Homeostasis and its meaning. Homeostasis its biological significance

The body of higher animals has developed adaptations that counteract many influences of the external environment, providing relatively constant conditions for the existence of cells. This is of utmost importance for the functioning of the whole organism. We illustrate this with examples. The cells of the body of warm-blooded animals, i.e. animals with a constant body temperature, function normally only within narrow temperature limits (in humans, within 36-38°). A temperature shift beyond these boundaries leads to disruption of cell activity. At the same time, the body of warm-blooded animals can normally exist with much wider fluctuations in external temperature. For example, a polar bear can live at temperatures of -70° and +20-30°. This is due to the fact that in the whole organism its heat exchange with the environment is regulated, i.e. heat generation (intensity of chemical processes occurring with the release of heat) and heat transfer. Thus, at low ambient temperatures, heat generation increases and heat transfer decreases. Therefore, when the external temperature fluctuates (within certain limits), the body temperature remains constant.

The functions of the body's cells are normal only when the osmotic pressure is relatively constant, due to the constant content of electrolytes and water in the cells. Changes in osmotic pressure - its decrease or its increase - lead to sudden disturbances in the functions and structure of cells. The organism as a whole can exist for some time even with an excess supply and deprivation of water, and with large and small amounts of salts in food. This is explained by the presence in the body of devices that help maintain
constancy of the amount of water and electrolytes in the body. In case of excess water intake, significant amounts of it are quickly excreted from the body by the excretory organs (kidneys, sweat glands, skin), and if there is a lack of water, it is retained in the body. Likewise, the excretory organs regulate the content of electrolytes in the body: they quickly remove excess amounts or retain them in body fluids when there is insufficient salt intake.

The concentration of individual electrolytes in the blood and tissue fluid, on the one hand, and in the protoplasm of cells, on the other, is different. The blood and tissue fluid contain more sodium ions, and the protoplasm of cells contains more potassium ions. The difference in ion concentrations inside and outside the cell is achieved by a special mechanism that retains potassium ions inside the cell and does not allow sodium ions to accumulate in the cell. This mechanism, the nature of which is not yet clear, is called the sodium-potassium pump and is associated with the process of cell metabolism.

Body cells are very sensitive to shifts in the concentration of hydrogen ions. A change in the concentration of these ions in one direction or another sharply disrupts the vital activity of cells. The internal environment of the body is characterized by a constant concentration of hydrogen ions, depending on the presence of so-called buffer systems in the blood and tissue fluid (p. 48) and on the activity of the excretory organs. When the content of acids or alkalis in the blood increases, they are quickly eliminated from the body and in this way the constancy of the concentration of hydrogen ions in the internal environment is maintained.

Cells, especially nerve cells, are very sensitive to changes in blood sugar levels, which serve as an important nutrient. Therefore, the constancy of blood sugar levels is of great importance for the life process. It is achieved by the fact that when the blood sugar level increases in the liver and muscles, the polysaccharide deposited in the cells, glycogen, is synthesized from it, and when the blood sugar level decreases, glycogen is broken down in the liver and muscles and grape sugar is released into the blood.

The constancy of the chemical composition and physicochemical properties of the internal environment is an important feature of the organisms of higher animals. To denote this constancy, W. Cannon proposed a term that has become widespread - homeostasis. The expression of homeostasis is the presence of a number of biological constants, i.e., stable quantitative indicators that characterize the normal state of the body. Such constant indicators are: body temperature, osmotic pressure of blood and tissue fluid, the content of sodium, potassium, calcium, chlorine and phosphorus ions, as well as proteins and sugar, the concentration of hydrogen ions and a number of others.

Noting the constancy of the composition, physicochemical and biological properties of the internal environment, it should be emphasized that it is not absolute, but relative and dynamic. This constancy is achieved by the continuously performed work of a number of organs and tissues, as a result of which the shifts in the composition and physico-chemical properties of the internal environment that occur under the influence of changes in the external environment and as a result of the vital activity of the body are leveled out.

The role of different organs and their systems in maintaining homeostasis is different. Thus, the digestive system ensures that nutrients enter the bloodstream in the form in which they can be used by the cells of the body. The circulatory system carries out the continuous movement of blood and transport of various substances in the body, as a result of which nutrients, oxygen and various chemical compounds formed in the body itself are supplied to the cells, and breakdown products, including carbon dioxide, released by the cells are transferred to the organs , which remove them from the body. The respiratory organs ensure the supply of oxygen to the blood and the removal of carbon dioxide from the body. The liver and a number of other organs carry out a significant number of chemical transformations - the synthesis and breakdown of many chemical compounds that are important in the life of cells. The excretory organs - kidneys, lungs, sweat glands, skin - remove the end products of the breakdown of organic substances from the body and maintain a constant content of water and electrolytes in the blood, and therefore in the tissue fluid and cells of the body.

The nervous system plays a critical role in maintaining homeostasis. Sensitively reacting to various changes in the external or internal environment, it regulates the activity of organs and systems in such a way that shifts and disturbances that occur or could occur in the body are prevented and leveled out.

Thanks to the development of devices that ensure the relative constancy of the internal environment of the body, its cells are less susceptible to the changing influences of the external environment. According to Cl. Bernard, “constancy of the internal environment is a condition for free and independent life.”

Homeostasis has certain boundaries. When an organism stays, especially for a long time, in conditions that differ significantly from those to which it is adapted, homeostasis is disrupted and changes may occur that are incompatible with normal life. Thus, with a significant change in external temperature in the direction of either increasing or decreasing, body temperature may increase or decrease and overheating or cooling of the body may occur, leading to death. Likewise, with a significant restriction of the intake of water and salts into the body or a complete deprivation of these substances, the relative constancy of the composition and physicochemical properties of the internal environment is disrupted after some time and life ceases.

A high level of homeostasis occurs only at certain stages of species and individual development. Lower animals do not have sufficiently developed adaptations to mitigate or eliminate the effects of changes in the external environment. For example, relative constancy of body temperature (homeothermy) is maintained only in warm-blooded animals. In so-called cold-blooded animals, body temperature is close to the temperature of the external environment and is variable (poikilothermia). A newborn animal does not have the same constancy of body temperature, composition and properties of the internal environment as an adult organism.

Even small disturbances of homeostasis lead to pathology, and therefore the determination of relatively constant physiological indicators, such as body temperature, blood pressure, composition, physicochemical and biological properties of blood, etc., is of great diagnostic importance.

Among the properties inherent in living beings, homeostasis is mentioned. This concept refers to the relative constancy characteristic of an organism. It is worth understanding in detail why homeostasis is needed, what it is, and how it manifests itself.

Homeostasis is a property of a living organism that allows it to maintain important characteristics within acceptable limits. For normal functioning, constancy of the internal environment and individual indicators is necessary.

External influences and unfavorable factors lead to changes, which negatively affect the general condition. But the body is able to recover on its own, returning its characteristics to optimal levels. This happens due to the property in question.

Considering the concept of homeostasis and finding out what it is, it is necessary to determine how this property is realized. The easiest way to understand this is to use cells as an example. Each is a system characterized by mobility. Under the influence of certain circumstances, its features may change.

For normal functioning, a cell must have those properties that are optimal for its existence. If indicators deviate from the norm, vitality decreases. To prevent death, all properties must be returned to their original state.

This is what homeostasis is all about. It neutralizes any changes that occur as a result of the effect on the cell.

Definition

Let us define what this property of a living organism is. Initially, this term was used to describe the ability to maintain a constant internal environment. Scientists assumed that this process affects only the intercellular fluid, blood and lymph.

It is their constancy that allows the body to maintain a stable state. But later it was discovered that such an ability is inherent in any open system.

The definition of homeostasis has changed. Now this is the name for self-regulation of an open system, which consists of maintaining dynamic equilibrium through the implementation of coordinated reactions. Thanks to them, the system maintains relatively constant parameters necessary for normal life.

This term began to be used not only in biology. It has found application in sociology, psychology, medicine and other sciences. Each of them has its own interpretation of this concept, but they have a common essence - constancy.

Characteristics

To understand what exactly is called homeostasis, you need to find out what the characteristics of this process are.

The phenomenon has such features as:

1. Striving for balance. All parameters of an open system must be in accordance with each other.
2. Identifying opportunities for adaptation. Before the parameters are changed, the system must determine whether it is possible to adapt to the changed living conditions. This happens through analysis.
3. Unpredictability of results. Regulation of indicators does not always lead to positive changes.

The phenomenon under consideration is a complex process, the implementation of which depends on various circumstances. Its occurrence is determined by the properties of an open system and the peculiarities of its operating conditions.

Application in biology

This term is used not only in relation to living beings. It is used in various fields. To better understand what homeostasis is, you need to find out what meaning biologists put into it, since this is the area in which it is used most often.

This science attributes this property to all creatures without exception, regardless of their structure. It is characteristically unicellular and multicellular. In unicellular organisms it manifests itself in maintaining a constant internal environment.

In organisms with a more complex structure, this feature concerns individual cells, tissues, organs and systems. Among the parameters that must be constant are body temperature, blood composition, and enzyme content.

In biology, homeostasis is not only the preservation of constancy, but also the ability of the body to adapt to changing environmental conditions.

Biologists distinguish two types of creatures:

1. Conformational, in which organismal characteristics are preserved, regardless of conditions. These include warm-blooded animals.
2. Regulatory, responding to changes in the external environment and adapting to them. These include amphibians.

If there are violations in this area, recovery or adaptation is not observed. The body becomes vulnerable and may die.

How does it happen in humans?

The human body consists of a large number of cells that are interconnected and form tissues, organs, and organ systems. Due to external influences, changes can occur in each system and organ, which entail changes in the entire body.

But for normal functioning, the body must maintain optimal features. Accordingly, after any impact it needs to return to its original state. This happens due to homeostasis.

This property affects parameters such as:

• temperature,
• nutrient content
• acidity,
• blood composition,
• waste removal.

All these parameters affect the condition of the person as a whole. The normal course of chemical reactions that contribute to the preservation of life depends on them. Homeostasis allows you to restore previous indicators after any impact, but is not the cause of adaptive reactions. This property is a general characteristic of a large number of processes operating simultaneously.

For blood

Blood homeostasis is one of the main characteristics affecting the viability of a living being. Blood is its liquid basis, since it is found in every tissue and every organ.

Thanks to it, individual parts of the body are supplied with oxygen, and harmful substances and metabolic products are removed.

If there are disturbances in the blood, then the performance of these processes deteriorates, which affects the functioning of organs and systems. All other functions depend on the constancy of its composition.

This substance must maintain the following parameters relatively constant:

• acidity level;
• osmotic pressure;
• plasma electrolyte ratio;
• amount of glucose;
• cellular composition.

Due to the ability to maintain these indicators within normal limits, they do not change even under the influence of pathological processes. Minor fluctuations are inherent in them, and this does not harm. But they rarely exceed normal values.

This is interesting! If disturbances occur in this area, the blood parameters do not return to their original position. This indicates the presence of serious problems. The body becomes unable to maintain balance. As a result, there is a risk of complications.

Use in medicine

This concept is widely used in medicine. In this area, its essence is almost similar to its biological meaning. This term in medical science covers compensatory processes and the body's ability to self-regulate.

This concept includes the relationships and interactions of all components involved in the implementation of the regulatory function. It covers metabolic processes, breathing, and blood circulation.

The difference between the medical term is that science considers homeostasis as an auxiliary factor in treatment. In diseases, body functions are disrupted due to damage to organs. This affects the entire body. It is possible to restore the activity of the problem organ with the help of therapy. The ability in question contributes to increasing its effectiveness. Thanks to the procedures, the body itself directs efforts to eliminate pathological phenomena, trying to restore normal parameters.

In the absence of opportunities for this, an adaptation mechanism is activated, which manifests itself in reducing the load on the damaged organ. This allows you to reduce damage and prevent active progression of the disease. We can say that such a concept as homeostasis in medicine is considered from a practical point of view.

Wikipedia

The meaning of any term or characteristic of any phenomenon is most often learned from Wikipedia. She examines this concept in some detail, but in the simplest sense: she calls it the body’s desire for adaptation, development and survival.

This approach is explained by the fact that in the absence of this property, it will be difficult for a living creature to adapt to changing environmental conditions and develop in the right direction.

And if disturbances occur in the functioning, the creature will simply die, since it will not be able to return to its normal state.

Important! In order for the process to be carried out, it is necessary that all organs and systems work harmoniously. This will ensure that all vital parameters remain within normal limits. If a particular indicator cannot be regulated, this indicates problems with the implementation of this process.

Examples

Examples of this phenomenon will help you understand what homeostasis is in the body. One of them is maintaining a constant body temperature. Some changes are inherent in it, but they are minor. A serious increase in temperature is observed only in the presence of diseases. Another example is blood pressure readings. A significant increase or decrease in indicators occurs due to health problems. At the same time, the body strives to return to normal characteristics.

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Let's sum it up

The property being studied is one of the key ones for normal functioning and preservation of life; it is the ability to restore optimal indicators of vital parameters. Changes in them can occur under the influence of external influences or pathologies. Thanks to this ability, living beings can resist external factors.

HOMEOSTASIS, homeostasis (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 the basic physiological functions (circulation, respiration, thermoregulation, metabolism, etc.) human and animal bodies. Regulatory mechanisms supporting physiol. the state or properties of cells, organs and systems of the whole organism at an optimal level are called homeostatic.

As is known, 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 external and 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 whose cellular elements 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 regulating intra- and intercellular relationships have, in some cases, mutually opposite (antagonistic) effects that balance each other. This leads to the establishment of a mobile physiol, background (fiziol, balance) in the body and allows the living system to maintain relative dynamic constancy, despite changes in the environment and shifts that arise during the life of the organism.

The term “homeostasis” was proposed in 1929 by Amer. physiologist W. Cannon, who believed that physiol, the processes that maintain stability in the body are so complex and diverse that it is advisable to unite them under the general name G. However, back in 1878, C. Bernard wrote that all life processes have only one the goal is to maintain constant living conditions in our internal environment. Similar statements are found in the works of many researchers of the 19th and first half of the 20th centuries. [E. Pfluger, S. Richet, Frederic (L. A. Fredericq), I. M. Sechenov, I. P. Pavlov, K. M. Bykov, etc.]. The works of L. S. Stern (o.), devoted to the role of barrier functions (see) regulating the composition and properties of the microenvironment of organs and tissues, were of great importance for the study of the problem of G.

The very idea of ​​G. does not correspond to the concept of stable (non-fluctuating) equilibrium in the body - the principle of equilibrium is not applicable to complex physiol, and biochemical. processes occurring in living systems. It is also incorrect to contrast G. with rhythmic fluctuations in the internal environment (see Biological rhythms). G. in a broad sense, covers issues of the cyclic and phase course of reactions, compensation (see Compensatory processes), regulation and self-regulation of physiology, functions (see Self-regulation of physiological functions), the dynamics of the interdependence of nervous, humoral and other components of the regulatory process. G.'s boundaries can be rigid and flexible, and vary depending on individual age, gender, social, and profession. and other conditions.

Of particular importance for the life of the body is the constancy of the composition of the blood - the fluid matrix of the body, as W. Cannon puts it. 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. So, for example, blood pH, as a rule, does not goes beyond 7.35-7.47. Even severe disorders of acid-base metabolism with patol, the accumulation of acids in tissue fluid, for example, with diabetic acidosis, have very little effect on the active reaction of the blood (see Acid-base balance). 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 patol conditions (see Osmotic pressure). Maintaining a constant osmotic pressure is of paramount importance for water metabolism and maintaining ionic balance in the body (see Water-salt metabolism). The concentration of sodium ions in the internal environment is the most constant. The content of other electrolytes also varies within narrow limits. The presence of a large number of osmoreceptors (see) in tissues and organs, including in the central nervous formations (hypothalamus, hippocampus), and a coordinated system of regulators of water metabolism and ion composition allows the body to quickly eliminate shifts in the osmotic pressure of the blood that occur, for example ., when introducing water 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 characteristics, and the normal state of the organs depends on the chemical. composition, physical-chemical, biol, and other properties of this microenvironment. Its G. is determined by the functional state of histohematic barriers (see Barrier functions) and their permeability in the directions blood -> tissue fluid, tissue fluid -> blood.

The constancy of the internal environment for the activity of the center is of particular importance. n. pp.: even minor chemicals. and physical-chemical shifts that occur in the cerebrospinal fluid, glia and pericellular spaces can cause a sharp disruption in the course of vital processes in individual neurons or in their ensembles (see Blood-brain barrier). A complex homeostatic system, including various neurohumoral, biochemical, hemodynamic and other regulatory mechanisms, is the system for ensuring the optimal level of blood pressure (see). In this case, the upper limit of the blood pressure level is determined by the functionality of the baroreceptors of the body’s vascular system (see Angioceptors), and the lower limit is determined by the body’s blood supply needs.

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

Different researchers explain the mechanisms of general biology in different ways. character underlying G. Thus, W. Cannon attached particular importance to c. n. pp., L.A. Orbeli considered the adaptive-trophic function of the sympathetic nervous system to be one of the leading factors. The organizing role of the nervous apparatus (the principle of nervism) underlies widely known ideas about the essence of the principles of G. (I. M. Sechenov, I. P. Pavlov, A. D. Speransky, etc.). However, neither the dominant principle (A. A. Ukhtomsky), nor the theory of barrier functions (L. S. Stern), nor the general adaptation syndrome (G. Selye), nor the theory of functional systems (P. K. Anokhin), nor the hypothalamic regulation of G (N.I. Grashchenkov) and many other theories do not completely solve the problem of G.

In some cases, the idea of ​​G. is not entirely legitimately used to explain isolated physiol, conditions, processes and even social phenomena. This is how the terms “immunological”, “electrolyte”, “systemic”, “molecular”, “physico-chemical”, “genetic homeostasis”, etc., found in the literature, arose. Attempts were made to reduce the problem of G. to the principle of self-regulation (see Biological system, autoregulation in biological systems). An example of a solution to the problem of G. from the perspective of cybernetics is Ashby’s attempt (W. R. Ashby, 1948) to construct a self-regulating device that models the ability of living organisms to maintain the level of certain quantities within physiol, acceptable limits (see Homeostat). Some authors consider the internal environment of the body in the form of a complex chain system with many “active inputs” (internal organs) and individual physiol indicators (blood flow, blood pressure, gas exchange, etc.), the value of each of which is determined by the activity of the “inputs”.

In practice, researchers and clinicians are faced with questions of assessing the adaptive (adaptive) or compensatory capabilities of the body, their regulation, strengthening and mobilization, and predicting the body's responses to disturbing influences. Some states of vegetative instability, caused by insufficiency, excess or inadequacy of regulatory mechanisms, are considered “diseases of homeostasis”. With a certain convention, these may 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 under stressful and extreme influences (see Stress), etc.

To assess the state of homeostatic mechanisms in physiol, experiment and in wedge, practice, a variety of dosed functional tests are used (cold, heat, adrenaline, insulin, mesaton, etc.) with determination of the ratio of biologically active substances (hormones, mediators, metabolites) in the blood and urine. etc.

Biophysical mechanisms of homeostasis

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

From this point of view, the main causes of the disorder are non-enzymatic reactions that occur in membranes, unusual for normal life; in most cases, these are oxidation chain reactions involving free radicals that occur in cell phospholipids. These reactions lead to damage to the structural elements of cells and disruption of regulatory function (see Radicals, Chain reactions). Factors that cause G. 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 that stabilize the homeostatic state and functions of membranes are bioantioxidants, which inhibit the development of oxidative radical reactions (see Antioxidants).

Age-related features of homeostasis in children

The constancy of the internal environment of the body and the relative stability of physical-chemical. indicators in childhood are ensured with a pronounced predominance of anabolic metabolic processes over catabolic ones. This is an indispensable condition for growth (see) and distinguishes the child’s body from the body of adults, in whom the intensity of metabolic processes is in a state of dynamic equilibrium. In this regard, the neuroendocrine regulation of the child’s body turns out to be more intense than in adults. Each age period is characterized by specific features of G.’s mechanisms and their regulation. Therefore, severe gastrointestinal disorders, often life-threatening, occur in children much more often than in adults. 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. tract or respiratory function of the lungs (see Breathing).

The growth of a child, expressed in an increase in the mass of its cells, is accompanied by distinct changes in the distribution of fluid in the body (see Water-salt metabolism). 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 fluid volume (volume regulation) provides compensation for deviations in water balance within fairly narrow limits. The high degree of tissue hydration in newborns and young children determines the child’s need for water (per unit body weight) is significantly higher than in adults. Loss of water or its limitation quickly leads 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 volumoregulation system - do not provide water savings. The limiting factor of regulation is the immaturity of the renal tubular system. The most important feature of neuroendocrine control of G. in newborns and young children is the relatively high secretion and renal excretion of aldosterone (see), which has a direct effect on the state of tissue hydration and the function of the renal tubules.

Regulation of 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 in adults (+ 6 mOsm/L). This is due to the larger body surface area per 1 kg of weight and, therefore, to more significant water losses during respiration, as well as the immaturity of the renal mechanisms of urine concentration in children. G.'s 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 with ch. arr. with yellow-kish. kidney disease or disease. Less studied is the ionic regulation of blood, which is closely related to the activity of the kidneys and the nature of nutrition.

Previously, it was believed that the main factor determining the osmotic pressure of the extracellular fluid was the sodium concentration, 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. Consequently, carrying out homeostatic therapy by administering glucose-salt solutions requires monitoring not only the sodium content in the serum or blood plasma, but also changes in the total osmolarity of the extracellular fluid. The concentration of sugar and urea is of great importance in maintaining the general osmotic pressure in the internal environment. The content of these osmotically active substances and their effect on water-salt metabolism in many pathol states can increase sharply. Therefore, for any G. violations, it is necessary to determine the concentration of sugar and urea. Due to the above, in young children, if the water-salt and protein regimes are disturbed, a state of latent hyper- or hypoosmosis, hyperazotemia may develop (E. Kerpel-Froniusz, 1964).

An important indicator characterizing G. 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 oxygen saturation of the blood, 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 milk in its tissues. In addition, the immaturity of the acidogenetic function of the kidneys creates the prerequisites for the development of “physiological” acidosis (see). Due to the peculiarities of G., newborns often experience disorders that border between physiological and pathological.

Restructuring of the neuroendocrine system in the puberty period is also associated with changes in gland. However, the functions of the executive organs (kidneys, lungs) reach their maximum degree of maturity at this age, therefore severe syndromes or diseases of gland are rare, but more often we are talking about

about compensated changes in metabolism, which can only be detected with biochemical blood tests. In the clinic, to characterize G. in children, it is necessary to examine the following indicators: hematocrit, total osmotic pressure, content of sodium, potassium, sugar, bicarbonates and urea in the blood, as well as blood pH, pO 2 and pCO 2.

Features of homeostasis in old 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 the blood pressure level 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 physiol, functions is maintained in conditions of decreasing reliability and reduction of the possible range of physiol, changes in G. The preservation of relative G. with significant structural, metabolic and functional changes is achieved by the fact that at the same time not only extinction, disruption and degradation occurs, but also development of specific adaptive mechanisms. Due to this, a constant level of blood sugar, blood pH, osmotic pressure, cell membrane potential, etc. is maintained.

Changes in the mechanisms of neurohumoral regulation (see), an increase in the sensitivity of tissues to the action of hormones and mediators against the background of a weakening of nervous influences are of significant importance in preserving G. in the process of aging of the body.

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 natural trajectory (dynamics) of changes in the intensity of metabolism and physiol. functions with age over time. The significance of the course of age-related changes is very important for characterizing the aging process of a person, determining his biol, age.

In old age and old age, the general potential of adaptive mechanisms decreases. Therefore, in old age, under increased loads, stress, and other situations, the likelihood of failure of adaptation mechanisms and disruption of health increases. Such a decrease in the reliability of G.’s mechanisms is one of the most important prerequisites for the development of patol and disorders in old age.

Bibliography: Adolf E. Development of physiological regulations, trans. from English, M., 1971, bibliogr.; Anokhin P.K. Essays on the physiology of functional systems, M., 1975, bibliogr.; In e l t i-sh e in Yu. E., Samsygina G, A. and Ermakova I. A. On the characteristics of the osmoregulatory function of the kidneys in children of the newborn period, Pediatrics, No. 5, p. 46, 1975; Gellhorn E. Regulatory functions of the autonomic nervous system, trans. from English, M., 1948, bibliogr.; GlensdorfP. and Prigogine. Thermodynamic theory of structure" stability and fluctuations, trans. from English, M., 1973, bibliogr.; Homeostasis, ed. P. D. Gorizontova, M., 1976; Respiratory function of fetal blood in the obstetric clinic, ed. L. S. Persianinova et al., M., 1971; Kassil G.N. The problem of homeostasis in physiology and clinic, Vestn. Academy of Medical Sciences of the USSR, No. 7, p. 64, 1966, bibliogr.; Rozanova V.D. Essays on experimental age pharmacology, L., 1968, bibliogr.; F r about l-k and with V. V. Regulation, adaptation and aging, JI., 1970, bibliogr.; Stern L. S. Direct nutrient medium of organs and tissues, M., 1960; CannonW. B. Organization for physiological homeostasis, Physiol. Rev., v. 9, p. 399, 1929; Homeostatic regulators, ed. by G, E. W. Wolstenholme a. J. Knight, L., 1969; Langley L. L. Homeostasis, Stroudsburg, 1973.

G. N. Kassil; Yu. E. Veltishchev (ped.), B. N. Tarusov (biofiz.), V. V. Frolkis (ger.).

The term “homeostasis” comes from the word “homeostasis”, which means “force of stability”. Many people don’t hear about this concept often, or even at all. However, homeostasis is an important part of our lives, harmonizing contradictory conditions among themselves. And this is not just a part of our life, homeostasis is an important function of our body.

If we define the word homeostasis, the meaning of which is the regulation of the most important systems, then this is the ability that coordinates various reactions, allowing us to maintain balance. This concept applies to both individual organisms and entire systems.

In general, homeostasis is often discussed in biology. In order for the body to function properly and perform the necessary actions, it is necessary to maintain a strict balance in it. This is necessary not only for survival, but also so that we can properly adapt to environmental changes and continue to develop.

It is possible to distinguish the types of homeostasis necessary for a full-fledged existence - or, more precisely, the types of situations when this effect manifests itself.

• Instability. At this moment, we, namely our inner self, diagnose changes and, based on this, make decisions to adapt to new circumstances.
• Equilibrium. All our internal forces are aimed at maintaining balance.
• Unpredictability. We can often surprise ourselves by taking action we didn't expect.

All these reactions are determined by the fact that every organism on the planet wants to survive. The principle of homeostasis helps us understand the circumstances and make important decisions to maintain balance.

Unexpected decisions

Homeostasis has taken a strong place not only in biology. This term is also actively used in psychology. In psychology, the concept of homeostasis implies our response to external conditions. Nevertheless, this process closely links the adaptation of the body and individual mental adaptation.

Everything in this world strives for balance and harmony, and individual relationships with the environment tend toward harmonization. And this happens not only on the physical level, but also on the mental level. You can give the following example: a person laughs, but then he was told a very sad story, laughter is no longer appropriate. The body and emotional system are activated by homeostasis, calling for the correct response - and your laughter is replaced by tears.

As we see, the principle of homeostasis is based on a close connection between physiology and psychology. However, the principle of homeostasis associated with self-regulation cannot explain the sources of change.

The homeostatic process can be called the process of self-regulation. And this whole process occurs on a subconscious level. Our body has needs in many areas, but psychological contacts play an important role. Feeling the need to contact other organisms, a person shows his desire for development. This subconscious desire in turn reflects a homeostatic drive.

Very often such a process in psychology is called instinct. In fact, this is a very correct name, because all our actions are instincts. We cannot control our desires, which are dictated by instinct. Often our survival depends on these desires, or with their help the body requires what it is currently sorely lacking.

Imagine the situation: a group of deer is grazing not far from a sleeping lion. Suddenly the lion wakes up and roars, the fallow deer scatter. Now imagine yourself in the place of the doe. The instinct of self-preservation worked in her - she ran away. She must run very fast to save her life. This is psychological homeostasis.

But some time passes, and the doe begins to lose steam. Even though there might be a lion chasing after her, she would stop because the need to breathe was at the moment more important than the need to run. This is an instinct of the body itself, physiological homeostasis. Thus, the following types of homeostasis can be distinguished:

• Coercive.
• Spontaneous.

The fact that the doe started running is a spontaneous psychological urge. She had to survive, and she ran. And the fact that she stopped to catch her breath was coercion. The body forced the animal to stop, otherwise life processes could be disrupted.

The importance of homeostasis is very important for any organism, both psychologically and physically. A person can learn to live in harmony with himself and the environment without following only the urges of instincts. He only needs to correctly see and understand the world around him, as well as sort out his thoughts, placing priorities in the right order. Author: Lyudmila Mukhacheva

Homeostasis, homeostasis (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 (circulation, respiration, thermoregulation, metabolism and etc.) of the human and animal body. 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.

As is known, 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 external and 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 an integral 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

participation of nervous, humoral, metabolic and other factors. Many individual mechanisms regulating intra- and intercellular relationships have, in some cases, mutually opposite (antagonistic) 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 arise during the life of the organism.

The term “homeostasis” was proposed in 1929 by physiologist W. Cannon, who believed that the physiological processes that maintain stability in the body are so complex and diverse that it is advisable to combine them under the general name homeostasis. However, back in 1878, C. Bernard wrote that all life processes have only one goal - maintaining the constancy of living conditions in our internal environment. Similar statements are found in the works of many researchers of the 19th and first half of the 20th centuries. (E. Pfluger, S. Richet, Frederic (L.A. Fredericq), I.M. Sechenov, I.P. Pavlov, K.M. Bykov and others). The works of L.S. were of great importance for the study of the problem of homeostasis. Stern (with colleagues), devoted to the role of barrier functions that regulate the composition and properties of the microenvironment of organs and tissues.

The very idea of ​​homeostasis does not correspond to the concept of stable (non-fluctuating) equilibrium in the body - the principle of equilibrium does not apply to

complex physiological and biochemical

processes occurring in living systems. It is also incorrect to contrast homeostasis with rhythmic fluctuations in the internal environment. Homeostasis in a broad sense covers issues of the cyclic and phase course 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 flexible, changing depending on individual age, gender, social, professional and other conditions.

Of particular importance for the life of the body is the constancy of the composition of the blood - the fluid matrix of the body, as W. Cannon puts it. The stability of its active reaction (pH), osmotic pressure, ratio of electrolytes (sodium, calcium, chlorine, magnesium, phosphorus), glucose content, number of formed elements, and so on is well known. For example, blood pH, as a rule, does not go beyond 7.35-7.47. Even severe disorders of acid-base metabolism with pathology of acid accumulation in tissue fluid, for example in diabetic acidosis, have very little effect on the active blood reaction. 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 under certain severe pathological conditions.

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 characteristics, and the normal state of the 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 blood→tissue fluid, tissue fluid→blood.

The constancy of the internal environment for the activity of the central nervous system is of particular importance: even minor chemical and physicochemical changes that occur in the cerebrospinal fluid, glia and pericellular spaces can cause a sharp disruption in the flow of vital 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 optimal blood pressure levels. In this case, the upper limit of the blood pressure level is determined by the functionality of the baroreceptors of the body’s vascular system, and the lower limit is determined by the body’s blood supply needs.

The most advanced homeostatic mechanisms in the body of higher animals and humans include thermoregulation processes;