Homeostasis (Greek homoios - same, similar, stasis - stability, balance) is a set of coordinated reactions that ensure the maintenance or restoration of constancy internal environment body. In the mid-nineteenth century, the French physiologist Claude Bernard introduced the concept of the internal environment, which he considered as a collection of body fluids. This concept was expanded by the American physiologist Walter Cannon, who meant by the internal environment the entire set of fluids (blood, lymph, tissue fluid) that are involved in metabolism and maintaining homeostasis. The human body adapts to constantly changing environmental conditions, but the internal environment remains constant and its indicators fluctuate within very narrow limits. Therefore, a person can live in different environmental conditions. Some physiological parameters are regulated especially carefully and subtly, for example body temperature, blood pressure, glucose, gases, salts, calcium ions in the blood, acid-base balance, blood volume, its osmotic pressure, appetite many others. Regulation is carried out on the principle of negative feedback between receptors f, which detect changes in these indicators and control systems. Thus, a decrease in one of the parameters is captured by the corresponding receptor, from which impulses are sent to one or another structure of the brain, at the command of which the autonomic nervous system turns on complex mechanisms for equalizing the changes that have occurred. The brain uses two main systems to maintain homeostasis: autonomic and endocrine. Let us remind you that main function vegetative nervous system- this is the preservation of the constancy of the internal environment of the body, which is carried out due to changes in the activity of the sympathetic and parasympathetic parts of the autonomic nervous system. The latter, in turn, is controlled by the hypothalamus, and the hypothalamus by the cerebral cortex. The endocrine system regulates the function of all organs and systems through hormones. And she herself endocrine system is under the control of the hypothalamus and pituitary gland. Homeostasis (Greek homoios - identical and stasis - state, immobility)
As our ideas about normal, and even more so pathological, physiology became more complex, this concept was clarified as homeokinesis, i.e. moving equilibrium, balance of constantly changing processes. The body is woven from millions of “homeokinesics”. This huge living galaxy determines the functional status of all organs and cells that communicate with regulatory peptides. Like the global economic and financial systems - many firms, industries, factories, banks, exchanges, markets, shops... And between them - “convertible currency” - neuropeptides. All cells of the body constantly synthesize and maintain a certain, functionally necessary, level of regulatory peptides. But when deviations from “stationarity” occur, their biosynthesis (in the body as a whole or in its individual “loci”) either increases or decreases. Such fluctuations occur constantly when it comes to adaptive reactions (getting used to new conditions), performance of work (physical or emotional actions), the state of pre-illness - when the body “turns on” increased protection against disturbances in the functional balance. A classic case of maintaining balance is the regulation of blood pressure. There are groups of peptides between which there is constant competition - to increase / decrease blood pressure. In order to run, climb a mountain, steam in a sauna, perform on stage, and finally think, a functionally sufficient increase in blood pressure is necessary. But as soon as the work is over, regulators come into effect, ensuring “calmation” of the heart and normal pressure in the blood vessels. Vasoactive peptides constantly interact to “allow” the pressure to increase to such and such a level (no more, otherwise the vascular system will go “out of whack”; a well-known and bitter example is a stroke) and so that after the completion of physiologically necessary work
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 main physiological functions(blood circulation, respiration, thermoregulation, metabolism, and so on) 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, living cell represents a mobile, self-regulating system. Its internal organization is maintained active processes aimed at limiting, preventing or eliminating shifts caused by various influences from the surrounding 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 environment and changes that occur during the life of the body.
The term “homeostasis” was proposed in 1929 by the physiologist W. Cannon, who believed that physiological processes, maintaining stability in the body, are so complex and diverse that it is advisable to combine them under common 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 a pathology of accumulation of acids in tissue fluid, for example in diabetic acidosis, have very little effect on active reaction 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 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 normal condition organs depends on chemical composition, physicochemical, biological and other properties of this microenvironment. Its homeostasis is determined functional state histohematic barriers and their permeability in the directions blood→tissue fluid, tissue fluid→blood.
Especially important has a constancy of the internal environment for the activity of the central nervous system: even minor chemical and physico-chemical changes that occur in the cerebrospinal fluid, glia and pericellular spaces can cause sudden violation currents 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 optimal blood pressure levels. Wherein upper limit blood pressure level is determined by the functionality of baroreceptors vascular system body, and the lower limit is the body's needs for blood supply.
The most advanced homeostatic mechanisms in the body of higher animals and humans include thermoregulation processes;
Homeostasis(from Greek - similar, identical + state, immobility) - the relative dynamic constancy of the composition and properties of the internal environment and the stability of the basic physiological functions of a living organism; maintaining consistency species composition and the number of individuals in biocenoses; the ability of a population to maintain dynamic equilibrium genetic composition, which ensures its maximum viability. ( TSB)
Homeostasis- constancy of characteristics essential for the life of the system in the presence of disturbances in the external environment; a state of relative constancy; relative independence of the internal environment from external conditions.(Novoseltsev V.N.)
Homeostasis - the ability of an open system to maintain the constancy of its internal state through coordinated reactions aimed at maintaining dynamic equilibrium.
American physiologist Walter Bradford Cannon in 1932 in his book “The Wisdom of the Body(Wisdom of the Body) proposed this term as a name for "the coordinated physiological processes that support most of the body's steady states."
Word " homeostasis" can be translated as "the power of stability."
The term homeostasis is most often used in biology. Multicellular organisms need to maintain a constant internal environment to exist. Many ecologists are convinced that this principle also applies to the external environment. If the system is unable to restore its balance, it may eventually cease to function.
Complex systems—such as the human body—must have homeostasis in order to remain stable and exist. These systems not only must strive to survive, they also have to adapt to environmental changes and evolve.
Homeostatic systems have the following properties:
- Instability: the system tests how best to adapt.
- Striving for balance: the entire internal, structural and functional organization of systems contributes to maintaining balance.
- Unpredictability: the resulting effect of a certain action can often differ from what was expected.
Examples of homeostasis in mammals:
- Quantity regulation minerals and water in the body - osmoregulation. Carried out in the kidneys.
- Removal of waste products from the metabolic process - excretion. It is carried out by exocrine organs - kidneys, lungs, sweat glands.
- Regulation of body temperature. Lowering temperature through sweating, various thermoregulatory reactions.
- Regulation of blood glucose levels. Mainly carried out by the liver, insulin and glucagon secreted by the pancreas.
It is important to note that although the body is in equilibrium, its physiological state can be dynamic. Many organisms exhibit endogenous changes in the form of circadian, ultradian, and infradian rhythms. Thus, even when in homeostasis, body temperature, blood pressure, heart rate and most metabolic indicators are not always at a constant level, but change over time.
Homeostasis mechanisms: feedback
When a change occurs in variables, there are two main types of feedback that the system responds to:
1. Negative Feedback, expressed as a reaction in which the system responds in such a way as to reverse the direction of change. Since feedback serves to maintain the constancy of the system, it allows homeostasis to be maintained.
For example, when the concentration carbon dioxide increases in the human body, a signal comes to the lungs to increase their activity and exhale more quantity carbon dioxide.
Thermoregulation is another example of negative feedback. When body temperature rises (or falls), thermoreceptors in the skin and hypothalamus register the change, triggering a signal from the brain. This signal, in turn, causes a response - a decrease in temperature.
2. Positive Feedback, which is expressed in increasing the change in the variable. It has a destabilizing effect and therefore does not lead to homeostasis. Positive feedback is less common in natural systems, but it also has its uses.
For example, in nerves, a threshold electrical potential causes the generation of much greater potential actions. Blood clotting and events at birth can be cited as other examples of positive feedback.
Stable systems require combinations of both types of feedback. Whereas negative feedback allows a return to a homeostatic state, positive feedback is used to move to an entirely new (and perhaps less desirable) state of homeostasis, a situation called “metastability.” Such catastrophic changes can occur, for example, with an increase in nutrients in rivers with clear water, which leads to a homeostatic state of high eutrophication (overgrowth of the riverbed with algae) and turbidity.
Ecological homeostasis observed in climax communities with the maximum available biological diversity at favorable conditions environment.
In disturbed ecosystems, or subclimax biological communities - such as the island of Krakatoa, after a massive volcanic eruption in 1883 - the state of homeostasis of the previous forest climax ecosystem was destroyed, as was all life on that island. Krakatoa, in the years following the eruption, went through a chain of ecological changes in which new species of plants and animals succeeded each other, leading to biodiversity and the resulting climax community. Ecological succession on Krakatoa was carried out in several stages. The complete chain of successions leading to climax is called preseria. In the example of Krakatoa, a climax community with eight thousand people formed on this island. various types, registered in 1983, a hundred years after the eruption destroyed life on it. The data confirm that the situation remains in homeostasis for some time, with the emergence of new species very quickly leading to the rapid disappearance of old ones.
The case of Krakatoa and other disturbed or intact ecosystems shows that initial colonization by pioneer species occurs through positive feedback reproductive strategies in which species disperse, producing as many offspring as possible, but with little investment in the success of each individual. . In such species there is rapid development and equally rapid collapse (for example, through an epidemic). As an ecosystem approaches climax, such species are replaced by more complex climax species that, through negative feedback, adapt to the specific conditions of their environment. These species are carefully controlled by the potential carrying capacity of the ecosystem and follow a different strategy - the production of smaller offspring, the reproductive success of which in the conditions of the microenvironment of its specific ecological niche more energy is invested.
Development begins with the pioneer community and ends with the climax community. This climax community forms when flora and fauna come into balance with the local environment.
Such ecosystems form heterarchies in which homeostasis at one level contributes to homeostatic processes at another complex level. For example, the loss of leaves from a mature tropical tree provides space for new growth and enriches the soil. Equally, the tropical tree reduces light access to lower levels and helps prevent invasion by other species. But trees also fall to the ground and the development of the forest depends on the constant change of trees and the cycle of nutrients carried out by bacteria, insects, and fungi. Similarly, such forests contribute to ecological processes such as the regulation of microclimates or hydrological cycles of the ecosystem, and several different ecosystems may interact to maintain homeostasis of river drainage within a biological region. Bioregional variability also plays a role in the homeostatic stability of a biological region, or biome.
Biological homeostasis acts as a fundamental characteristic of living organisms and is understood as maintaining the internal environment within acceptable limits.
The internal environment of the body includes body fluids - blood plasma, lymph, intercellular substance and cerebrospinal fluid. Maintaining the stability of these fluids is vital for organisms, while its absence leads to damage to the genetic material.
With respect to any parameter, organisms are divided into conformational and regulatory. Regulatory organisms keep the parameter at a constant level, regardless of what happens in the environment. Conformational organisms allow the environment to determine the parameter. For example, warm-blooded animals retain constant temperature bodies, then cold-blooded animals exhibit a wide range of temperatures.
This is not to say that conformational organisms do not have behavioral adaptations that allow them to regulate a given parameter to some extent. Reptiles, for example, often sit on heated rocks in the morning to raise their body temperature.
The benefit of homeostatic regulation is that it allows the body to function more efficiently. For example, cold-blooded animals tend to become lethargic when low temperatures, while warm-blooded animals are almost as active as ever. On the other hand, regulation requires energy. The reason why some snakes can only eat once a week is because they expend much less energy to maintain homeostasis than mammals.
Homeostasis in the human body
Various factors influence the ability of body fluids to support life, including parameters such as temperature, salinity, acidity, and the concentration of nutrients - glucose, various ions, oxygen, and waste products - carbon dioxide and urine. Since these parameters affect chemical reactions, which keep the body alive, there are built-in physiological mechanisms to maintain them at the required level.
Homeostasis cannot be considered the cause of these unconscious adaptation processes. It should be taken as general characteristics many normal processes acting together, and not as their root cause. Moreover, there are many biological phenomena that do not fit this model - for example, anabolism. ( From the Internet)
Homeostasis- relative dynamic stability of the characteristics of the internal environment of biological and social (suprabiological) objects.
In relation to to the company homeostasis- this is sustainability internal processes with a minimum of staff effort. ( Korolev V.A.)
Homeostat
Homeostat- a mechanism for maintaining the dynamic constancy of the functioning of the system within specified limits.
(Stepanov A.M.)
Homeostat(ancient Greek - similar, identical + standing, motionless) - a mechanism for ensuring homeostasis, an ensemble of signal-regulatory connections that coordinate the activity and interaction of parts companies, and also correct her behavior in relations with a changeable external environment in order to ensure homeostasis. Synonymous with the archaic term “management”, which in companies lower levels evolution is traditionally understood as command and, accordingly, a mechanism for ensuring the passage and execution of commands; those. performing only part of the homeostatic functions. ( Korolev V.A.)
Homeostat- a self-organizing system that models the ability of living organisms to maintain certain values within physiologically acceptable limits. Proposed in 1948 by the English scientist in the fields of biology and cybernetics W. R. Ashby, who designed it in the form of a device consisting of four electromagnets having cross feedbacks. (TSB)
Homeostat- an analog electromechanical device that simulates the ability of living organisms to maintain some of their characteristics (for example, body temperature, oxygen content in the blood) within acceptable limits. The homeostatic principle is used to determine optimal values parameters technical systems automatic regulation (eg autopilots). ( BEKM)
"In connection with the question of the effective amount of public information, it should be noted as one of the most amazing facts V life of the state, that there are very few effective homeostatic processes
. In many countries, it is widely believed that free competition is itself a homeostatic process, i.e. that in a free market the selfishness of the traders, each striving to sell as high as possible and buy as cheap as possible, will ultimately lead to a stable movement of prices and promote the greatest common good. This opinion is related to the “comforting” view that self employed, seeking to secure his own benefit, is in some way a public benefactor and therefore deserves the great rewards with which society showers him. Unfortunately, the facts speak against this simple-minded theory.
The market is a game. It is strictly subordinated to the general game theory, which was developed by von Neumann and Morgenstern. This theory is based on the assumption that at any stage of the game, each player, based on the information available to him, plays according to a completely reasonable strategy, which in the end should provide him with the greatest expected value winning. This is a market game played by completely reasonable and completely shameless businessmen. Even with two players, the theory is complex, although it often leads to the choice of a certain direction of play. But with three players in many cases, and with many players in the vast majority of cases the outcome of the game is characterized by extreme uncertainty and instability. Driven by their own greed, individual players form coalitions; but these coalitions are usually not established in any one particular way and usually end in a pandemonium of betrayals, renegades and deceptions. This is an accurate picture of the highest business life and the political, diplomatic and military life closely connected with it. In the end, even the most brilliant and unscrupulous broker will face ruin. But let’s say that the brokers got tired of this and agreed to live in peace among themselves. Then the reward will go to the one who, choosing the right moment, breaks the agreement and betrays his partners. There is no homeostasis here. We must go through the cycles of boom and bust in business life, the successive changes of dictatorship and revolution, the wars in which everyone loses and which are so characteristic of our time.
Of course, the image of the player drawn by von Neumann as a completely reasonable and completely shameless person represents an abstraction and a distortion of reality. It is rare to find that big number quite reasonable and unprincipled people played together. Where swindlers gather, there are always fools; and if there is sufficient quantity fools, they represent a more profitable object of exploitation for scammers. The psychology of a fool has become an issue worthy of serious attention from scammers. Instead of pursuing his ultimate gain, like von Neumann's gamblers, the fool acts in a way that is generally as predictable as a rat's attempts to find its way through a maze. The illustrated newspaper will be sold by some precisely defined mixture of religion, pornography and pseudoscience. A combination of ingratiation, bribery and intimidation will force a young scientist to work on guided missiles or an atomic bomb. To determine the recipes for these mixtures, there is a mechanism for radio polls, preliminary voting, sample public opinion surveys and others. psychological research, the object of which is a simple person; and there are always statisticians, sociologists and economists ready to sell their services to these enterprises.
Small, tightly knit communities have high degree homeostasis, whether these will be cultural communities in a civilized country or villages of primitive savages. No matter how strange and even repulsive the customs of many barbarian tribes may seem to us, these customs, as a rule, have a very definite homeostatic value, the explanation of which is one of the tasks of anthropologists. Only in a large community, where the Lords of the Real State of Things protect themselves from hunger by their wealth, from public opinion by secrecy and anonymity, from private criticism by laws against libel and the fact that the means of communication are at their disposal, only in such a community can shamelessness achieve top level. Of all these antihomeostatic social factors communications management is the most effective and important."
(N. Wiener. Cybernetics. 1948)
CERTICOM Management consulting
Homeostasis
Homeostasis, homeorez, homeomorphosis - characteristics of the state of the body. The systemic essence of the organism is manifested primarily in its ability to self-regulate in continuously changing environmental conditions. Since all organs and tissues of the body consist of cells, each of which is a relatively independent organism, the state of the internal environment human body It has great value for its normal functioning. For the human body - a land creature - the environment consists of the atmosphere and the biosphere, while it interacts to a certain extent with the lithosphere, hydrosphere and noosphere. At the same time, most cells human body immersed in a liquid medium, which is represented by blood, lymph and intercellular fluid. Only integumentary tissues directly interact with surrounding a person environment, all other cells are isolated from outside world, which allows the body to largely standardize the conditions of their existence. In particular, the ability to maintain a constant body temperature of about 37 ° C ensures the stability of metabolic processes, since all biochemical reactions that constitute the essence of metabolism are very dependent on temperature. It is equally important to support liquid media In the body there is a constant tension of oxygen, carbon dioxide, the concentration of various ions, etc. Under normal conditions of existence, including during adaptation and activity, small deviations of these kinds of parameters arise, but they are quickly eliminated, and the internal environment of the body returns to a stable norm. The great French physiologist of the 19th century. Claude Bernard argued: “The constancy of the internal environment is an indispensable condition for a free life.” Physiological mechanisms that ensure the maintenance of a constant internal environment are called homeostatic, and the phenomenon itself, which reflects the body’s ability to self-regulate the internal environment, is called homeostasis. This term was introduced in 1932 by W. Cannon, one of those physiologists of the 20th century who, along with N.A. Bernstein, P.K. Anokhin and N. Wiener, stood at the origins of the science of control - cybernetics. The term “homeostasis” is used not only in physiological, but also in cybernetic research, since it is the maintenance of constancy of any characteristics of a complex system that is main goal any control.
Another remarkable researcher, K. Waddington, drew attention to the fact that the body is capable of maintaining not only the stability of its internal state, but also the relative constancy of dynamic characteristics, i.e., the course of processes over time. This phenomenon, by analogy with homeostasis, was called homeorez. It is of particular importance for a growing and developing organism and consists in the fact that the organism is able to preserve (in within certain limits, of course) “development channel” in the course of its dynamic transformations. In particular, if a child, due to illness or a sharp deterioration in living conditions caused by social reasons(war, earthquake, etc.) significantly lags behind their normally developing peers, this does not mean that such a lag is fatal and irreversible. If the period of unfavorable events ends and the child receives conditions adequate for development, then both in terms of growth and level functional development he soon catches up with his peers and subsequently does not differ significantly from them in any way. This explains the fact that those who were transferred to early age severe illness, children often grow into healthy and well-proportioned adults. Homeorez plays vital role both in the control of ontogenetic development and in adaptation processes. Meanwhile, the physiological mechanisms of homeoresis have not yet been sufficiently studied.
The third form of self-regulation of body constancy is homeomorphosis - the ability to maintain a constant form. This characteristic in to a greater extent inherent in an adult organism, since growth and development are incompatible with the immutability of form. Nevertheless, if we consider short periods of time, especially during periods of growth inhibition, then the ability to homeomorphosis can be found in children. It's about that in the body there is a continuous change of generations of its constituent cells. Cells do not live long (the only exception is nerve cells): The normal lifespan of body cells is weeks or months. Nevertheless, each new generation of cells almost exactly repeats the shape, size, location and, accordingly, functional properties of the previous generation. Special physiological mechanisms prevent significant changes in body weight under conditions of fasting or overeating. In particular, during fasting, the digestibility of nutrients sharply increases, and during overeating, on the contrary, most of the proteins, fats and carbohydrates supplied with food are “burned” without any benefit to the body. It has been proven (N.A. Smirnova) that in an adult, sharp and significant changes in body weight (mainly due to the amount of fat) in any direction are sure signs failure of adaptation, overexertion and indicate functional dysfunction of the body. Children's body becomes especially sensitive to external influences during periods of the most rapid growth. Violation of homeomorphosis is the same unfavorable sign as violations of homeostasis and homeoresis.
The concept of biological constants. The body is a complex of a huge number of different substances. During the life of the body's cells, the concentration of these substances can change significantly, which means a change in the internal environment. It would be unthinkable if the body's control systems were forced to monitor the concentration of all these substances, i.e. have many sensors (receptors), continuously analyze Current state, make management decisions and monitor their effectiveness. Neither the information nor the energy resources of the body would be sufficient for such a mode of controlling all parameters. Therefore, the body is limited to monitoring a relatively small number of the most significant indicators, which must be maintained at a relatively constant level for the well-being of the vast majority of cells in the body. These most strictly homeostasis parameters are thereby transformed into “biological constants,” and their immutability is ensured by sometimes quite significant fluctuations in other parameters that are not classified as homeostasis. Thus, the levels of hormones involved in the regulation of homeostasis can change in the blood tens of times depending on the state of the internal environment and exposure external factors. At the same time, homeostasis parameters change only by 10-20%.
The most important biological constants. Among the most important biological constants, for the maintenance of which at a relatively constant level, various physiological systems organism should be called body temperature, blood glucose level, H+ ion content in body fluids, partial tension of oxygen and carbon dioxide in tissues.
Disease as a sign or consequence of homeostasis disorders. Almost all human diseases are associated with disruption of homeostasis. For example, in many infectious diseases, as well as in the case of inflammatory processes, temperature homeostasis in the body is sharply disrupted: fever (fever) occurs, sometimes life-threatening. The reason for this disruption of homeostasis may lie both in the characteristics of the neuroendocrine reaction and in disturbances in the activity of peripheral tissues. In this case, the manifestation of the disease - elevated temperature - is a consequence of a violation of homeostasis.
Typically, febrile conditions are accompanied by acidosis - a violation of the acid-base balance and a shift in the reaction of body fluids to the acidic side. Acidosis is also characteristic of all diseases associated with deterioration of the cardiovascular and respiratory systems(diseases of the heart and blood vessels, inflammatory and allergic lesions of the bronchopulmonary system, etc.). Acidosis often accompanies the first hours of a newborn’s life, especially if he did not begin to breathe normally immediately after birth. To eliminate this condition, the newborn is placed in a special chamber with a high oxygen content. Metabolic acidosis in severe muscle load can occur in people of any age and manifests itself in shortness of breath and increased sweating, as well as pain in the muscles. After completion of work, the state of acidosis can persist from several minutes to 2-3 days, depending on the degree of fatigue, fitness and the effectiveness of homeostatic mechanisms.
Diseases that lead to disruption of water-salt homeostasis are very dangerous, for example cholera, in which it is removed from the body. great amount water and tissue lose their functional properties. Many kidney diseases also lead to disruption of water-salt homeostasis. As a result of some of these diseases, alkalosis may develop - an excessive increase in the concentration of alkaline substances in the blood and an increase in pH (a shift to the alkaline side).
In some cases, minor but long-term disturbances in homeostasis can cause the development of certain diseases. Thus, there is evidence that excessive consumption of sugar and other sources of carbohydrates that disrupt glucose homeostasis leads to damage to the pancreas, as a result of which a person develops diabetes. Excessive consumption of table and other mineral salts is also dangerous, spicy seasonings etc., increasing the load on excretory system. The kidneys may not be able to cope with the abundance of substances that need to be removed from the body, resulting in a disruption of water-salt homeostasis. One of its manifestations is edema - the accumulation of fluid in the soft tissues of the body. The cause of edema usually lies either in insufficiency of cardio-vascular system, or in disorders of the kidneys and, as a consequence, mineral metabolism.
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 physico-chemical 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;
