (tissue) fluid, blood and lymph. There is a close relationship between the three components of the internal environment. Thus, tissue fluid is formed due to the transition (filtration) of the liquid part of the blood (plasma) from the capillaries into the tissues. In its composition, it differs from plasma in the almost complete absence of proteins. A significant part of the tissue fluid returns to the blood. Some of it collects between tissue cells.

Lymphatic vessels originate in the intercellular space. They penetrate almost all organs. Lymphatic vessels facilitate the drainage of fluid from tissues.

Lymph– translucent yellowish liquid, contains lymphocytes, does not have red blood cells and platelets. In its composition, lymph differs from tissue fluid in its high protein content.

The body produces 2–4 liters of lymph per day. The lymphatic system consists of veins and lymphatic vessels running along it. Small lymphatic vessels connect into large ones and flow into large veins near the heart: lymph connects with blood. Lymph flows very slowly, at a speed of 0.3 mm/s, 1700 times slower than blood in the aorta. Along the vessels there are lymph nodes, in which the lymph is cleared of foreign substances by lymphocytes.

Internal environment performs the following functions:

Provides cells with necessary substances;
Removes metabolic products;
Supports homeostasis– constancy of the internal environment.
Thanks to the presence of lymph and blood circulation systems, as well as the action of organs and systems that ensure the flow of various substances from the external environment into the body (respiratory and digestive organs) and organs that excrete metabolic products into the external environment, mammals have the opportunity to maintain homeostasis - constancy of composition internal environment, without which the normal functioning of the body is impossible.

At the core homeostasis dynamic processes lie, since the constancy of the internal environment is constantly disrupted and just as continuously restored.

In response to influences from the external environment, responses automatically arise in the body that prevent strong changes in its internal environment.

For example, during extreme heat and overheating of the body, the temperature rises and reactions accelerate, which causes profuse sweating, that is, the release of water, the evaporation of which leads to cooling.

The most important role in ensuring homeostasis belongs to nervous system, its higher departments, as well as the endocrine glands.

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 all cellular system, transfers necessary vitamins for life, protects against adverse 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 cycle of vital products, which are secreted inside in the required quantity and receive in return the right composition substances, while creating constancy of the constituent elements, maintaining homeostasis.

The work occurs according to a strict scheme: if a liquid composition is released from blood cells, it enters the 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.

A constant circulation of fluids with various functions has been created, 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 of a complex animal mechanism, their uninterrupted operation and life are ensured by 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 a vehicle for providing 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 the flatworms and coelenterates.

Development of a separate system

A special internal structure has formed in the community of roundworms, arthropods, mollusks, and insects. 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 in 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 the 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 provides 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 man is busy running physical activity, 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 manufacturing processes depend on plasma. 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 to 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 invaders is important genetic information depending on various factors, 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.

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 through blood vessels without directly contacting 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 from tissue fluid necessary substances and oxygen, releasing carbon dioxide and waste products into it.

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 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 Vehicle. 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 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 complex structure and performs the whole complex various 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	Blood cells white with kernels	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.