The body as an open self-regulating system.

A living organism is an open system that has a connection with the environment through the nervous, digestive, respiratory, excretory systems, etc.

In the process of metabolism with food, water, during gas exchange, various chemical compounds enter the body, which undergo changes in the body, enter the structure of the body, but do not remain permanently. Assimilated substances decompose, release energy, decay products are removed into the external environment. The destroyed molecule is replaced by a new one, and so on.

The body is an open, dynamic system. In a constantly changing environment, the body maintains a stable state for a certain time.

The concept of homeostasis. General patterns of homeostasis of living systems.

homeostasis - the property of a living organism to maintain a relative dynamic constancy of the internal environment. Homeostasis is expressed in the relative constancy of the chemical composition, osmotic pressure, stability of the basic physiological functions. Homeostasis is specific and determined by the genotype.

The preservation of the integrity of the individual properties of an organism is one of the most general biological laws. This law is provided in the vertical series of generations by the mechanisms of reproduction, and throughout the life of the individual - by the mechanisms of homeostasis.

The phenomenon of homeostasis is an evolutionarily developed, hereditarily fixed adaptive property of the body to normal environmental conditions. However, these conditions can be short-term or long-term outside the normal range. In such cases, the phenomena of adaptation are characterized not only by the restoration of the usual properties of the internal environment, but also by short-term changes in function (for example, an increase in the rhythm of cardiac activity and an increase in the frequency of respiratory movements with increased muscular work). Homeostasis reactions can be directed to:

maintaining known steady state levels;

elimination or limitation of harmful factors;

development or preservation of optimal forms of interaction between the organism and the environment in the changed conditions of its existence. All these processes determine adaptation.

Therefore, the concept of homeostasis means not only a certain constancy of various physiological constants of the body, but also includes the processes of adaptation and coordination of physiological processes that ensure the unity of the body not only in the norm, but also under changing conditions of its existence.

The main components of homeostasis were defined by C. Bernard, and they can be divided into three groups:

A. Substances that provide cellular needs:

Substances necessary for the formation of energy, for growth and recovery - glucose, proteins, fats.

NaCl, Ca and other inorganic substances.

Oxygen.

internal secretion.

B. Environmental factors affecting cellular activity:

osmotic pressure.

Temperature.

Hydrogen ion concentration (pH).

B. Mechanisms that ensure structural and functional unity:

Heredity.

Regeneration.

immunobiological reactivity.

The principle of biological regulation ensures the internal state of the organism (its content), as well as the relationship between the stages of ontogenesis and phylogenesis. This principle has become widespread. When studying it, cybernetics arose - the science of purposeful and optimal control of complex processes in wildlife, in human society, industry (Berg I.A., 1962).

A living organism is a complex controlled system where many variables of the external and internal environment interact. Common to all systems is the presence input variables, which, depending on the properties and laws of the system's behavior, are transformed into weekend variables (Fig. 10).

Rice. 10 - General scheme of homeostasis of living systems

The output variables depend on the input variables and the laws of the system behavior.

The influence of the output signal on the control part of the system is called feedback , which is of great importance in self-regulation (homeostatic reaction). Distinguish negative andpositive feedback.

negative feedback reduces the influence of the input signal on the value of the output according to the principle: "the more (at the output), the less (at the input)". It helps to restore the homeostasis of the system.

At positive feedback, the value of the input signal increases according to the principle: "the more (at the output), the more (at the input)". It enhances the resulting deviation from the initial state, which leads to a violation of homeostasis.

However, all types of self-regulation operate on the same principle: self-deviation from the initial state, which serves as a stimulus for turning on correction mechanisms. So, normal blood pH is 7.32 - 7.45. A shift in pH by 0.1 leads to a violation of cardiac activity. This principle was described by Anokhin P.K. in 1935 and called the feedback principle, which serves to implement adaptive reactions.

General principle of homeostatic response(Anokhin: "Theory of functional systems"):

deviation from the initial level → signal → activation of regulatory mechanisms based on the feedback principle → correction of changes (normalization).

So, during physical work, the concentration of CO 2 in the blood increases → pH shifts to the acid side → the signal enters the respiratory center of the medulla oblongata → centrifugal nerves conduct an impulse to the intercostal muscles and breathing deepens → a decrease in CO 2 in the blood, pH is restored.

Mechanisms of regulation of homeostasis at the molecular-genetic, cellular, organismal, population-species and biospheric levels.

Regulatory homeostatic mechanisms function at the gene, cellular and systemic (organismic, population-species and biospheric) levels.

Gene mechanisms homeostasis. All phenomena of body homeostasis are genetically determined. Already at the level of primary gene products there is a direct connection - "one structural gene - one polypeptide chain". Moreover, there is a collinear correspondence between the DNA nucleotide sequence and the amino acid sequence of the polypeptide chain. The hereditary program of the individual development of the organism provides for the formation of species-specific characteristics not in constant, but in changing environmental conditions, within the limits of the hereditarily determined norm of reaction. The double helix of DNA is essential in the processes of its replication and repair. Both are directly related to ensuring the stability of the functioning of the genetic material.

From a genetic point of view, one can distinguish between elementary and systemic manifestations of homeostasis. Examples of elementary manifestations of homeostasis are: gene control of thirteen blood coagulation factors, gene control of histocompatibility of tissues and organs, which allows transplantation.

The transplanted area is called transplant. The organism from which tissue is taken for transplantation is donor , and to whom they transplant - recipient . The success of transplantation depends on the immunological reactions of the body. There are autotransplantation, syngeneic transplantation, allotransplantation and xenotransplantation.

Autotransplantation – transplantation of tissues in the same organism. In this case, the proteins (antigens) of the transplant do not differ from the proteins of the recipient. There is no immunological reaction.

Syngeneic transplant carried out in identical twins with the same genotype.

allotransplantation – transplantation of tissues from one individual to another belonging to the same species. The donor and recipient differ in antigens, therefore, in higher animals, long-term engraftment of tissues and organs is observed.

Xenotransplantation – donor and recipient belong to different types of organisms. This type of transplantation succeeds in some invertebrates, but such transplants do not take root in higher animals.

In transplantation, the phenomenon is of great importance immunological tolerance (tissue compatibility). Suppression of immunity in the case of tissue transplantation (immunosuppression) is achieved by: suppression of the activity of the immune system, radiation, administration of antilymphotic serum, hormones of the adrenal cortex, chemical preparations - antidepressants (imuran). The main task is to suppress not just immunity, but transplant immunity.

transplant immunity determined by the genetic constitution of the donor and recipient. The genes responsible for the synthesis of antigens that cause a reaction to the transplanted tissue are called tissue incompatibility genes.

In humans, the main genetic system of histocompatibility is the HLA (Human Leukocyte Antigen) system. Antigens are sufficiently well represented on the surface of leukocytes and are determined using antisera. The plan of the structure of the system in humans and animals is the same. A unified terminology has been adopted to describe the genetic loci and alleles of the HLA system. Antigens are designated: HLA-A 1 ; HLA-A 2 etc. New antigens that have not been finally identified are designated - W (Work). Antigens of the HLA system are divided into 2 groups: SD and LD (Fig. 11).

Antigens of the SD group are determined by serological methods and are determined by the genes of 3 subloci of the HLA system: HLA-A; HLA-B; HLA-C.

Rice. 11 - HLA main human histocompatibility genetic system

LD - antigens are controlled by the HLA-D sublocus of the sixth chromosome, and are determined by the method of mixed cultures of leukocytes.

Each of the genes that control HLA - human antigens, has a large number of alleles. So the HLA-A sublocus controls 19 antigens; HLA-B - 20; HLA-C - 5 "working" antigens; HLA-D - 6. Thus, about 50 antigens have already been found in humans.

The antigenic polymorphism of the HLA system is the result of the origin of one from the other and the close genetic relationship between them. The identity of the donor and recipient according to the antigens of the HLA system is necessary for transplantation. Transplantation of a kidney identical in 4 antigens of the system provides survival by 70%; 3 - 60%; 2 - 45%; 1 - 25%.

There are special centers that conduct the selection of a donor and recipient for transplantation, for example, in the Netherlands - "Eurotransplant". Typing by antigens of the HLA system is also carried out in the Republic of Belarus.

Cellular mechanisms homeostasis are aimed at restoring the cells of tissues, organs in case of violation of their integrity. The totality of processes aimed at restoring destructible biological structures is called regeneration. Such a process is characteristic of all levels: renewal of proteins, components of cell organelles, whole organelles and the cells themselves. Restoration of organ functions after an injury or rupture of a nerve, wound healing is important for medicine in terms of mastering these processes.

Tissues, according to their regenerative capacity, are divided into 3 groups:

Tissues and organs that are characterized cellular regeneration (bones, loose connective tissue, hematopoietic system, endothelium, mesothelium, mucous membranes of the intestinal tract, respiratory tract and genitourinary system.

Tissues and organs that are characterized cellular and intracellular regeneration (liver, kidneys, lungs, smooth and skeletal muscles, autonomic nervous system, endocrine, pancreas).

Fabrics that are predominantly intracellular regeneration (myocardium) or exclusively intracellular regeneration (ganglion cells of the central nervous system). It covers the processes of restoration of macromolecules and cell organelles by assembling elementary structures or by their division (mitochondria).

In the process of evolution, 2 types of regeneration were formed physiological and reparative .

Physiological regeneration - This is a natural process of restoring the elements of the body throughout life. For example, the restoration of erythrocytes and leukocytes, the change of the epithelium of the skin, hair, the replacement of milk teeth with permanent ones. These processes are influenced by external and internal factors.

Reparative regeneration is the restoration of organs and tissues lost due to damage or injury. The process occurs after mechanical injuries, burns, chemical or radiation injuries, as well as as a result of diseases and surgical operations.

Reparative regeneration is divided into typical (homomorphosis) and atypical (heteromorphosis). In the first case, it regenerates an organ that was removed or destroyed, in the second, another organ develops in place of the removed organ.

Atypical regeneration more common in invertebrates.

Hormones stimulate regeneration pituitary gland and thyroid gland . There are several ways to regenerate:

Epimorphosis or complete regeneration - restoration of the wound surface, completion of the part to the whole (for example, the growth of a tail in a lizard, limbs in a newt).

Morphollaxis - restructuring of the remaining part of the organ to the whole, only smaller. This method is characterized by the restructuring of the new from the remnants of the old (for example, the restoration of a limb in a cockroach).

Endomorphosis - recovery due to intracellular restructuring of tissue and organ. Due to the increase in the number of cells and their size, the mass of the organ approaches the initial one.

In vertebrates, reparative regeneration occurs in the following form:

Complete regeneration - restoration of the original tissue after its damage.

Regenerative hypertrophy characteristic of internal organs. In this case, the wound surface heals with a scar, the removed area does not grow back and the shape of the organ is not restored. The mass of the remaining part of the organ increases due to an increase in the number of cells and their size and approaches the original value. So in mammals, the liver, lungs, kidneys, adrenal glands, pancreas, salivary, thyroid glands regenerate.

Intracellular compensatory hyperplasia cell ultrastructures. In this case, a scar is formed at the site of damage, and the restoration of the original mass occurs due to an increase in the volume of cells, and not their number, based on the growth (hyperplasia) of intracellular structures (nervous tissue).

Systemic mechanisms are provided by the interaction of regulatory systems: nervous, endocrine and immune .

Nervous regulation carried out and coordinated by the central nervous system. Nerve impulses, entering cells and tissues, cause not only excitation, but also regulate chemical processes, the exchange of biologically active substances. Currently, more than 50 neurohormones are known. So, in the hypothalamus, vasopressin, oxytocin, liberins and statins are produced that regulate the function of the pituitary gland. Examples of systemic manifestations of homeostasis are the maintenance of a constant temperature, blood pressure.

From the standpoint of homeostasis and adaptation, the nervous system is the main organizer of all body processes. At the heart of adaptation, balancing organisms with environmental conditions, according to N.P. Pavlov, are reflex processes. Between different levels of homeostatic regulation there is a private hierarchical subordination in the system of regulation of the internal processes of the body (Fig. 12).

hemispheric cortex and parts of the brain

feedback self-regulation

peripheral neuro-regulatory processes, local reflexes

Cellular and tissue levels of homeostasis

Rice. 12. - Hierarchical subordination in the system of regulation of the internal processes of the body.

The most primary level is the homeostatic systems of the cellular and tissue levels. Above them are peripheral nervous regulatory processes such as local reflexes. Further in this hierarchy are the systems of self-regulation of certain physiological functions with various channels of "feedback". The top of this pyramid is occupied by the cerebral cortex and the brain.

In a complex multicellular organism, both direct and feedback connections are carried out not only by nervous, but also by hormonal (endocrine) mechanisms. Each of the glands that make up the endocrine system affects the other organs of this system and, in turn, is influenced by the latter.

Endocrine mechanisms homeostasis according to B.M. Zavadsky, this is a mechanism of plus or minus interaction, i.e. balancing the functional activity of the gland with the concentration of the hormone. With a high concentration of the hormone (above normal), the activity of the gland is weakened and vice versa. This effect is carried out by the action of the hormone on the gland that produces it. In a number of glands, regulation is established through the hypothalamus and the anterior pituitary gland, especially during a stress response.

Endocrine glands can be divided into two groups in relation to their relation to the anterior pituitary gland. The latter is considered central, and the other endocrine glands are considered peripheral. This division is based on the fact that the anterior pituitary gland produces the so-called tropic hormones, which activate certain peripheral endocrine glands. In turn, the hormones of the peripheral endocrine glands act on the anterior pituitary gland, inhibiting the secretion of tropic hormones.

The reactions that provide homeostasis cannot be limited to any one endocrine gland, but captures all glands to one degree or another. The resulting reaction acquires a chain flow and spreads to other effectors. The physiological significance of hormones lies in the regulation of other body functions, and therefore the chain character should be expressed as much as possible.

Constant violations of the body's environment contribute to the preservation of its homeostasis during a long life. If you create such conditions of life under which nothing causes significant changes in the internal environment, then the organism will be completely unarmed when it encounters the environment and will soon die.

The combination of nervous and endocrine mechanisms of regulation in the hypothalamus allows for complex homeostatic reactions associated with the regulation of the visceral function of the body. The nervous and endocrine systems are the unifying mechanism of homeostasis.

An example of a general response of nervous and humoral mechanisms is a state of stress that develops under adverse living conditions and there is a threat of homeostasis disturbance. Under stress, there is a change in the state of most systems: muscular, respiratory, cardiovascular, digestive, sensory organs, blood pressure, blood composition. All these changes are a manifestation of individual homeostatic reactions aimed at increasing the body's resistance to adverse factors. The rapid mobilization of the body's forces acts as a protective reaction to a state of stress.

With "somatic stress" the task of increasing the overall resistance of the organism is solved according to the scheme shown in Figure 13.

Rice. 13 - Scheme of increasing the overall resistance of the body when

homeostasis

Homeostasis, homeoresis, homeomorphosis - characteristics of the state of the body. The system essence of the organism is manifested primarily in its ability to self-regulate in continuously changing environmental conditions. Since all organs and tissues of the body consist of cells, each of which is a relatively independent organism, the state of the internal environment of the human body is of great importance for its normal functioning. For the human body - a land creature - the environment is the atmosphere and the biosphere, while it interacts to a certain extent with the lithosphere, hydrosphere and noosphere. At the same time, most of the cells of the human body are immersed in a liquid medium, which is represented by blood, lymph and intercellular fluid. Only integumentary tissues directly interact with the human environment, all other cells are isolated from the outside world, which allows the body to largely standardize the conditions for their existence. In particular, the ability to maintain a constant body temperature of about 37 ° C ensures the stability of metabolic processes, since all the biochemical reactions that make up the essence of metabolism are very temperature dependent. It is equally important to maintain a constant tension of oxygen, carbon dioxide, concentration of various ions, etc. in the liquid media of the body. Under normal conditions of existence, including during adaptation and activity, small deviations of such parameters occur, but they are quickly eliminated, the internal environment of the body returns to a stable norm. Great French physiologist of the 19th century. Claude Bernard argued: "The constancy of the internal environment is a prerequisite for a free life." The physiological mechanisms that ensure the maintenance of the constancy of the internal environment are called homeostatic, and the phenomenon itself, which reflects the body's ability to self-regulate the internal environment, is called homeostasis. This term was introduced in 1932 by W. Cannon, one of those physiologists of the 20th century, who, along with N.A. Bernstein, P.K. Anokhin and N. Wiener, stood at the origins of the science of control - cybernetics. The term "homeostasis" is used not only in physiological, but also in cybernetic research, since it is precisely the maintenance of the constancy of any characteristics of a complex system that is the main goal of any control.

Another remarkable researcher, K. Waddington, drew attention to the fact that the body is able to maintain not only the stability of its internal state, but also the relative constancy of dynamic characteristics, i.e., the flow of processes over time. This phenomenon, by analogy with homeostasis, was called homeoresis. It is of particular importance for a growing and developing organism and lies in the fact that the organism is able to maintain (within certain limits, of course) the "channel of development" in the course of its dynamic transformations. In particular, if a child, due to an illness or a sharp deterioration in living conditions caused by social reasons (war, earthquake, etc.), lags significantly behind his normally developing peers, this does not mean that such a lag is fatal and irreversible. If the period of adverse events ends and the child receives adequate conditions for development, then both in terms of growth and the level of functional development, he soon catches up with his peers and in the future does not differ significantly from them. This explains the fact that children who have had a serious illness at an early age often grow up into healthy and proportionately built adults. Homeoresis plays an important role both in the management of ontogenetic development and in the processes of adaptation. Meanwhile, the physiological mechanisms of homeoresis are still insufficiently studied.

The third form of self-regulation of body constancy is homeomorphosis - the ability to maintain the invariance of the form. This characteristic is more characteristic of an adult organism, since growth and development are incompatible with the invariance of form. Nevertheless, if we consider short periods of time, especially during periods of growth inhibition, then in children it is possible to detect the ability to homeomorphosis. We are talking about the fact that in the body there is a continuous change of generations of its constituent cells. Cells do not live long (the only exception is nerve cells): the normal lifespan of body cells is weeks or months. Nevertheless, each new generation of cells almost exactly repeats the shape, size, location and, accordingly, the functional properties of the previous generation. Special physiological mechanisms prevent significant changes in body weight in conditions of starvation or overeating. In particular, during starvation, the digestibility of nutrients increases sharply, and during overeating, on the contrary, most of the proteins, fats and carbohydrates that come with food are "burned" without any benefit to the body. It has been proven (N.A. Smirnova) that in an adult, sharp and significant changes in body weight (mainly due to the amount of fat) in any direction are sure signs of a breakdown in adaptation, overstrain and indicate a functional dysfunction of the body. The child's body becomes especially sensitive to external influences during periods of the most rapid growth. Violation of homeomorphosis is the same unfavorable sign as violations of homeostasis and homeoresis.

The concept of biological constants. The body is a complex of a huge number of a wide variety of substances. In the process of vital activity of body cells, the concentration of these substances can change significantly, which means a change in the internal environment. It would be unthinkable if the control systems of the body were forced to monitor the concentration of all these substances, i.e. have a lot of sensors (receptors), continuously analyze the current state, make management decisions and monitor their effectiveness. Neither the information nor the energy resources of the body would be enough for such a regime of control of all parameters. Therefore, the body is limited to monitoring a relatively small number of the most significant indicators that must be maintained at a relatively constant level for the well-being of the vast majority of body cells. These most rigidly homeostatic parameters thus turn into "biological constants", and their invariance is ensured by sometimes quite significant fluctuations of other parameters that do not belong to the category of homeostatic ones. Thus, the levels of hormones involved in the regulation of homeostasis can change tenfold in the blood, depending on the state of the internal environment and the impact of external factors. At the same time, homeostatic parameters change only by 10-20%.

The most important biological constants. Among the most important biological constants, for the maintenance of which at a relatively unchanged level, various physiological systems of the body are responsible, we should mention body temperature, blood glucose level, content of H + ions in body fluids, partial tension of oxygen and carbon dioxide in tissues.

Disease as a symptom or consequence of homeostasis disorders. Almost all human diseases are associated with a violation of homeostasis. So, for example, in many infectious diseases, as well as in the case of inflammatory processes, temperature homeostasis is sharply disturbed in the body: fever (fever), sometimes life-threatening, occurs. The reason for such a violation of homeostasis may lie both in the features of the neuroendocrine reaction, and in violations of the activity of peripheral tissues. In this case, the manifestation of the disease - fever - is a consequence of a violation of homeostasis.

Usually, feverish conditions are accompanied by acidosis - a violation of the acid-base balance and a shift in the reaction of body fluids to the acid side. Acidosis is also characteristic of all diseases associated with the deterioration of the cardiovascular and respiratory systems (diseases of the heart and blood vessels, inflammatory and allergic lesions of the bronchopulmonary system, etc.). Often, acidosis accompanies the first hours of a newborn's life, especially if normal breathing did not begin immediately after birth. To eliminate this condition, the newborn is placed in a special chamber with a high oxygen content. Metabolic acidosis with heavy muscular exertion can occur in people of any age and manifests itself in shortness of breath and increased sweating, as well as painful sensations in the muscles. After completion of work, the state of acidosis can persist from several minutes to 2-3 days, depending on the degree of fatigue, fitness and the effectiveness of homeostatic mechanisms.

Very dangerous diseases that lead to a violation of water-salt homeostasis, such as cholera, in which a huge amount of water is removed from the body and tissues lose their functional properties. Many kidney diseases also lead to a violation of water-salt homeostasis. As a result of some of these diseases, alkalosis can develop - an excessive increase in the concentration of alkaline substances in the blood and an increase in pH (shift to the alkaline side).

In some cases, minor but long-term disturbances in homeostasis can cause the development of certain diseases. So, there is evidence that excessive consumption of sugar and other sources of carbohydrates that disrupt glucose homeostasis leads to damage to the pancreas, as a result, a person develops diabetes. Also dangerous is the excessive consumption of table and other mineral salts, hot spices, etc., which increase the load on the excretory system. Kidneys May not cope with the abundance of substances that need to be removed from the body, resulting in a violation of water-salt homeostasis. One of its manifestations is edema - the accumulation of fluid in the soft tissues of the body. The cause of edema usually lies either in the insufficiency of the cardiovascular system, or in violations of the kidneys and, as a result, mineral metabolism.

The concept was introduced by the American psychologist W.B. Cannon in relation to any processes that change the initial state or a series of states, initiating new processes aimed at restoring the initial conditions. The mechanical homeostat is the thermostat. The term is used in physiological psychology to describe a number of complex mechanisms operating in the autonomic nervous system to regulate factors such as body temperature, biochemistry, blood pressure, fluid balance, metabolism, and so on. for example, a change in body temperature initiates a variety of processes such as shivering, increasing metabolism, increasing or retaining heat until normal temperature is reached. Examples of homeostatic psychological theories are balance theory (Heider, 1983), congruence theory (Osgood, Tannenbaum, 1955), cognitive dissonance theory (Festinger, 1957), symmetry theory (Newcomb, 1953), etc. As an alternative to the homeostatic approach, a heterostatic approach is proposed. an approach that assumes the fundamental possibility of the existence of balance states within a single whole (see heterostasis).

HOMEOSTASIS

Homeostasis) - maintaining a balance between opposing mechanisms or systems; the basic principle of physiology, which should also be considered the basic law of mental behavior.

HOMEOSTASIS

homeostasis The tendency of organisms to maintain their permanent state. According to Cannon (1932), the originator of the term: "Organisms, composed of matter characterized by the highest degree of variability and instability, have somehow mastered the means of maintaining permanence and maintaining stability under conditions that should reasonably be regarded as absolutely destructive." Freud's PLEASURE PRINCIPLE and Fechner's CONSTANT PRINCIPLE used by him are usually considered as psychological concepts analogous to the physiological concept of homeostasis, i.e. they suggest that there is a programmed tendency to maintain psychological VOLTAGE at a constant optimal level, similar to the tendency for the body to maintain a constant blood chemistry, temperature, etc.

HOMEOSTASIS

a mobile equilibrium state of a system, maintained by its counteraction to disturbing external and internal factors. Maintaining the constancy of various physiological parameters of the body. The concept of homeostasis was originally developed in physiology to explain the constancy of the internal environment of the body and the stability of its basic physiological functions. This idea was developed by the American physiologist W. Cannon in his doctrine of the wisdom of the body as an open system that continuously maintains stability. Receiving signals about changes that threaten the system, the body turns on devices that continue to work until it is possible to return it to an equilibrium state, to the previous values of the parameters. The principle of homeostasis passed from physiology to cybernetics and other sciences, including psychology, acquiring a more general meaning of the principle of a systematic approach and self-regulation based on feedback. The idea that every system strives to maintain stability was transferred to the interaction of the organism with the environment. Such a transfer is typical, in particular:

1) for neobehaviorism, which believes that a new motor reaction is fixed due to the release of the body from a need that has violated its homeostasis;

2) for the concept of J. Piaget, who believes that mental development occurs in the process of balancing the body with the environment;

3) for K. Levin's field theory, according to which motivation arises in a non-equilibrium "system of stresses";

4) for Gestalt psychology, which notes that if the balance of the components of the mental system is disturbed, it seeks to restore it. However, the principle of homeostasis, explaining the phenomenon of self-regulation, cannot reveal the source of changes in the psyche and its activity.

HOMEOSTASIS

Greek homeios - similar, similar, statis - standing, immobility). The mobile, but stable balance of any system (biological, mental), due to its opposition to internal and external factors that violate this balance (see Cannon's thalamic theory of emotions. The principle of G. is widely used in physiology, cybernetics, psychology, it explains the adaptive ability Mental G. maintains optimal conditions for the functioning of the brain and nervous system in the process of life.

HOMEOSTASIS(IS)

from the Greek homoios - similar + stasis - standing; letters, meaning "to be in the same state").

1. In the narrow (physiological) sense, G. - the processes of maintaining the relative constancy of the main characteristics of the internal environment of the body (for example, the constancy of body temperature, blood pressure, blood sugar, etc.) in a wide range of environmental conditions. A large role in G. is played by the joint activity of the vegetative n. c, hypothalamus and brain stem, as well as the endocrine system, while partly neurohumoral regulation G. It is carried out "autonomously" from the psyche and behavior. The hypothalamus "decides" at what G.'s violation it is necessary to turn to the highest forms of adaptation and start the mechanism of biological motivation of behavior (see the Drive reduction hypothesis, Needs).

The term "G." introduced Amer. physiologist Walter Cannon (Cannon, 1871-1945) in 1929, however, the concept of the internal environment and the concept of its constancy were developed much earlier than fr. physiologist Claude Bernard (Bernard, 1813-1878).

2. In a broad sense, the concept of "G." apply to a variety of systems (biocenoses, populations, individuals, social systems, etc.). (B. M.)

homeostasis

homeostasis) In order to survive and move freely in changing and often hostile environmental conditions, complex organisms need to maintain their internal environment relatively constant. This inner constancy was called "G" by Walter B. Cannon. Cannon described his findings as examples of steady state maintenance in open systems. In 1926, he proposed the term "G" for such a steady state. and proposed a system of postulates concerning its nature, which was subsequently expanded in preparation for the publication of a review of the homeostatic and regulatory mechanisms known by that time. The organism, Cannon argued, through homeostatic reactions is able to maintain the stability of the intercellular fluid (fluid matrix), thus controlling and regulating. body temperature, blood pressure, and other parameters of the internal environment, the maintenance of which within certain limits is necessary for life. G. tzh is maintained in relation to the levels of supply of substances necessary for the normal functioning of cells. The concept of G. proposed by Kennon appeared in the form of a set of provisions concerning the existence, nature and principles of self-regulating systems. He emphasized that complex living beings are open systems formed from changing and unstable components, constantly subject to perturbing external influences due to this openness. Thus, these ever-changing systems must nevertheless maintain constancy with respect to the environment in order to maintain conditions favorable to life. Correction in such systems should occur continuously. Therefore, G. characterizes rather than an absolutely stable state. The concept of an open system challenged all traditional notions of an adequate unit of organism analysis. If the heart, lungs, kidneys, and blood, for example, are parts of a self-regulating system, then their action or function cannot be understood from a study of each of them individually. A full understanding is possible only on the basis of knowing how each of these parts operates in view of others. The concept of an open system also challenges all traditional views on causality, offering complex reciprocal determination instead of simple sequential or linear causality. Thus, G. has become a new perspective both for considering the behavior of various kinds of systems, and for understanding people as elements of open systems. See also Adaptation, General Adaptation Syndrome, General Systems, Lens Model, Soul-Body Relationship Question R. Enfield

HOMEOSTASIS

the general principle of self-regulation of living organisms, formulated by Cannon in 1926. Perls emphasizes the importance of this concept in his work "The Gestalt Approach and Eye Witness to Therapy", begun in 1950, completed in 1970 and published after his death in 1973.

homeostasis

The process by which the body maintains balance in its internal physiological environment. Through homeostatic impulses, the urge to eat, drink and regulate body temperature occurs. For example, a decrease in body temperature initiates many processes (such as shivering) that help restore normal temperature. Thus, homeostasis initiates other processes that act as regulators and restore the optimal state. As an analogue, you can bring a central heating system with thermostatic control. When the room temperature falls below the values set in the thermostat, it turns on the steam boiler, which pumps hot water into the heating system, raising the temperature. When the temperature in the room reaches a normal level, the thermostat turns off the steam boiler.

HOMEOSTASIS

homeostasis) - the physiological process of maintaining the constancy of the internal environment of the body (ed.), in which various parameters of the body (for example, blood pressure, body temperature, acid-base balance) are maintained in balance, despite changes in environmental conditions. - Homeostatic.

homeostasis

Word formation. Comes from the Greek. homoios - similar + stasis - immobility.

Specificity. The process by which a relative constancy of the internal environment of the body is achieved (constancy of body temperature, blood pressure, blood sugar concentration). As a separate mechanism, neuropsychic homeostasis can be distinguished, due to which the preservation and maintenance of optimal conditions for the functioning of the nervous system in the process of implementing various forms of activity is ensured.

HOMEOSTASIS

Literally translated from Greek means the same state. American physiologist W.B. Cannon introduced this term to refer to any process that changes an existing condition or set of circumstances and, as a result, initiates other processes that perform regulatory functions and restore the original state. The thermostat is a mechanical homeostat. This term is used in physiological psychology to refer to a number of complex biological mechanisms that operate through the autonomic nervous system, regulating factors such as body temperature, body fluids and their physical and chemical properties, blood pressure, water balance, metabolism, etc. For example, a decrease in body temperature initiates a number of processes, such as shivering, piloerection, and an increase in metabolism, which cause and maintain a high temperature until a normal temperature is reached.

HOMEOSTASIS

from the Greek homoios - similar + stasis - state, immobility) - a type of dynamic balance, characteristic of complex self-regulating systems and consisting in maintaining parameters essential for the system within acceptable limits. The term "G." proposed by the American physiologist W. Cannon in 1929 to describe the state of the human body, animals and plants. Then this concept became widespread in cybernetics, psychology, sociology, etc. The study of homeostatic processes involves the selection of: 1) parameters, significant changes in which disrupt the normal functioning of the system; 2) the limits of the permissible change of these parameters under the influence of the conditions of the external and internal environment; 3) a set of specific mechanisms that begin to function when the values of variables go beyond these boundaries (B. G. Yudin, 2001). Each conflict reaction of any of the parties in the event of the emergence and development of a conflict is nothing more than the desire to maintain its G. The parameter, the change of which triggers the conflict mechanism, is the damage predicted as a consequence of the actions of the opponent. The dynamics of the conflict and the pace of its escalation are regulated by feedback: the reaction of one side of the conflict to the actions of the other side. For the last 20 years Russia has been developing as a system with lost, blocked or extremely weakened feedback. Therefore, the behavior of the state and society in the conflicts of the given period, which destroyed the national economy of the country, is irrational. The application of G.'s theory to the analysis and regulation of social conflicts can significantly increase the effectiveness of the work of domestic conflictologists.

homeostasis(ancient Greek ὁμοιοστάσις from ὅμοιος - the same, similar and στάσις - standing, immobility) - self-regulation, the ability of an open system to maintain the constancy of its internal state through coordinated reactions aimed at maintaining dynamic balance. The desire of the system to reproduce itself, to restore the lost balance, to overcome the resistance of the external environment. Population homeostasis is the ability of a population to maintain a certain number of its individuals for a long time.

General information

properties of homeostasis

instability
Striving for balance
unpredictability

Regulation of the level of basic metabolism depending on the diet.

Main article: Feedback

Ecological homeostasis

Biological homeostasis

Cellular homeostasis

The regulation of the chemical activity of the cell is achieved through a number of processes, among which the change in the structure of the cytoplasm itself, as well as the structure and activity of enzymes, is of particular importance. Autoregulation depends on temperature, the degree of acidity, the concentration of the substrate, the presence of certain macro- and microelements. Cellular mechanisms of homeostasis are aimed at restoring naturally dead cells of tissues or organs in case of violation of their integrity.

Regeneration-the process of updating the structural elements of the body and restoring their number after damage, aimed at providing the necessary functional activity

Depending on the regenerative response, tissues and organs of mammals can be divided into 3 groups:

1) tissues and organs that are characterized by cellular regeneration (bones, loose connective tissue, hematopoietic system, endothelium, mesothelium, mucous membranes of the gastrointestinal tract, respiratory tract and genitourinary system)

2) tissues and organs that are characterized by cellular and intracellular regeneration (liver, kidneys, lungs, smooth and skeletal muscles, autonomic nervous system, pancreas, endocrine system)

3) tissues, which are characterized mainly or exclusively by intracellular regeneration (myocardium and ganglion cells of the central nervous system)

In the process of evolution, 2 types of regeneration were formed: physiological and reparative.

Other areas

The actuary can talk about risk homeostasis in which, for example, people who have an anti-lock braking system installed in their car are not in a safer position than those who do not have it installed, because these people unconsciously compensate for a safer car by risky driving. This happens because some of the holding mechanisms - such as fear - stop working.

stress homeostasis

Examples

thermoregulation
- Skeletal muscle trembling may begin if the body temperature is too low.
Chemical regulation

Sources

1. O.-Ya.L.Bekish. Medical biology. - Minsk: Urajay, 2000. - 520 p. - ISBN 985-04-0336-5.

Topic № 13. Homeostasis, mechanisms of its regulation.

The body as an open self-regulating system.

A living organism is an open system that has a connection with the environment through the nervous, digestive, respiratory, excretory systems, etc.

The body is an open, dynamic system. In a constantly changing environment, the body maintains a stable state for a certain time.

The concept of homeostasis. General patterns of homeostasis of living systems.

maintaining known steady state levels;

elimination or limitation of harmful factors;

development or preservation of optimal forms of interaction between the organism and the environment in the changed conditions of its existence. All these processes determine adaptation.

The main components of homeostasis were defined by C. Bernard, and they can be divided into three groups:

A. Substances that provide cellular needs:

Substances necessary for the formation of energy, for growth and recovery - glucose, proteins, fats.

NaCl, Ca and other inorganic substances.

Oxygen.

internal secretion.

B. Environmental factors affecting cellular activity:

osmotic pressure.

Temperature.

Hydrogen ion concentration (pH).

B. Mechanisms that ensure structural and functional unity:

Heredity.

Regeneration.

immunobiological reactivity.

Rice. 10 - General scheme of homeostasis of living systems

The output variables depend on the input variables and the laws of the system behavior.

General principle of homeostatic response(Anokhin: "Theory of functional systems"):

deviation from the initial level → signal → activation of regulatory mechanisms based on the feedback principle → correction of changes (normalization).

Mechanisms of regulation of homeostasis at the molecular-genetic, cellular, organismal, population-species and biospheric levels.

Regulatory homeostatic mechanisms function at the gene, cellular and systemic (organismic, population-species and biospheric) levels.

Syngeneic transplant carried out in identical twins with the same genotype.

Xenotransplantation Donor and recipient belong to different types of organisms. This type of transplantation succeeds in some invertebrates, but such transplants do not take root in higher animals.

Antigens of the SD group are determined by serological methods and are determined by the genes of 3 subloci of the HLA system: HLA-A; HLA-B; HLA-C.

Rice. 11 - HLA main human histocompatibility genetic system

LD - antigens are controlled by the HLA-D sublocus of the sixth chromosome, and are determined by the method of mixed cultures of leukocytes.

Tissues, according to their regenerative capacity, are divided into 3 groups:

Tissues and organs that are characterized cellular and intracellular regeneration (liver, kidneys, lungs, smooth and skeletal muscles, autonomic nervous system, endocrine, pancreas).

In the process of evolution, 2 types of regeneration were formed physiological and reparative .

Atypical regeneration more common in invertebrates.

Hormones stimulate regeneration pituitary gland and thyroid gland . There are several ways to regenerate:

Epimorphosis or complete regeneration - restoration of the wound surface, completion of the part to the whole (for example, the growth of a tail in a lizard, limbs in a newt).

Endomorphosis - recovery due to intracellular restructuring of tissue and organ. Due to the increase in the number of cells and their size, the mass of the organ approaches the initial one.

In vertebrates, reparative regeneration occurs in the following form:

Complete regeneration - restoration of the original tissue after its damage.

Intracellular compensatory hyperplasia cell ultrastructures. In this case, a scar is formed at the site of damage, and the restoration of the initial mass occurs due to an increase in the volume of cells, and not their number, based on the growth (hyperplasia) of intracellular structures (nervous tissue).

Systemic mechanisms are provided by the interaction of regulatory systems: nervous, endocrine and immune .

hemispheric cortex and parts of the brain

feedback self-regulation

peripheral neuro-regulatory processes, local reflexes

Cellular and tissue levels of homeostasis

Rice. 12. - Hierarchical subordination in the system of regulation of the internal processes of the body.

With "somatic stress" the task of increasing the overall resistance of the organism is solved according to the scheme shown in Figure 13.

Rice. 13 - Scheme of increasing the overall resistance of the body when

Homeostasis - what is it? The concept of homeostasis

Homeostasis is a self-regulating process in which all biological systems strive to maintain stability during the period of adaptation to certain conditions that are optimal for survival. Any system, being in dynamic equilibrium, strives to achieve a stable state that resists external factors and stimuli.

The concept of homeostasis

All body systems must work together to maintain proper homeostasis within the body. Homeostasis is the regulation of body temperature, water content, and carbon dioxide levels. For example, diabetes mellitus is a condition in which the body cannot regulate blood glucose levels.

Homeostasis is a term that is used both to describe the existence of organisms in an ecosystem and to describe the successful functioning of cells within an organism. Organisms and populations can maintain homeostasis while maintaining stable birth and death rates.

Feedback

Feedback is a process that occurs when the body's systems need to be slowed down or completely stopped. When a person eats, food enters the stomach and digestion begins. In between meals, the stomach should not work. The digestive system works with a series of hormones and nerve impulses to stop and start acid production in the stomach.

Another example of negative feedback can be observed in the case of an increase in body temperature. The regulation of homeostasis is manifested by sweating, a protective reaction of the body to overheating. In this way, the rise in temperature is stopped and the problem of overheating is neutralized. In case of hypothermia, the body also provides for a number of measures taken in order to warm up.

Maintaining internal balance

Homeostasis can be defined as a property of an organism or system that helps it to maintain given parameters within the normal range of values. This is the key to life, and the wrong balance in maintaining homeostasis can lead to diseases such as hypertension and diabetes.

Homeostasis is a key element in understanding how the human body works. Such a formal definition characterizes a system that regulates its internal environment and seeks to maintain the stability and regularity of all processes occurring in the body.

Homeostatic regulation: body temperature

Body temperature control in humans is a good example of homeostasis in a biological system. When a person is healthy, their body temperature fluctuates around + 37°C, but various factors can affect this value, including hormones, metabolic rate, and various diseases that cause fever.

In the body, temperature regulation is controlled in a part of the brain called the hypothalamus. Through the bloodstream to the brain, temperature signals are received, as well as the analysis of the results of data on the frequency of respiration, blood sugar and metabolism. The loss of heat in the human body also contributes to reduced activity.

Water-salt balance

No matter how much water a person drinks, the body does not swell like a balloon, and the human body does not shrink like raisins if you drink very little. Probably, someone once thought about it at least once. One way or another, the body knows how much fluid needs to be stored to maintain the desired level.

The concentration of salt and glucose (sugar) in the body is maintained at a constant level (in the absence of negative factors), the amount of blood in the body is about 5 liters.

Blood sugar regulation

Glucose is a type of sugar found in the blood. The human body must maintain proper glucose levels in order for a person to remain healthy. When glucose levels get too high, the pancreas releases the hormone insulin.

If the blood glucose level drops too low, the liver converts the glycogen in the blood, thereby raising the sugar level. When pathogenic bacteria or viruses enter the body, it begins to fight the infection before the pathogenic elements can lead to any health problems.

Pressure under control

Maintaining healthy blood pressure is also an example of homeostasis. The heart can sense changes in blood pressure and send signals to the brain for processing. Next, the brain sends a signal back to the heart with instructions on how to respond correctly. If the blood pressure is too high, it must be lowered.

How is homeostasis achieved?

How does the human body regulate all systems and organs and compensate for the ongoing changes in the environment? This is due to the presence of many natural sensors that control temperature, blood salt composition, blood pressure and many other parameters. These detectors send signals to the brain, to the main control center, in case some values deviate from the norm. After that, compensatory measures are launched to restore the normal state.

Maintaining homeostasis is incredibly important for the body. The human body contains a certain amount of chemicals known as acids and alkalis, and their proper balance is essential for the optimal functioning of all organs and body systems. The level of calcium in the blood must be maintained at the proper level. Because breathing is involuntary, the nervous system provides the body with much-needed oxygen. When toxins enter your bloodstream, they disrupt the body's homeostasis. The human body responds to this disturbance with the help of the urinary system.

It is important to emphasize that the body's homeostasis works automatically if the system functions normally. For example, a reaction to heat - the skin turns red, because its small blood vessels automatically dilate. Trembling is a response to being cold. Thus, homeostasis is not a set of organs, but the synthesis and balance of bodily functions. Together, this allows you to maintain the entire body in a stable state.

9.4. The concept of homeostasis. General patterns of homeostasis of living systems

Despite the fact that a living organism is an open system that exchanges matter and energy with the environment and exists in unity with it, it retains itself in time and space as a separate biological unit, retains its structure (morphology), behavioral reactions, specific physical -chemical conditions in cells, tissue fluid. The ability of living systems to withstand changes and maintain the dynamic constancy of composition and properties is called homeostasis. The term "homeostasis" was proposed by W. Cannon in 1929. However, the idea of the existence of physiological mechanisms that ensure the maintenance of the constancy of the internal environment of organisms was expressed in the second half of the 19th century by C. Bernard.

Homeostasis has improved in the course of evolution. Multicellular organisms have an internal environment in which cells of various organs and tissues are located. Then specialized organ systems (circulation, nutrition, respiration, excretion, etc.) were formed, which are involved in ensuring homeostasis at all levels of organization (molecular, subcellular, cellular, tissue, organ and organism). The most perfect mechanisms of homeostasis were formed in mammals, which contributed to a significant expansion of the possibilities of their adaptation to the environment. Mechanisms and types of homeostasis evolved in the process of long-term evolution, being fixed genetically. The appearance in the body of alien genetic information, which is often introduced by bacteria, viruses, cells of other organisms, as well as its own mutated cells, can significantly disrupt the body's homeostasis. As a protection against alien genetic information, the penetration of which into the body and its subsequent implementation would lead to poisoning with toxins (foreign proteins), such a type of homeostasis arose as genetic homeostasis, which ensures the genetic constancy of the internal environment of the body. It is based on immunological mechanisms, including non-specific and specific protection of the body's own integrity and individuality. Non-specific mechanisms underlie innate, constitutional, species immunity, as well as individual nonspecific resistance. These include the barrier function of the skin and mucous membranes, the bactericidal action of the secretion of sweat and sebaceous glands, the bactericidal properties of the contents of the stomach and intestines, lysozyme secretion of the salivary and lacrimal glands. If the organisms penetrate into the internal environment, they are eliminated during the inflammatory reaction, which is accompanied by enhanced phagocytosis, as well as the virusostatic effect of interferon (a protein with a molecular weight of 25,000 - 110,000).

Specific immunological mechanisms form the basis of acquired immunity, carried out by the immune system, which recognizes, processes and eliminates foreign antigens. Humoral immunity is carried out through the formation of antibodies circulating in the blood. The basis of cellular immunity is the formation of T-lymphocytes, the appearance of long-lived T- and B-lymphocytes of "immunological memory", the occurrence of allergies (hypersensitivity to a specific antigen). In humans, protective reactions come into effect only at the 2nd week of life, reach their highest activity by the age of 10, decrease slightly from 10 to 20 years, remain approximately at the same level from 20 to 40 years, then gradually fade away.

Immunological defense mechanisms are a serious obstacle in organ transplantation, causing graft resorption. The most successful are currently the results of autotransplantation (transplantation of tissues within the body) and allotransplantation between identical twins. They are much less successful in interspecies transplantation (heterotransplantation or xenotransplantation).

Another type of homeostasis is biochemical homeostasis helps to maintain the constancy of the chemical composition of the liquid extracellular (internal) environment of the body (blood, lymph, tissue fluid), as well as the constancy of the chemical composition of the cytoplasm and plasmolemma of cells. Physiological homeostasis ensures the constancy of the processes of vital activity of the body. Thanks to him, isoosmia (the constancy of the content of osmotically active substances), isothermia (maintenance of the body temperature of birds and mammals within certain limits), etc., have arisen and are being improved. Structural homeostasis ensures the constancy of the structure (morphological organization) at all levels (molecular, subcellular, cellular, etc.) of the organization of the living.

Population homeostasis ensures the constancy of the number of individuals in the population. Biocenotic homeostasis contributes to the constancy of the species composition and number of individuals in biocenoses.

Due to the fact that the body functions and interacts with the environment as a single system, the processes underlying various types of homeostatic reactions are closely interconnected with each other. Separate homeostatic mechanisms are combined and implemented in a holistic adaptive reaction of the body as a whole. Such association is carried out due to the activity (function) of regulatory integrating systems (nervous, endocrine, immune). The most rapid changes in the state of the regulated object are provided by the nervous system, which is associated with the speed of the processes of occurrence and conduction of a nerve impulse (from 0.2 to 180 m/sec). The regulatory function of the endocrine system is carried out more slowly, as it is limited by the rate of release of hormones by the glands and their transfer in the bloodstream. However, the effect of hormones accumulating in it on a regulated object (organ) is much longer than with nervous regulation.

The body is a self-regulating living system. Due to the presence of homeostatic mechanisms, the body is a complex self-regulating system. The principles of existence and development of such systems are studied by cybernetics, while those of living systems are studied by biological cybernetics.

Self-regulation of biological systems is based on the principle of direct and feedback.

Information about the deviation of the controlled value from the set level is transmitted to the controller through the feedback channels and changes its activity in such a way that the controlled value returns to the initial (optimal) level (Fig. 122). Feedback can be negative(when the controlled value has deviated in a positive direction (synthesis of a substance, for example, has increased excessively)) and put-

Rice. 122. Scheme of direct and feedback in a living organism:

P - regulator (nerve center, endocrine gland); RO - regulated object (cell, tissue, organ); 1 – optimal functional activity of RO; 2 - reduced functional activity of RO with positive feedback; 3 - increased functional activity of RO with negative feedback

body(when the controlled value has deviated in the negative direction (the substance is synthesized in insufficient quantity)). This mechanism, as well as more complex combinations of several mechanisms, take place at different levels of organization of biological systems. As an example of their functioning at the molecular level, one can point to the inhibition of a key enzyme with excessive formation of the final product or the repression of enzyme synthesis. At the cellular level, the mechanisms of direct and feedback provide hormonal regulation and optimal density (number) of the cell population. A manifestation of direct and feedback at the level of the body is the regulation of blood glucose. In a living organism, the mechanisms of automatic regulation and control (studied by biocybernetics) are especially complex. The degree of their complexity contributes to an increase in the level of "reliability" and stability of living systems in relation to environmental changes.

The mechanisms of homeostasis are duplicated at different levels. This in nature realizes the principle of multi-loop regulation of systems. The main circuits are represented by cellular and tissue homeostatic mechanisms. They have a high degree of automatism. The main role in the control of cellular and tissue homeostatic mechanisms belongs to genetic factors, local reflex influences, chemical and contact interactions between cells.

The mechanisms of homeostasis undergo significant changes throughout human ontogenesis. Only 2 weeks after birth

Rice. 123. Options for loss and recovery in the body

biological defense reactions come into play (cells are formed that provide cellular and humoral immunity), and their effectiveness continues to increase by the age of 10. During this period, the mechanisms of protection against alien genetic information are improved, and the maturity of the nervous and endocrine regulatory systems also increases. The mechanisms of homeostasis reach the greatest reliability in adulthood, by the end of the period of development and growth of the organism (19-24 years). The aging of the body is accompanied by a decrease in the effectiveness of the mechanisms of genetic, structural, physiological homeostasis, a weakening of the regulatory influences of the nervous and endocrine systems.

5. Homeostasis.

An organism can be defined as a physicochemical system that exists in the environment in a stationary state. It is this ability of living systems to maintain a stationary state in a continuously changing environment that determines their survival. To ensure a steady state, all organisms - from the morphologically simplest to the most complex - have developed a variety of anatomical, physiological and behavioral adaptations that serve the same purpose - to maintain the constancy of the internal environment.

For the first time, the idea that the constancy of the internal environment provides optimal conditions for the life and reproduction of organisms was expressed in 1857 by the French physiologist Claude Bernard. Throughout his scientific activity, Claude Bernard was struck by the ability of organisms to regulate and maintain, within fairly narrow limits, such physiological parameters as body temperature or water content in it. He summarized this idea of self-regulation as the basis of physiological stability in the form of the classic statement: "The constancy of the internal environment is a prerequisite for a free life."

Claude Bernard emphasized the distinction between the external environment in which organisms live and the internal environment in which their individual cells reside, and understood the importance of keeping the internal environment unchanged. For example, mammals are able to maintain body temperature despite fluctuations in ambient temperature. If it gets too cold, the animal may move to a warmer or more sheltered place, and if this is not possible, self-regulatory mechanisms come into play that increase body temperature and prevent heat loss. The adaptive significance of this lies in the fact that the organism as a whole functions more efficiently, since the cells of which it is composed are in optimal conditions. Self-regulation systems operate not only at the level of the organism, but also at the level of cells. An organism is the sum of its constituent cells, and the optimal functioning of the organism as a whole depends on the optimal functioning of its constituent parts. Any self-organizing system maintains the constancy of its composition - qualitative and quantitative. This phenomenon is called homeostasis, and it is common to most biological and social systems. The term homeostasis was introduced in 1932 by the American physiologist Walter Cannon.

homeostasis(Greek homoios - similar, the same; stasis-state, immobility) - the relative dynamic constancy of the internal environment (blood, lymph, tissue fluid) and the stability of basic physiological functions (blood circulation, respiration, thermoregulation, metabolism, etc. ) of humans and animals. Regulatory mechanisms that maintain the physiological state or properties of cells, organs and systems of the whole organism at an optimal level are called homeostatic. Historically and genetically, the concept of homeostasis has biological and biomedical prerequisites. There it is correlated as a final process, a period of life with a separate isolated organism or a human individual as a purely biological phenomenon. The finiteness of existence and the need to fulfill one's destiny - reproduction of one's own kind - allow one to determine the survival strategy of an individual organism through the concept of "preservation". "Preservation of structural and functional stability" is the essence of any homeostasis, controlled by a homeostat or self-regulating.

As you know, a living cell is a mobile, self-regulating system. Its internal organization is supported by active processes aimed at limiting, preventing or eliminating shifts caused by various influences from the environment and the internal environment. The ability to return to the original state after a deviation from a certain average level, caused by one or another "disturbing" factor, is the main property of the cell. A multicellular organism is a holistic organization, the cellular elements of which are specialized to perform various functions. Interaction within the body is carried out by complex regulatory, coordinating and correlating mechanisms with the participation of nervous, humoral, metabolic and other factors. Many individual mechanisms that regulate intra- and intercellular relationships, in some cases, have mutually opposite effects that balance each other. This leads to the establishment of a mobile physiological background (physiological balance) in the body and allows the living system to maintain relative dynamic constancy, despite changes in the environment and shifts that occur during the life of the organism.

As studies show, the methods of regulation existing in living organisms have many features in common with regulatory devices in non-living systems, such as machines. In both cases, stability is achieved through a certain form of management.

The very concept of homeostasis does not correspond to the concept of stable (not fluctuating) balance in the body - the principle of balance is not applicable to complex physiological and biochemical processes occurring in living systems. It is also wrong to oppose homeostasis to rhythmic fluctuations in the internal environment. Homeostasis in a broad sense covers the issues of cyclic and phase flow of reactions, compensation, regulation and self-regulation of physiological functions, the dynamics of the interdependence of nervous, humoral and other components of the regulatory process. The boundaries of homeostasis can be rigid and plastic, vary depending on individual age, gender, social, professional and other conditions.

Of particular importance for the life of the organism is the constancy of the composition of the blood - the liquid basis of the body (fluidmatrix), according to W. Cannon. The stability of its active reaction (pH), osmotic pressure, ratio of electrolytes (sodium, calcium, chlorine, magnesium, phosphorus), glucose content, number of formed elements, etc. is well known. For example, blood pH, as a rule, does not beyond 7.35-7.47. Even severe disorders of acid-base metabolism with a pathological accumulation of acids in the tissue fluid, for example, in diabetic acidosis, have very little effect on the active reaction of the blood. Despite the fact that the osmotic pressure of blood and tissue fluid is subject to continuous fluctuations due to the constant supply of osmotically active products of interstitial metabolism, it remains at a certain level and changes only in some severe pathological conditions. Maintaining a constant osmotic pressure is of paramount importance for water metabolism and maintaining ionic balance in the body. The greatest constancy is the concentration of sodium ions in the internal environment. The content of other electrolytes also fluctuates within narrow limits. The presence of a large number of osmoreceptors in tissues and organs, including the central nervous formations (hypothalamus, hippocampus), and a coordinated system of regulators of water metabolism and ionic composition allows the body to quickly eliminate shifts in the osmotic blood pressure that occur, for example, when water is introduced into the body .

Despite the fact that blood represents the general internal environment of the body, the cells of organs and tissues do not directly come into contact with it. In multicellular organisms, each organ has its own internal environment (microenvironment) corresponding to its structural and functional features, and the normal state of organs depends on the chemical composition, physicochemical, biological and other properties of this microenvironment. Its homeostasis is determined by the functional state of histohematic barriers and their permeability in the directions of blood - tissue fluid; tissue fluid - blood.

Of particular importance is the constancy of the internal environment for the activity of the central nervous system: even minor chemical and physicochemical shifts that occur in the cerebrospinal fluid, glia, and pericellular spaces can cause a sharp disruption in the course of life processes in individual neurons or in their ensembles. A complex homeostatic system, including various neurohumoral, biochemical, hemodynamic and other regulatory mechanisms, is the system for ensuring the optimal level of blood pressure. At the same time, the upper limit of the level of arterial pressure is determined by the functionality of the baroreceptors of the vascular system of the body, and the lower limit is determined by the body's needs for blood supply.

The most perfect homeostatic mechanisms in the body of higher animals and humans include the processes of thermoregulation; in homoiothermic animals, fluctuations in temperature in the internal parts of the body during the most dramatic changes in temperature in the environment do not exceed tenths of a degree.

The organizing role of the nervous apparatus (the principle of nervism) underlies the well-known ideas about the essence of the principles of homeostasis. However, neither the dominant principle, nor the theory of barrier functions, nor the general adaptation syndrome, nor the theory of functional systems, nor the hypothalamic regulation of homeostasis, and many other theories can completely solve the problem of homeostasis.

In some cases, the concept of homeostasis is not quite rightly used to explain isolated physiological states, processes, and even social phenomena. This is how the terms “immunological”, “electrolyte”, “systemic”, “molecular”, “physico-chemical”, “genetic homeostasis”, etc., appear in the literature. Attempts have been made to reduce the problem of homeostasis to the principle of self-regulation. An example of solving the problem of homeostasis from the standpoint of cybernetics is Ashby's attempt (W.R. Ashby, 1948) to design a self-regulating device that simulates the ability of living organisms to maintain the level of certain quantities within physiologically acceptable limits.

In practice, researchers and clinicians face the issues of assessing the adaptive (adaptive) or compensatory capabilities of the body, their regulation, strengthening and mobilization, predicting the body's response to disturbing influences. Some states of vegetative instability, caused by insufficiency, excess or inadequacy of regulatory mechanisms, are considered as “diseases of homeostasis”. With a certain conventionality, they can include functional disturbances in the normal functioning of the body associated with its aging, forced restructuring of biological rhythms, some phenomena of vegetative dystonia, hyper- and hypocompensatory reactivity during stressful and extreme influences, etc.

To assess the state of homeostatic mechanisms in a physiological experiment and in clinical practice, various dosed functional tests are used (cold, thermal, adrenaline, insulin, mezaton, etc.) with the determination of the ratio of biologically active substances (hormones, mediators, metabolites) in blood and urine, etc. .d.

Biophysical mechanisms of homeostasis.

From the point of view of chemical biophysics, homeostasis is a state in which all processes responsible for energy transformations in the body are in dynamic equilibrium. This state is the most stable and corresponds to the physiological optimum. In accordance with the concepts of thermodynamics, an organism and a cell can exist and adapt to such environmental conditions under which a stationary flow of physicochemical processes can be established in a biological system, i.e. homeostasis. The main role in establishing homeostasis belongs primarily to cellular membrane systems, which are responsible for bioenergetic processes and regulate the rate of entry and release of substances by cells.

From these positions, the main causes of the disturbance are non-enzymatic reactions that are unusual for normal life activity, occurring in membranes; in most cases, these are chain reactions of oxidation involving free radicals that occur in cell phospholipids. These reactions lead to damage to the structural elements of cells and disruption of the regulatory function. Factors that cause homeostasis disorders also include agents that cause radical formation - ionizing radiation, infectious toxins, certain foods, nicotine, as well as a lack of vitamins, etc.

One of the main factors stabilizing the homeostatic state and functions of membranes are bioantioxidants, which inhibit the development of oxidative radical reactions.

Age features of homeostasis in children.

The constancy of the internal environment of the body and the relative stability of physicochemical parameters in childhood are provided with a pronounced predominance of anabolic metabolic processes over catabolic ones. This is an indispensable condition for growth and distinguishes the child's body from the body of adults, in which the intensity of metabolic processes is in a state of dynamic equilibrium. In this regard, the neuroendocrine regulation of the homeostasis of the child's body is more intense than in adults. Each age period is characterized by specific features of homeostasis mechanisms and their regulation. Therefore, in children much more often than in adults, there are severe violations of homeostasis, often life-threatening. These disorders are most often associated with the immaturity of the homeostatic functions of the kidneys, with disorders of the functions of the gastrointestinal tract or respiratory function of the lungs.

The growth of the child, expressed in an increase in the mass of his cells, is accompanied by distinct changes in the distribution of fluid in the body. The absolute increase in the volume of extracellular fluid lags behind the rate of overall weight gain, so the relative volume of the internal environment, expressed as a percentage of body weight, decreases with age. This dependence is especially pronounced in the first year after birth. In older children, the rate of change in the relative volume of extracellular fluid decreases. The system for regulating the constancy of the volume of liquid (volume regulation) provides compensation for deviations in the water balance within fairly narrow limits. A high degree of tissue hydration in newborns and young children determines a significantly higher need for water than in adults (per unit body weight). Losses of water or its limitation quickly lead to the development of dehydration due to the extracellular sector, i.e., the internal environment. At the same time, the kidneys - the main executive organs in the system of volume regulation - do not provide water savings. The limiting factor of regulation is the immaturity of the tubular system of the kidneys. The most important feature of the neuroendocrine control of homeostasis in newborns and young children is the relatively high secretion and renal excretion of aldosterone, which has a direct effect on the state of tissue hydration and the function of the renal tubules.

Regulation of the osmotic pressure of blood plasma and extracellular fluid in children is also limited. The osmolarity of the internal environment fluctuates over a wider range ( 50 mosm/l) , than adults

( 6 mosm/l) . This is due to the greater body surface area per 1 kg. weight and, consequently, with more significant losses of water during respiration, as well as with the immaturity of the renal mechanisms of urine concentration in children. Homeostasis disorders, manifested by hyperosmosis, are especially common in children during the neonatal period and the first months of life; at older ages, hypoosmosis begins to predominate, associated mainly with gastrointestinal or kidney disease. Less studied is the ionic regulation of homeostasis, which is closely related to the activity of the kidneys and the nature of nutrition.

It was previously believed that the main factor determining the value of the osmotic pressure of the extracellular fluid is the concentration of sodium, but more recent studies have shown that there is no close correlation between the sodium content in the blood plasma and the value of the total osmotic pressure in pathology. The exception is plasmatic hypertension. Therefore, homeostatic therapy by administering glucose-salt solutions requires monitoring not only the sodium content in serum or plasma, but also changes in the total osmolarity of the extracellular fluid. Of great importance in maintaining the total osmotic pressure in the internal environment is the concentration of sugar and urea. The content of these osmotically active substances and their effect on water-salt metabolism can increase sharply in many pathological conditions. Therefore, for any violations of homeostasis, it is necessary to determine the concentration of sugar and urea. In view of the foregoing, in children of early age, in violation of the water-salt and protein regimes, a state of latent hyper- or hypoosmosis, hyperazotemia may develop.

An important indicator characterizing homeostasis in children is the concentration of hydrogen ions in the blood and extracellular fluid. In the antenatal and early postnatal periods, the regulation of acid-base balance is closely related to the degree of blood oxygen saturation, which is explained by the relative predominance of anaerobic glycolysis in bioenergetic processes. Moreover, even moderate hypoxia in the fetus is accompanied by the accumulation of lactic acid in its tissues. In addition, the immaturity of the acidogenetic function of the kidneys creates the prerequisites for the development of "physiological" acidosis (a shift in the acid-base balance in the body towards a relative increase in the number of acid anions.). In connection with the peculiarities of homeostasis in newborns, disorders often occur that stand on the verge between physiological and pathological.

The restructuring of the neuroendocrine system during puberty (puberty) is also associated with changes in homeostasis. However, the functions of the executive organs (kidneys, lungs) reach their maximum degree of maturity at this age, so severe syndromes or homeostasis diseases are rare, but more often we are talking about compensated changes in metabolism, which can only be detected by a biochemical blood test. In the clinic, to characterize homeostasis in children, it is necessary to examine the following indicators: hematocrit, total osmotic pressure, sodium, potassium, sugar, bicarbonates and urea in the blood, as well as blood pH, p0 2 and pCO 2.

Features of homeostasis in the elderly and senile age.

The same level of homeostatic values in different age periods is maintained due to various shifts in the systems of their regulation. For example, the constancy of blood pressure at a young age is maintained due to a higher cardiac output and low total peripheral vascular resistance, and in the elderly and senile - due to a higher total peripheral resistance and a decrease in cardiac output. With the aging of the body, the constancy of the most important physiological functions is maintained in conditions of decreasing reliability and reducing the possible range of physiological changes in homeostasis. The preservation of relative homeostasis with significant structural, metabolic and functional changes is achieved by the fact that at the same time not only extinction, disturbance and degradation occurs, but also the development of specific adaptive mechanisms. Due to this, a constant level of sugar in the blood, blood pH, osmotic pressure, cell membrane potential, etc. is maintained.

Changes in the mechanisms of neurohumoral regulation, an increase in the sensitivity of tissues to the action of hormones and mediators against the background of a weakening of nervous influences, are essential in maintaining homeostasis during the aging process.

With the aging of the body, the work of the heart, pulmonary ventilation, gas exchange, renal functions, secretion of the digestive glands, the function of the endocrine glands, metabolism, etc., change significantly. These changes can be characterized as homeoresis - a regular trajectory (dynamics) of changes in the intensity of metabolism and physiological functions with age in time. The value of the course of age-related changes is very important for characterizing the aging process of a person, determining his biological age.

In the elderly and senile age, the general potential of adaptive mechanisms decreases. Therefore, in old age, with increased loads, stress and other situations, the likelihood of disruption of adaptive mechanisms and homeostasis disturbances increase. Such a decrease in the reliability of homeostasis mechanisms is one of the most important prerequisites for the development of pathological disorders in old age.

Thus, homeostasis is an integral concept, functionally and morphologically uniting cardiovascular system, respiratory system, renal system, water-electrolyte metabolism, acid-base balance.

Main purpose of cardio-vascular system – supply and distribution of blood in all pools of microcirculation. The amount of blood ejected by the heart in 1 minute is the minute volume. However, the function of the cardiovascular system is not just to maintain a given minute volume and its distribution among the pools, but to change the minute volume in accordance with the dynamics of tissue needs in different situations.

The main task of the blood is the transport of oxygen. Many surgical patients experience an acute drop in minute volume, which impairs oxygen delivery to tissues and can cause cell, organ, and even whole-body death. Therefore, the assessment of the function of the cardiovascular system should take into account not only the minute volume, but also the supply of oxygen to the tissues and their need for it.

Main purpose respiratory system - ensuring adequate gas exchange between the body and the environment at a constantly changing rate of metabolic processes. The normal function of the respiratory system is to maintain a constant level of oxygen and carbon dioxide in the arterial blood with normal vascular resistance in the pulmonary circulation and with the usual expenditure of energy for respiratory work.

This system is closely connected with other systems, and primarily with the cardiovascular system. The function of the respiratory system includes ventilation, pulmonary circulation, diffusion of gases across the alveolar-capillary membrane, transport of gases by the blood, and tissue respiration.

Functions renal system : The kidneys are the main organ designed to maintain the constancy of the physicochemical conditions in the body. The main of their functions is excretory. It includes: regulation of water and electrolyte balance, maintenance of acid-base balance and removal of metabolic products of proteins and fats from the body.

Functions water and electrolyte metabolism : water in the body plays a transport role, filling cells, interstitial (intermediate) and vascular spaces, is a solvent of salts, colloids and crystalloids and takes part in biochemical reactions. All biochemical fluids are electrolytes, since salts and colloids dissolved in water are in a dissociated state. It is impossible to list all the functions of electrolytes, but the main ones are: maintaining osmotic pressure, maintaining the reaction of the internal environment, participating in biochemical reactions.

Main purpose acid-base balance It consists in maintaining the constancy of the pH of the liquid media of the body as the basis for normal biochemical reactions and, consequently, life. Metabolism occurs with the indispensable participation of enzymatic systems, the activity of which closely depends on the chemical reaction of the electrolyte. Together with water-electrolyte metabolism, acid-base balance plays a decisive role in the ordering of biochemical reactions. Buffer systems and many physiological systems of the body take part in the regulation of acid-base balance.

homeostasis

The most important biological constants. Among the most important biological constants, for the maintenance of which at a relatively unchanged level, various physiological systems of the body are responsible, we should mention body temperature, blood glucose level, content of H+ ions in body fluids, partial tension of oxygen and carbon dioxide in tissues.

Homeostasis is:

homeostasis

homeostasis(ancient Greek ὁμοιοστάσις from ὁμοιος - the same, similar and στάσις - standing, immobility) - self-regulation, the ability of an open system to maintain the constancy of its internal state through coordinated reactions aimed at maintaining dynamic balance. The desire of the system to reproduce itself, to restore the lost balance, to overcome the resistance of the external environment.

Population homeostasis is the ability of a population to maintain a certain number of its individuals for a long time.

The American physiologist Walter B. Cannon proposed the term in 1932 in his book The Wisdom of the Body as a name for "the coordinated physiological processes that maintain the body's most stable states." Later, this term was extended to the ability to dynamically maintain the constancy of its internal state of any open system. However, the concept of the constancy of the internal environment was formulated as early as 1878 by the French scientist Claude Bernard.

General information

The term "homeostasis" is most often used in biology. For multicellular organisms to exist, it is necessary to maintain the constancy of the internal environment. Many ecologists are convinced that this principle also applies to the external environment. If the system is unable to restore its balance, it may eventually cease to function.

Complex systems - for example, the human body - must have homeostasis in order to maintain stability and exist. These systems not only have to strive to survive, they also have to adapt to environmental changes and evolve.

properties of homeostasis

Homeostatic systems have the following properties:

instability system: tests how it can best adapt.
Striving for balance: all the internal, structural and functional organization of systems contributes to maintaining balance.
unpredictability: The resultant effect of a certain action can often be different from what was expected.

Examples of homeostasis in mammals:

Regulation of the amount of micronutrients and water in the body - osmoregulation. Carried out in the kidneys.
Removal of waste products of the metabolic process - isolation. It is carried out by exocrine organs - kidneys, lungs, sweat glands and the gastrointestinal tract.
Body temperature regulation. Lowering the temperature through sweating, a variety of thermoregulatory reactions.
Regulation of blood glucose levels. It is mainly carried out by the liver, insulin and glucagon secreted by the pancreas.

It is important to note that although the body is in balance, its physiological state can be dynamic. Many organisms exhibit endogenous changes in the form of circadian, ultradian, and infradian rhythms. So, even while in homeostasis, body temperature, blood pressure, heart rate and most metabolic indicators are not always at a constant level, but change over time.

Mechanisms of homeostasis: feedback

Main article: Feedback

When there is a change in variables, there are two main types of feedback that the system responds to:

Negative feedback, expressed as a reaction in which the system responds in such a way as to reverse the direction of change. Since the feedback serves to maintain the constancy of the system, it allows you to maintain homeostasis.
- For example, when the concentration of carbon dioxide in the human body increases, the lungs are signaled to increase their activity and exhale more carbon dioxide.
- Thermoregulation is another example of negative feedback. When body temperature rises (or falls), thermoreceptors in the skin and hypothalamus register the change, triggering a signal from the brain. This signal, in turn, causes a response - a decrease in temperature (or increase).
Positive feedback, which is expressed as an increase in the change in a variable. It has a destabilizing effect, so it does not lead to homeostasis. Positive feedback is less common in natural systems, but also has its uses.
- For example, in nerves, a threshold electrical potential causes the generation of a much larger action potential. Blood clotting and birth events are other examples of positive feedback.

Stable systems need combinations of both types of feedback. While negative feedback allows you to return to a homeostatic state, positive feedback is used to move to a completely new (and quite possibly less desirable) state of homeostasis, a situation called "metastability". Such catastrophic changes can occur, for example, with an increase in nutrients in rivers with clear water, which leads to a homeostatic state of high eutrophication (algae overgrowth of the channel) and turbidity.

Ecological homeostasis

Ecological homeostasis is observed in climax communities with the highest possible biodiversity under favorable environmental conditions.

In disturbed ecosystems, or sub-climax biological communities - such as the island of Krakatoa, after a strong volcanic eruption in 1883 - the state of homeostasis of the previous forest climax ecosystem was destroyed, like all life on this island. Krakatoa went through a chain of ecological changes in the years following the eruption, in which new plant and animal species succeeded each other, which led to biodiversity and, as a result, a climax community. Ecological succession in Krakatoa took place in several stages. A complete chain of successions leading to a climax is called a preserie. In the Krakatoa example, this island developed a climax community with 8,000 different species recorded in 1983, a hundred years after the eruption wiped out life on it. The data confirm that the position is maintained in homeostasis for some time, while the emergence of new species very quickly leads to the rapid disappearance of old ones.

The case of Krakatoa and other disturbed or intact ecosystems shows that the initial colonization by pioneer species occurs through positive feedback reproduction strategies in which the species disperse, producing as many offspring as possible, but with little or no investment in the success of each individual. . In such species, there is a rapid development and an equally rapid collapse (for example, through an epidemic). As an ecosystem approaches climax, such species are replaced by more complex climax species that adapt through negative feedback to the specific conditions of their environment. These species are carefully controlled by the potential capacity of the ecosystem and follow a different strategy - the production of smaller offspring, in the reproductive success of which in the microenvironment of its specific ecological niche, more energy is invested.

Development begins with the pioneer community and ends with the climax community. This climax community is formed when flora and fauna come into balance with the local environment.

Such ecosystems form heterarchies in which homeostasis at one level contributes to homeostatic processes at another complex level. For example, the loss of leaves on a mature tropical tree makes room for new growth and enriches the soil. Equally, the tropical tree reduces the access of light to lower levels and helps prevent other species from invading. But the trees also fall to the ground and the development of the forest depends on the constant change of trees, the cycle of nutrients carried out by bacteria, insects, fungi. Similarly, such forests contribute to ecological processes, such as the regulation of microclimates or ecosystem hydrological cycles, and several different ecosystems may interact to maintain river drainage homeostasis within a biological region. The variability of bioregions also plays a role in the homeostatic stability of a biological region, or biome.

Biological homeostasis

Further information: Acid-base balance

Homeostasis acts as a fundamental characteristic of living organisms and is understood as maintaining the internal environment within acceptable limits.

The internal environment of the body includes body fluids - blood plasma, lymph, intercellular substance and cerebrospinal fluid. Maintaining the stability of these fluids is vital for organisms, while its absence leads to damage to the genetic material.

With regard to any parameter, organisms are divided into conformational and regulatory. Regulatory organisms keep the parameter at a constant level, regardless of what happens in the environment. Conformational organisms allow the environment to determine the parameter. For example, warm-blooded animals maintain a constant body temperature, while cold-blooded animals exhibit a wide temperature range.

We are not talking about the fact that conformational organisms do not have behavioral adaptations that allow them to regulate the given parameter to some extent. Reptiles, for example, often sit on heated rocks in the morning to raise their body temperature.

The advantage of homeostatic regulation is that it allows the body to function more efficiently. For example, cold-blooded animals tend to become lethargic in cold temperatures, while warm-blooded animals are almost as active as ever. On the other hand, regulation requires energy. The reason why some snakes can only eat once a week is that they use much less energy to maintain homeostasis than mammals.

Cellular homeostasis

Homeostasis in the human body

Further information: Acid-base balance See also: Blood buffer systems

Various factors affect the ability of body fluids to sustain life. These include parameters such as temperature, salinity, acidity, and the concentration of nutrients - glucose, various ions, oxygen, and waste products - carbon dioxide and urine. Since these parameters affect the chemical reactions that keep the body alive, there are built-in physiological mechanisms to keep them at the required level.

Homeostasis cannot be considered the cause of the processes of these unconscious adaptations. It should be taken as a general characteristic of many normal processes acting together, and not as their root cause. Moreover, there are many biological phenomena that do not fit this model - for example, anabolism.

Other areas

The concept of "homeostasis" is also used in other areas.

The actuary can talk about risk homeostasis, in which, for example, people who have non-stick brakes on their cars are not in a safer position than those who do not, because these people unconsciously compensate for the safer car by risky driving. This happens because some of the holding mechanisms - such as fear - stop working.

Sociologists and psychologists can talk about stress homeostasis- the desire of a population or individual to remain at a certain stress level, often artificially causing stress if the "natural" level of stress is not enough.

Examples

thermoregulation
- Skeletal muscle trembling may begin if the body temperature is too low.
- Another type of thermogenesis involves the breakdown of fats to release heat.
- Sweating cools the body through evaporation.
Chemical regulation
- The pancreas secretes insulin and glucagon to control blood glucose levels.
- The lungs take in oxygen and release carbon dioxide.
- The kidneys excrete urine and regulate the level of water and a number of ions in the body.

Many of these organs are controlled by hormones from the hypothalamic-pituitary system.

Homeostasis from a biological and ecological point of view

In homeostasis apply to any multicellular organisms. At the same time, ecologists often pay attention to the balance of the external environment. It is believed that this is the homeostasis of the ecosystem, which is also subject to change and is constantly rebuilt for further existence.

If the balance in any system is disturbed and it is not able to restore it, then this leads to a complete cessation of functioning.

Man is no exception, homeostatic mechanisms play an important role in daily life, and the permissible degree of change in the main indicators of the human body is very small. With unusual fluctuations in the external or internal environment, a malfunction in homeostasis can lead to fatal consequences.

What is homeostasis and its types

Every day a person is exposed to various environmental factors, but in order for the basic biological processes in the body to continue to work stably, their conditions must not change. It is in maintaining this stability that the main role of homeostasis lies.

It is customary to distinguish three main types:

Genetic.
Physiological.
Structural (regenerative or cellular).

For a full-fledged existence, a person needs the work of all three types of homeostasis in a complex, if one of them fails, this leads to unpleasant consequences for health. Well-coordinated work of processes will allow you to ignore or endure the most common changes with minimal inconvenience and feel confident.

This type of homeostasis is the ability to maintain a single genotype within one population. At the molecular-cellular level, a single genetic system is maintained, which carries a certain set of hereditary information.

The mechanism allows individuals to interbreed, while maintaining the balance and uniformity of a conditionally closed group of people (population).

Physiological homeostasis

This type of homeostasis is responsible for maintaining the main vital signs in an optimal state:

body temperature.
Blood pressure.
Digestive stability.

The immune, endocrine and nervous systems are responsible for its proper functioning. In the event of an unforeseen failure in the operation of one of the systems, this immediately affects the well-being of the whole organism, leads to a weakening of protective functions and the development of diseases.

Cellular homeostasis (structural)

This species is also called "regeneration", which probably best describes the functional features.

The main forces of such homeostasis are aimed at restoring and healing damaged cells of the internal organs of the human body. It is these mechanisms that, when working properly, allow the body to recover from illness or injury.

The main mechanisms of homeostasis develop and evolve together with a person, better adapting to changes in the external environment.

Functions of homeostasis

In order to correctly understand the functions and properties of homeostasis, it is best to consider its action on specific examples.

So, for example, when playing sports, human breathing and pulse quicken, which indicates the body's desire to maintain internal balance under changed environmental conditions.

When moving to a country with a climate that is significantly different from the usual, for some time you can feel unwell. Depending on the general health of a person, the mechanisms of homeostasis allow you to adapt to new living conditions. For some, acclimatization is not felt and the internal balance quickly adjusts, while others have to wait a little before the body adjusts its performance.

In conditions of elevated temperature, a person becomes hot and sweating begins. This phenomenon is considered direct evidence of the functioning of self-regulation mechanisms.

In many ways, the work of the main homeostatic functions depends on heredity, the genetic material transmitted from the older generation of the family.

Based on the examples given, it is clearly possible to trace the main functions:

Energy.
Adaptive.
Reproductive.

It is important to pay attention to the fact that in old age, as well as in infancy, the stable work of homeostasis requires special attention, due to the fact that the reaction of the main regulatory systems during these periods of life is slow.

properties of homeostasis

Knowing about the basic functions of self-regulation, it is also useful to understand what properties it has. Homeostasis is a complex interrelation of processes and reactions. Among the properties of homeostasis are:

Instability.
Striving for balance.
Unpredictability.

Mechanisms are in constant change, testing conditions in order to choose the best option for adapting to them. This is the property of instability.

Balance is the main goal and property of any organism, it constantly strives for it, both structurally and functionally.

In some cases, the reaction of the body to changes in the external or internal environment can become unexpected, lead to restructuring of vital systems. The unpredictability of homeostasis can cause some discomfort, which does not indicate a further detrimental effect on the state of the body.

How to improve the functioning of the mechanisms of the homeostatic system

From the point of view of medicine, any disease is evidence of a malfunction in homeostasis. External and internal threats constantly affect the body, and only coherence in the work of the main systems will help to cope with them.

The weakening of the immune system does not happen for no reason. Modern medicine has a wide range of tools that can help a person maintain their health, regardless of what caused the failure.

Changing weather conditions, stressful situations, injuries - all this can lead to the development of diseases of varying severity.

In order for the functions of homeostasis to work correctly and as quickly as possible, it is necessary to monitor the general state of your health. To do this, you can consult a doctor for an examination to determine your vulnerabilities and choose a set of therapy to eliminate them. Regular diagnostics will help to better control the basic processes of life.

In this case, it is important to independently follow simple recommendations:

Avoid stressful situations to protect the nervous system from constant overexertion.
Keep track of your diet, do not overload yourself with heavy foods, avoid mindless starvation, which will allow the digestive system to more easily cope with its work.
Choose suitable vitamin complexes to reduce the impact of seasonal weather changes.

A vigilant attitude towards one's own health will help the homeostatic processes to respond in a timely and correct manner to any changes.