Internal environment of the body: composition, properties and functions. Components of the internal environment of the human body

Help with a question: Internal environment body and ITS IMPORTANCE! and got the best answer

Answer from Anastasia Syurkaeva[guru]
The internal environment of the body and its significance
The phrase “internal environment of the body” appeared thanks to the French physiologist Claude Bernard, who lived in the 19th century. In his works he emphasized that a necessary condition 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 is the 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 metabolic 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 fluid) .
They all have different compositions and differ in their functional properties. Moreover, the internal environment of the human body may have a slight 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 blood vessels (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 to organs necessary substances, removing waste products from the body. It also performs protective and humoral functions.
Tissue fluid consists of water and nutrients dissolved in it, CO2, O2, as well as dissimilation products. It is located in the spaces between tissue cells and is formed by blood plasma. Tissue fluid is intermediate between blood and cells. It transports O2, mineral salts, and nutrients from the blood to the cells.
Lymph consists of water and organic substances 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.

text_fields

text_fields

arrow_upward

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, the constancy life processes cells require appropriate constancy of their environment, i.e. internal environment.

Homeostasis (homeostasis)

text_fields

text_fields

arrow_upward

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. Such 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 environment on the other hand, it is ensured by a property of the body 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 of 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 functional 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 them 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, the lymph flowing from the tissues enters the blood through the thoracic lymphatic duct, ensuring the maintenance of a constant 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

text_fields

text_fields

arrow_upward

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 sensitive devices 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

text_fields

text_fields

arrow_upward

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 the internal environment in order to bring it into line 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 more or less people living in a certain region and belonging to the same social and age group, but the constants of the internal environment are different healthy people may vary. Thus, homeostatic regulation of the constancy of the internal environment does not mean complete identity of its composition in different persons. 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. are 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 activities 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.

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 inside, an important role belongs to the internal environment of the body - it includes bodies separated from the world without points of contact with 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, transmits essential vitamins for life, protects 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 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.

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 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 actions between cells are regulated. 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 roundworms, arthropods, mollusks, insects, a special internal structure has formed. 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 intercellular substances members of the VSO 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. The transfer of hormones and active substances is carried out from the place where they were born to the target points, once on it the substance will go to 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%
• shaped 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. The same property of the human body is determined by its 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 a strong immune system this will not happen, resistance will destroy enemies.

The ability to protect against infectious diseases is 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.

It surrounds all cells of the body, through which metabolic reactions occur in organs and tissues. Blood (except 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 thin, blindly closed capillaries lymphatic system and from that moment it turns into lymph.

Since the internal environment of the body maintains the constancy of physical and chemical properties, which persists 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 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 from the place of its formation with blood plasma water ( 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 physiological 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 at high physical activity, in case of 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 more low content NaCl, 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 is added to hemoglobin, an unstable compound is formed in the capillaries of the lungs - 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 red bone marrow spongy substance of bones.

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, with 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. 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: 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, erythrocytes 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 process of blood coagulation 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 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 appears 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.

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 the 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, main task which is to maintain a constant level of nutrient concentrations near 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 humoral mechanisms, ensuring 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 cell wall and the cytoplasmic membrane. Then further development animals followed the principle of multicellularity. In coelenterate organisms there was a cavity separating cells and 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 animals of the classes of 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. Its 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 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 cells, with which the intercellular fluid, also included in the VSO, is in contact.

Blood

The internal environment of the body is partly formed by blood. This 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 is erythrocytes, platelets, and leukocytes. The former are engaged in transporting oxygen and carbon dioxide, although they are also capable of playing 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 precisely by blood, which plays the role of a barrier between areas of the body in contact with the external environment and cells, then immune function blood is the second most important 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 travel to 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 media 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 concentrations 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. So far, this system is the most effective of all those presented 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 is collected in 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 joint capsule, the only way The nutrition of articular cartilage is precisely the synovium. 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. And probably the most important function 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 them from them harmful products. In this way homeostasis is maintained, main characteristic life activity. This also means that it is virtually impossible to separate the external environment of otragism from the internal one.