What is responsible for maintaining homeostasis. Homeostasis is its biological significance. Use in medicine

Homeostasis is a process that occurs independently in the body and is aimed at stabilizing the state of human systems when changing internal conditions(changes in temperature, pressure) or external (changes in climate, time zone). This name was proposed by the American physiologist Cannon. Subsequently, homeostasis began to be called the ability of any system (including the environment) to maintain its internal constancy.

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The concept and characteristics of homeostasis

Wikipedia characterizes this term as the desire to survive, adapt and develop. In order for homeostasis to be correct, the coordinated work of all organs and systems is needed. In this case, all parameters in a person will be normal. If some parameter is not regulated in the body, this indicates a violation of homeostasis.

The main characteristics of homeostasis are as follows:

• analysis of the possibilities of adapting the system to new conditions;
• the desire to maintain balance;
• the impossibility of predicting the results of the regulation of indicators in advance.

Feedback

Feedback is the actual mechanism of action of homeostasis. Thus the body reacts to any changes. The body functions continuously throughout a person's life. However, individual systems must have time to rest and recover. During this period, the work of individual organs slows down or stops altogether. This process is called feedback. Its example is a break in the work of the stomach, when food does not enter it. Such a break in digestion provides a stop in the production of acid due to the action of hormones and nerve impulses.

There are two types of this mechanism, which will be described next.

negative feedback

This type of mechanism is based on the fact that the body reacts to changes, trying to direct them in the opposite direction. That is, it strives again for stability. For example, if carbon dioxide accumulates in the body, the lungs begin to work more actively, breathing quickens, due to which excess carbon dioxide is removed. carbon dioxide. And also it is thanks to the negative feedback that thermoregulation is carried out, due to which the body avoids overheating or hypothermia.

positive feedback

This mechanism is directly opposite to the previous one. In the case of its action, the change in the variable is only amplified by the mechanism, which brings the organism out of equilibrium. This is a rather rare and less desirable process. An example of this is the presence of electrical potential in nerves., which instead of decreasing the action, leads to its increase.

However, thanks to this mechanism, development and transition to new states occur, which means that it is also necessary for life.

What parameters does homeostasis regulate?

Despite the fact that the body is constantly trying to maintain the values ​​of parameters important for life, they are not always stable. Body temperature will still change within a small range, as will heart rate or blood pressure. The task of homeostasis is to maintain this range of values, as well as help in the functioning of the body.

Examples of homeostasis are the excretion of waste products from the human body, carried out by the kidneys, sweat glands, gastrointestinal tract, as well as the dependence of metabolism on diet. A little more about the adjustable parameters will be discussed later.

Body temperature

The clearest and simplest example of homeostasis is the maintenance of normal body temperature. Overheating of the body can be avoided by sweating. The normal temperature range is 36 to 37 degrees Celsius. An increase in these values ​​\u200b\u200bcan be triggered by inflammatory processes, hormonal and metabolic disorders, or any diseases.

The part of the brain called the hypothalamus is responsible for controlling body temperature in the body. There are signals about the failure of the temperature regime, which can also be expressed in rapid breathing, an increase in the amount of sugar, an unhealthy acceleration of metabolism. All this leads to lethargy, a decrease in the activity of the organs, after which the systems begin to take measures to regulate temperature indicators. A simple example of the body's thermoregulatory response is sweating..

It is worth noting that this process also works with an excessive decrease in body temperature. So the body can warm itself due to the breakdown of fats, in which heat is released.

Water-salt balance

Water is necessary for the body, and everyone knows this well. There is even a norm of daily fluid intake, in the amount of 2 liters. In fact, each organism needs its own amount of water, and for some it may exceed the average value, while for others it may not reach it. However, no matter how much water a person drinks, the body will not accumulate all the excess fluid. Water will remain at the required level, while all the excess will be removed from the body due to osmoregulation carried out by the kidneys.

Blood homeostasis

In the same way, the amount of sugar, namely glucose, which is an important element of the blood, is regulated. A person cannot be completely healthy if the sugar level is far from normal. This indicator is regulated by the functioning of the pancreas and liver. In the case when the glucose level exceeds the norm, the pancreas acts, in which insulin and glucagon are produced. If the amount of sugar becomes too low, glycogen from the blood is processed into it with the help of the liver.

normal pressure

Homeostasis is also responsible for the normal blood pressure in the body. If it is broken, signals about this will come from the heart to the brain. The brain reacts to the problem and, with the help of impulses, helps the heart to reduce high pressure.

The definition of homeostasis characterizes not only the correct functioning of the systems of one organism, but can also apply to entire populations. Depending on this, there are types of homeostasis described below.

Ecological homeostasis

This type is present in the provided necessary conditions community life. It arises through the action of a positive feedback mechanism, when organisms that begin to inhabit an ecosystem multiply rapidly, thereby increasing their numbers. But such a rapid settlement can lead to an even faster destruction of a new species in the event of an epidemic or a change in conditions to less favorable ones. So organisms need to adapt and stabilize, which is due to negative feedback. Thus, the number of inhabitants decreases, but they become more adapted.

Biological homeostasis

This type is just typical for individuals whose body strives to maintain internal balance, in particular, by regulating the composition and amount of blood, intercellular substance and other fluids necessary for the normal functioning of the body. At the same time, homeostasis does not always oblige to keep the parameters constant, sometimes it is achieved by adapting and adapting the body to changing conditions. Due to this difference, organisms are divided into two types:

• conformational - those who strive to preserve values ​​(for example, warm-blooded animals, whose body temperature should be more or less constant);
• regulatory, which adapt (cold-blooded, having a different temperature depending on the conditions).

At the same time, the homeostasis of each of the organisms is aimed at compensating for the costs. If warm-blooded animals do not change their lifestyle when the ambient temperature drops, then cold-blooded animals become lethargic and passive so as not to waste energy.

Besides, Biological homeostasis includes the following subspecies:

• cellular homeostasis is aimed at changing the structure of the cytoplasm and the activity of enzymes, as well as the regeneration of tissues and organs;
• homeostasis in the body is ensured by regulating temperature indicators, the concentration of substances necessary for life, and the removal of waste.

Other types

In addition to use in biology and medicine, the term has found application in other areas.

Maintenance of homeostasis

Homeostasis is maintained due to the presence in the body of so-called sensors that send impulses to the brain containing information about pressure and body temperature, water-salt balance, blood composition and other parameters important for normal life. As soon as some values ​​begin to deviate from the norm, a signal about this enters the brain, and the body begins to regulate its performance.

This complex adjustment mechanism incredibly important to life. The normal state of a person is maintained with the correct ratio of chemicals and elements in the body. Acids and alkalis are necessary for the stable functioning of the digestive system and other organs.

Calcium is a very important structural material, without the right amount of which a person will not have healthy bones and teeth. Oxygen is essential for breathing.

Toxins can interfere with the smooth functioning of the body. But so that health is not harmed, they are excreted due to the work of the urinary system.

Homeostasis works without any human effort. If the body is healthy, the body will self-regulate all processes. If people are hot, the blood vessels dilate, which is expressed in reddening of the skin. If it's cold - there is a shiver. Thanks to such responses of the body to stimuli, human health is maintained at the right level.

Homeostasis is any self-regulating process by which biological systems strive to maintain internal stability by adapting to optimal conditions for survival. If homeostasis is successful, then life goes on; otherwise, disaster or death will occur. The achieved stability is in fact a dynamic equilibrium in which continuous changes occur, but relatively homogeneous conditions prevail.

Features and role of homeostasis

Any system in dynamic equilibrium wants to achieve a stable state, a balance that resists external changes. When such a system is disturbed, the built-in regulatory devices react to deviations in order to establish a new balance. Such a process is one of the elements of feedback control. Examples of homeostatic regulation are all processes of integration and coordination of functions mediated by electrical circuits and nervous or hormonal systems.

Another example of homeostatic regulation in a mechanical system is the operation of a room temperature controller or thermostat. The heart of the thermostat is a bimetallic strip that responds to temperature changes by completing or breaking an electrical circuit. When the room cools down, the circuit is completed and the heating is turned on, and the temperature rises. At the set level, the circuit is interrupted, the oven stops and the temperature drops.

However, biological systems, which are of great complexity, have regulators that are difficult to compare with mechanical devices.

As noted earlier, the term homeostasis refers to the maintenance of the internal environment of the body within narrow and tightly controlled limits. The main functions important for maintaining homeostasis are fluid and electrolyte balance, acid regulation, thermoregulation, and metabolic control.

Body temperature control in humans is considered an excellent example of homeostasis in biological system. The normal human body temperature is around 37°C, but various factors can affect this, including hormones, metabolic rate, and diseases that lead to excessively high or low temperatures. Body temperature regulation is controlled by an area of ​​the brain called the hypothalamus.

Feedback about body temperature is carried through the bloodstream to the brain and results in compensatory adjustments in breathing rate, blood sugar levels, and metabolic rate. Heat loss in humans is mediated by reduced activity, sweating, and heat transfer mechanisms that allow more blood to circulate near the surface of the skin.

Heat loss is reduced through insulation, reduced circulation on the skin, and cultural changes such as the use of clothing, housing, and third-party heat sources. The range between high and low levels of body temperature constitutes the homeostatic plateau - the "normal" range that sustains life. As either of the two extremes is approached, corrective action (via negative feedback) brings the system back into the normal range.

The concept of homeostasis also applies to environmental conditions. First proposed by the American ecologist Robert MacArthur in 1955, the idea that homeostasis is the product of a combination of biodiversity and the many ecological interactions that occur between species.

Such an assumption was considered a concept that could help explain the sustainability of an ecological system, that is, its persistence as a particular type of ecosystem over time. Since then, the concept has changed somewhat, and included the non-living component of the ecosystem. The term has been used by many ecologists to describe the reciprocity that occurs between the living and non-living components of an ecosystem to maintain the status quo.

The Gaia Hypothesis is a model of the Earth proposed by the English scientist James Lovelock, which considers various living and non-living components as components of a larger system or a single organism, suggesting that the collective efforts of individual organisms contribute to homeostasis at the planetary level.

Cellular homeostasis

Depend on the environment of the body to stay alive and function properly. Homeostasis maintains the body's environment under control and maintains favorable conditions for cellular processes. Without the right body conditions, certain processes (eg osmosis) and proteins (eg enzymes) will not function properly.

Why is homeostasis important for cells? Living cells depend on the movement of chemicals around them. Chemicals such as oxygen, carbon dioxide, and dissolved food need to be transported in and out of cells. This is carried out by the processes of diffusion and osmosis, which depend on the balance of water and salt in the body, which are maintained by homeostasis.

Cells depend on enzymes to speed up many chemical reactions that support the vitality and functionality of cells. These enzymes work best at certain temperatures and so again homeostasis is vital for cells as it maintains a constant body temperature.

Examples and mechanisms of homeostasis

Here are some basic examples of homeostasis in the human body, as well as the mechanisms that support them:

Body temperature

The most common example of homeostasis in humans is the regulation of body temperature. Normal body temperature, as we wrote above, is 37 ° C. Temperatures above or below normal can cause serious complications.

Muscle failure occurs at a temperature of 28 ° C. At 33 ° C, loss of consciousness occurs. At a temperature of 42 ° C, the central nervous system begins to collapse. Death occurs at 44°C. The body controls temperature by producing or releasing excess heat.

Glucose concentration

Glucose concentration refers to the amount of glucose (blood sugar) present in the bloodstream. The body uses glucose as an energy source, but too much or too little can cause serious complications. Some hormones regulate the concentration of glucose in the blood. Insulin lowers the concentration of glucose, while cortisol, glucagon and catecholamines increase it.

Calcium levels

Bones and teeth contain approximately 99% of the calcium in the body, while the remaining 1% circulates in the blood. Too much or too little calcium in the blood has negative consequences. If blood calcium levels drop too low, the parathyroid glands activate their calcium-sensing receptors and release parathyroid hormone.

PTH signals to the bones that it needs to release calcium in order to increase its concentration in the bloodstream. If calcium levels increase too much, the thyroid gland releases calcitonin and fixes the excess calcium in the bones, thereby reducing the amount of calcium in the blood.

Liquid volume

The body must maintain a constant internal environment, which means it needs to regulate fluid loss or replenishment. Hormones help regulate this balance by causing excretion or fluid retention. If the body does not have enough fluid, antidiuretic hormone signals the kidneys to conserve fluid and reduces urine output. If the body contains too much fluid, it suppresses aldosterone and signals release more urine.

They 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 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 bases, 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.

As is known, living cell represents 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 (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 occur during the life of the organism.

The term "homeostasis" was proposed in 1929 by the 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 of homeostasis. However, back in 1878, K. Bernard wrote that all life processes have only one goal - to maintain the constancy of living conditions in our internal environment. Similar statements are found in the works of many researchers of the 19th and the first half of the 20th century. (E. Pfluger, S. Richet, L.A. Fredericq, I.M. Sechenov, I.P. Pavlov, K.M. Bykov and others). The works of L.S. Stern (with collaborators), 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) 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 (fluid matrix), 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, and so on are well known. So, for example, blood pH, as a rule, does not go beyond 7.35-7.47. Even severe disorders of acid-base metabolism with a pathology of acid accumulation 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 (see Water-salt metabolism). 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 in 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 the organs depends on 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.

Various researchers explain the mechanisms of a general biological nature that underlie homeostasis in different ways. So, W. Cannon attached special importance to the higher nervous system, L. A. Orbeli considered the adaptive-trophic function of the sympathetic nervous system to be one of the leading factors of homeostasis. The organizing role of the nervous apparatus (the principle of nervism) underlies the well-known ideas about the essence of the principles of homeostasis (I. M. Sechenov, I. P. Pavlov, A. D. Speransky and others). 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 homeostasis (N. I. Grashchenkov) and many other theories do not 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” and the like appeared 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. Some authors consider the internal environment of the body as a complex chain system with many "active inputs" (internal organs) and individual physiological indicators (blood flow, blood pressure, gas exchange, etc.), the value of each of which is due to the activity of the "inputs".

In practice, researchers and clinicians face the questions 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 under stressful and extreme influences, and so on.

To assess the state of homeostatic mechanisms in fiziol. experiment and in a wedge, practice various dosed functional tests are applied (cold, thermal, adrenaline, insulin, mezaton and others) with definition in blood and urine of a parity of biologically active substances (hormones, mediators, metabolites) and so on.

Biophysical mechanisms of homeostasis

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 it is possible to establish a stationary course of physicochemical processes, that is, homeostasis, in a biological system. 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, and so on.

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

Age features of homeostasis in children. The constancy of the internal environment of the body and the relative stability of physico-chemical 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 (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 the volume of liquid (volume regulation) provides compensation for deviations in the water balance within fairly narrow limits. High degree tissue hydration in newborns and young children determines a significantly higher than in adults, the child's need for water (per unit body weight). Loss of water or its limitation quickly lead to the development of dehydration due to the extracellular sector, that is, 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 impact 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 varies over a wider range (±50 mosm/l) than in adults ±6 mosm/l). This is due to the greater body surface per 1 kg of weight and, consequently, more significant water loss during respiration, as well as 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 night diseases. Less studied is the ionic regulation of homeostasis, 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 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 (E. Kerpel-Froniusz, 1964).

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. 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 in 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, pO 2 and pCO 2.

Features of homeostasis in the elderly and senile age

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. During 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. 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, and so on are 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, and others 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 over 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.

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Homeostasis is the ability of the human body to adapt to changing conditions of the external and internal environment. Stable work of homeostasis processes guarantees a person a comfortable state of health in any situation, maintaining the constancy of vital signs of the body.

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:

1. Genetic.
2. Physiological.
3. 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 unexpected 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, someone has to wait a bit 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 nervous system from constant overvoltage.
• Watch 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.