What structures ensure self-regulation of homeostasis. The concept of homeostasis. Manifestation of homeostasis at different levels of organization of biological systems. Structural homeostasis, mechanisms of its maintenance. So, homeostasis is

History of the development of the doctrine of homeostasis

K. Bernard and his role in the development of the doctrine of the internal environment

For the first time, homeostatic processes in the body as processes ensuring the constancy of its internal environment were considered by the French naturalist and physiologist C. Bernard in the middle of the 19th century. The term itself homeostasis was proposed by the American physiologist W. Cannon only in 1929.

In the formation of the doctrine of homeostasis, the leading role was played by C. Bernard’s idea that for a living organism there are “actually two environments: one external environment in which the organism is placed, the other internal environment in which tissue elements live.” In 1878, the scientist formulated the concept of the constancy of the composition and properties of the internal environment. The key idea of ​​this concept was the idea that the internal environment consists not only of blood, but also of all the plasmatic and blastomatic fluids that come from it. “The internal environment,” wrote K. Bernard, “... is formed from all the components of the blood - nitrogenous and non-nitrogenous, protein, fibrin, sugar, fat, etc., ... with the exception of blood globules, which are already independent organic elements.”

The internal environment includes only the liquid components of the body, which wash all tissue elements, i.e. blood plasma, lymph and tissue fluid. C. Bernard considered the attribute of the internal environment to be “in direct contact with the anatomical elements of a living being.” He noted that when studying the physiological properties of these elements, it is necessary to consider the conditions of their manifestation and their dependence on the environment.

The scientist rightly believed that the manifestations of life are caused by a conflict between the existing forces of the body (constitution) and the influence external environment. The life conflict in the body manifests itself in the form of two opposing and dialectically related phenomena: synthesis and decay. As a result of these processes, the body adapts, or adapts, to environmental conditions.

An analysis of the works of C. Bernard allows us to conclude that all physiological mechanisms, no matter how different they may be, serve to maintain the constancy of living conditions in the internal environment. “The constancy of the internal environment is a condition for a free, independent life. This is achieved through a process that maintains in the internal environment all the conditions necessary for the life of the elements." The constancy of the environment presupposes such perfection of the organism in which external variables would be compensated and balanced at every moment. For a liquid medium, the basic conditions for its constant maintenance were determined: the presence of water, oxygen, nutrients and a certain temperature.

The independence of life from the external environment, which C. Bernard spoke about, is very relative. The internal environment is closely related to the external one. Moreover, it has retained many of the properties of the primary environment in which life once originated. Living beings, as it were, closed sea water into a system of blood vessels and turned the constantly fluctuating external environment into an internal environment, the constancy of which is protected by special physiological mechanisms.

The main function of the internal environment is to bring “organic elements into relationship with each other and with the external environment.” K. Bernard explained that there is a constant exchange of substances between the internal environment and the cells of the body due to their qualitative and quantitative differences inside and outside the cells. The internal environment is created by the body itself, and the constancy of its composition is maintained by the organs of digestion, respiration, excretion, etc., main function which is to “prepare a general nutrient fluid” for the cells of the body. The activity of these organs is regulated by the nervous system and with the help of “specially produced substances.” This “contains a continuous circle of mutual influences that form vital harmony.”

Thus, back in the second half of the 19th century, C. Bernard gave the correct scientific definition of the internal environment of the body, identified its elements, described its composition, properties, evolutionary origin and emphasized its importance in ensuring the life of the body.

The doctrine of homeostasis by W. Cannon

Unlike K. Bernard, whose conclusions were based on broad biological generalizations, W. Cannon came to the conclusion about the importance of the constancy of the internal environment of the body using another method: on the basis of experimental physiological studies. The scientist drew attention to the fact that the life of animals and humans, despite quite frequent adverse effects, proceeds normally for many years.

W. Cannon noted that the constant conditions maintained in the body could be called balance. However, this word has previously had a very specific meaning: it denotes the most probable state of an isolated system, in which all known forces are mutually balanced, therefore, in an equilibrium state, the parameters of the system do not depend on time, and there are no flows of matter or energy in the system. Complex coordinated physiological processes constantly occur in the body, ensuring the stability of its states. An example is the coordinated activity of the brain, nerves, heart, lungs, kidneys, spleen and others internal organs and systems. Therefore, W. Cannon proposed a special designation for such states - homeostasis. This word does not at all imply something frozen and motionless. It means a condition that can change but still remain relatively constant.

Term homeostasis formed from two Greek words: homoios– similar, similar and stasis- standing, immobility. In the interpretation of this term, W. Cannon emphasized that the word stasis implies not only a stable state, but also a condition leading to this phenomenon, and the word homoios indicates the similarity and similarity of phenomena.

The concept of homeostasis, according to W. Cannon, also includes physiological mechanisms that ensure the stability of living beings. This special stability is not characterized by the stability of processes; on the contrary, they are dynamic and constantly changing, however, under “normal” conditions, fluctuations in physiological indicators are quite strictly limited.

Later, W. Cannon showed that all metabolic processes and basic conditions under which the most important vital functions of the body are performed - body temperature, glucose concentration and mineral salts in blood plasma, pressure in blood vessels fluctuate within very narrow limits near certain average values ​​- physiological constants. Maintaining these constants in the body is a prerequisite for existence.

W. Cannon identified and classified main components of homeostasis. He referred to them materials that provide cellular needs(materials necessary for growth, restoration and reproduction - glucose, proteins, fats; water; sodium, potassium chlorides and other salts; oxygen; regulatory compounds), and physical and chemical factors, affecting cellular activity (osmotic pressure, temperature, concentration of hydrogen ions, etc.). At the present stage of development of knowledge about homeostasis, this classification has been expanded mechanisms that ensure the structural constancy of the internal environment of the body and structural and functional integrity the whole body. These include:

a) heredity;
b) regeneration and repair;
c) immunobiological reactivity.

Terms automatic maintaining homeostasis, according to W. Cannon, are:

– a flawlessly functioning alarm system that notifies central and peripheral regulatory devices of any changes that threaten homeostasis;
– the presence of corrective devices that come into effect in a timely manner and delay the onset of these changes.

E. Pfluger, S. Riche, I.M. Sechenov, L. Frederick, D. Haldane and other researchers working at the turn of the 19th and 20th centuries also approached the idea of ​​the existence of physiological mechanisms that ensure the stability of the body and used their own terminology. However, the most widespread term among both physiologists and scientists of other specialties is homeostasis, proposed by W. Cannon to characterize the states and processes that create such an ability.

For biological sciences, in understanding homeostasis according to W. Cannon, it is valuable that living organisms are considered as open systems that have many connections with the environment. These connections are carried out through the respiratory and digestive organs, surface receptors, nervous and muscular systems, etc. Changes in the environment directly or indirectly affect these systems, causing corresponding changes in them. However, these effects are usually not accompanied by large deviations from the norm and do not cause serious disturbances in physiological processes.

Contribution of L.S. Stern in the development of ideas about homeostasis

Simultaneously with W. Cannon in 1929 in Russia, the Russian physiologist L.S. formulated her ideas about the mechanisms of maintaining the constancy of the internal environment. Stern. “Unlike the simplest, in more complex multicellular organisms, exchange with the environment occurs through the so-called medium, from which individual tissues and organs draw the material they need and into which they release the products of their metabolism. ... As individual parts of the body (organs and tissues) differentiate and develop, each organ and each tissue must have its own immediate nutrient medium, the composition and properties of which must correspond to the structural and functional characteristics of the given organ. This immediate nutritious, or intimate, environment must have a certain constancy, ensuring the normal functioning of the organ being washed. ... The immediate nutrient medium of individual organs and tissues is intercellular or tissue fluid.”

L.S. Stern established the importance for the normal functioning of organs and tissues of the constancy of the composition and properties of not only blood, but also tissue fluid. She showed existence of histohematological barriers– physiological barriers separating blood and tissues. These formations, in her opinion, consist of capillary endothelium, basement membrane, connective tissue, and cellular lipoprotein membranes. Selective permeability of barriers helps maintain homeostasis and the known specificity of the internal environment necessary for the normal function of a particular organ or tissue. Proposed and well-founded by L.S. Stern's theory of barrier mechanisms is fundamental new contribution into the doctrine of the internal environment.

Histohematic , or vascular tissue , barrier - this is, in essence, a physiological mechanism that determines the relative constancy of the composition and properties of the organ’s and cell’s own environment. It performs two important functions: regulatory and protective, i.e. ensures regulation of the composition and properties of the organ’s and cell’s own environment and protects it from the entry from the blood of substances foreign to the given organ or the entire organism.

Histohematic barriers are present in almost all organs and have corresponding names: blood-brain, hemato-ophthalmic, hematolabyrinthine, hematoliquor, hematolymphatic, hematopulmonary and hematopleural, hematorenal, as well as the “blood-gonads” barrier (for example, hematotesticular), etc.

Modern ideas about homeostasis

The idea of ​​homeostasis turned out to be very fruitful, and throughout the 20th century. it was developed by many domestic and foreign scientists. However, this concept is still biological science does not have a clear terminological definition. In scientific and educational literature one can find either equivalence of the terms “internal environment” and “homeostasis”, or different interpretations of the concept “homeostasis”.

Internal environment of the body call the entire set of circulating fluids of the body: blood, lymph, intercellular (tissue) fluid that washes cells and structural tissues, involved in metabolism, chemical and physical transformations. TO components The internal environment also includes intracellular fluid (cytosol), considering that it is directly the environment in which the main reactions of cellular metabolism take place. The volume of cytoplasm in the adult human body is about 30 liters, the intercellular fluid is about 10 liters, and the blood and lymph occupying the intravascular space is 4–5 liters.

In some cases, the term “homeostasis” is used to denote the constancy of the internal environment and the body’s ability to provide it. Homeostasis is a relative dynamic constancy of the internal environment, fluctuating within strictly defined boundaries, and the stability (stability) of the basic physiological functions of the body. In other cases, homeostasis is understood as physiological processes or control systems that regulate, coordinate and correct the vital functions of the body in order to maintain a stable state.

Thus, the definition of the concept of homeostasis is approached from two sides. On the one hand, homeostasis is considered as the quantitative and qualitative constancy of physicochemical and biological parameters. On the other hand, homeostasis is defined as a set of mechanisms that maintain the constancy of the internal environment of the body.

Analysis of definitions available in biological and reference books, made it possible to highlight the most important aspects of this concept and formulate a general definition: homeostasis is a state of relative dynamic equilibrium of the system, maintained through self-regulation mechanisms. This definition not only includes knowledge about the relativity of the constancy of the internal environment, but also demonstrates the importance of homeostatic mechanisms biological systems, ensuring this constancy.

TO vital functions The body includes homeostatic mechanisms of a very different nature and action: nervous, humoral-hormonal, barrier, controlling and ensuring the constancy of the internal environment and operating at different levels.

The principle of operation of homeostatic mechanisms

The principle of operation of homeostatic mechanisms that ensure regulation and self-regulation at different levels of organization of living matter was described by G.N. Kassil. The following levels of regulation are distinguished:

1) submolecular;
2) molecular;
3) subcellular;
4) cellular;
5) liquid (internal environment, humoral-hormonal-ionic relationships, barrier functions, immunity);
6) fabric;
7) nervous (central and peripheral nervous mechanisms, neurohumoral-hormonal-barrier complex);
8) organismic;
9) population (populations of cells, multicellular organisms).

The elementary homeostatic level of biological systems should be considered organismic. Within its boundaries, a number of others are distinguished: cytogenetic, somatic, ontogenetic and functional (physiological) homeostasis, somatic genostasis.

Cytogenetic homeostasis how morphological and functional adaptability expresses the continuous restructuring of organisms in accordance with the conditions of existence. Directly or indirectly, the functions of such a mechanism are performed by the cell's hereditary apparatus (genes).

Somatic homeostasis– the direction of the total shifts in the functional activity of the organism towards the establishment of its most optimal relationships with the environment.

Ontogenetic homeostasis- This individual development organism from the formation of the germ cell to death or cessation of existence in its former capacity.

Under functional homeostasis understand the optimal physiological activity of various organs, systems and the entire organism under specific environmental conditions. In turn, it includes: metabolic, respiratory, digestive, excretory, regulatory (providing an optimal level of neurohumoral regulation in given conditions) and psychological homeostasis.

Somatic genostasis represents control over the genetic constancy of the somatic cells that make up the individual organism.

We can distinguish circulatory, motor, sensory, psychomotor, psychological and even informational homeostasis, which ensures the body’s optimal response to incoming information. A separate pathological level is distinguished - diseases of homeostasis, i.e. disruption of homeostatic mechanisms and regulatory systems.

Hemostasis as an adaptive mechanism

Hemostasis is a vital complex of complex interconnected processes, integral part adaptive mechanism of the body. Due to the special role of blood in maintaining the basic parameters of the body, it is distinguished as an independent type of homeostatic reactions.

The main component of hemostasis is a complex system adaptive mechanisms that ensure the fluidity of blood in the vessels and its coagulation when their integrity is violated. However, hemostasis not only ensures the maintenance of the liquid state of blood in the vessels, the resistance of the vascular walls and stops bleeding, but also affects hemodynamics and vascular permeability, is involved in wound healing, in the development of inflammatory and immune reactions, and is related to the nonspecific resistance of the body.

The hemostatic system is in functional interaction with the immune system. These two systems form a single humoral defense mechanism, whose functions are connected, on the one hand, with the struggle for purity genetic code and prevention of various diseases, and on the other hand, maintaining the liquid state of blood in the circulatory system and stopping bleeding in case of violation of the integrity of blood vessels. Their functional activity is regulated by the nervous and endocrine systems.

The presence of common mechanisms for “switching on” the body’s defense systems – immune, coagulation, fibrinolytic, etc. – allows us to consider them as a single structurally and functionally defined system.

Its features are: 1) the cascade principle of sequential inclusion and activation of factors until the formation of the final physiological active substances: thrombin, plasmin, kinins; 2) the possibility of activating these systems in any part of the vascular bed; 3) general mechanism turning on systems; 4) feedback in the mechanism of interaction of these systems; 5) the existence of common inhibitors.

Ensuring the reliable functioning of the hemostasis system, like other biological systems, is carried out in accordance with the general principle of reliability. This means that the reliability of the system is achieved by the redundancy of control elements and their dynamic interaction, duplication of functions or interchangeability of control elements with a perfect quick return to the previous state, the ability for dynamic self-organization and the search for stable states.

Circulation of fluid between cellular and tissue spaces, as well as blood and lymphatic vessels

Cellular homeostasis

The most important place in self-regulation and preservation of homeostasis is occupied by cellular homeostasis. It is also called cell autoregulation.

Neither the hormonal nor the nervous systems are fundamentally capable of coping with the task of maintaining the constancy of the composition of the cytoplasm of an individual cell. Each cell of a multicellular organism has its own mechanism for autoregulation of processes in the cytoplasm.

The leading place in this regulation belongs to the outer cytoplasmic membrane. It ensures the transmission of chemical signals into and out of the cell, changing its permeability, takes part in the regulation of the electrolyte composition of the cell, and performs the function of biological “pumps”.

Homeostats and technical models of homeostatic processes

In recent decades, the problem of homeostasis began to be considered from the perspective of cybernetics - the science of targeted and optimal control of complex processes. Biological systems, such as a cell, brain, organism, population, ecosystems function according to the same laws.

The founder of the theory of control in living objects is N. Wiener. His ideas are based on the principle of self-regulation - automatic maintenance of constancy or change according to the required law of the regulated parameter. However, long before N. Wiener and W. Cannon, the idea of ​​automatic control was expressed by I.M. Sechenov: “...in the animal body, regulators can only be automatic, i.e. be brought into action by altered conditions in the state or progress of the machine (organism) and develop activities by which these irregularities are eliminated.” This phrase indicates the need for both direct and feedback connections that underlie self-regulation.

The idea of ​​self-regulation in biological systems was deepened and developed by L. Bertalanffy, who understood a biological system as “an ordered set of interconnected elements.” He also considered the general biophysical mechanism of homeostasis in the context of open systems. Based on the theoretical ideas of L. Bertalanffy, a new direction has emerged in biology, called systems approach. The views of L. Bertalanffy were shared by V.N. Novoseltsev, who presented the problem of homeostasis as a problem of controlling the flows of substances and energy that open system exchanges with the environment.

The first attempt to model homeostasis and establish possible control mechanisms was made by U.R. Ashby. He designed an artificial self-regulating device called a “homeostat”. Homeostat U.R. Ashby represented a system of potentiometric circuits and reproduced only the functional aspects of the phenomenon. This model could not adequately reflect the essence of the processes underlying homeostasis.

The next step in the development of homeostatics was made by S. Beer, who pointed out two new fundamental points: the hierarchical principle of constructing homeostatic systems for controlling complex objects and the principle of survivability. S. Beer tried to apply certain homeostatic principles in the practical development of organized control systems and identified some cybernetic analogies between a living system and complex production.

Qualitatively new stage The development of this direction began after the creation of a formal homeostatic model by Yu.M. Gorsky. His views were formed under the influence of the scientific ideas of G. Selye, who argued that “... if it is possible to include contradictions in models reflecting the work of living systems, and at the same time understand why nature, when creating living things, took this path, this will be a new breakthrough into the secrets of the living with great practical results.”

Physiological homeostasis

Physiological homeostasis is maintained by the autonomic and somatic nervous system, a complex of humoral-hormonal and ionic mechanisms that make up the physico-chemical system of the body, as well as behavior, in which the role of both hereditary forms and acquired individual experience is significant.

The idea of ​​the leading role of the autonomic nervous system, especially its sympathoadrenal department, was developed in the works of E. Gelgorn, B.R. Hess, W. Cannon, L.A. Orbeli, A.G. Ginetsinsky and others. The organizing role of the nervous apparatus (the principle of nervism) underlies the Russian physiological school of I.P. Pavlova, I.M. Sechenova, A.D. Speransky.

Humoral-hormonal theories (the principle of humoralism) were developed abroad in the works of G. Dale, O. Levy, G. Selye, C. Sherrington and others. Russian scientists I.P. paid much attention to this problem. Razenkov and L.S. Stern.

The accumulated colossal factual material describing various manifestations of homeostasis in living, technical, social, ecological systems, requires study and consideration from a unified methodological perspective. The unifying theory that was able to connect all the diverse approaches to understanding the mechanisms and manifestations of homeostasis became functional systems theory, created by P.K. Anokhin. In his views, the scientist was based on N. Wiener’s ideas about self-organizing systems.

Modern scientific knowledge about the homeostasis of the whole organism is based on understanding it as a friendly and coordinated self-regulating activity of various functional systems, characterized by quantitative and qualitative changes in their parameters during physiological, physical and chemical processes.

The mechanism for maintaining homeostasis resembles a pendulum (scales). First of all, the cytoplasm of the cell must have a constant composition - homeostasis of the 1st stage (see diagram). This is ensured by the mechanisms of homeostasis of the 2nd stage - circulating fluids, the internal environment. In turn, their homeostasis is associated with vegetative systems for stabilizing the composition of incoming substances, liquids and gases and the release of final metabolic products - stage 3. Thus, temperature, water content and concentrations of electrolytes, oxygen and carbon dioxide, and the amount of nutrients are maintained at a relatively constant level and excreted metabolic products.

The fourth stage of maintaining homeostasis is behavior. In addition to appropriate reactions, it includes emotions, motivation, memory, and thinking. The fourth stage actively interacts with the previous one, builds on it and influences it. In animals, behavior is expressed in the choice of food, feeding grounds, nesting sites, daily and seasonal migrations, etc., the essence of which is the desire for peace, the restoration of disturbed balance.

So, homeostasis is:

1) the state of the internal environment and its properties;
2) a set of reactions and processes that maintain the constancy of the internal environment;
3) the body’s ability to withstand environmental changes;
4) the condition of existence, freedom and independence of life: “The constancy of the internal environment is a condition free life"(C. Bernard).

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  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.

  Properties of homeostasis

  Homeostatic systems have the following properties:

  • Instability system: testing how best to adapt.
  • Striving for balance: all internal, structural and functional organization systems helps maintain balance.
  • Unpredictability: The resulting effect of a certain action can often be different from what was expected.
  • Regulation of the amount of micronutrients 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 and gastrointestinal tract.
  • 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.
  • Regulation of the level of basal metabolism depending on the diet.

  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 in variables occurs, there are two main types of feedback to which the system responds:

  1. Negative feedback, expressed in 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 of carbon dioxide in the human body increases, 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 (or increase).
  2. Positive feedback, which is expressed in increasing the change in a variable. It has a destabilizing effect and therefore does not lead to homeostasis. Positive feedback is less common in natural systems, but also has its uses.
     • For example, in nerves, a threshold electrical potential causes the generation of a much larger action potential. Blood clotting and 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 (algae overgrowing of the riverbed) and turbidity.

  Ecological homeostasis

  In disturbed ecosystems, or subclimax biological communities - such as the island of Krakatoa, after a large volcanic eruption - 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 took place in several stages. The complete chain of successions leading to climax is called preseria. In the Krakatoa example, the island developed a climax community with eight thousand different species recorded in , one 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). When an ecosystem approaches climax, such species are replaced by more complex climax species, which, 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 - producing fewer offspring, the reproductive success of which is invested more energy in the microenvironment of its specific ecological niche.

  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 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 permanent shift trees, nutrient cycle carried out by bacteria, insects, fungi. Similarly, such forests contribute to ecological processes such as the regulation of microclimates or hydrological cycles of an 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

  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, whereas 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 spend a lot less energy to maintain homeostasis than mammals.

  Cellular homeostasis

  Regulation of the chemical activity of the cell is achieved through a number of processes, including special meaning has a change in the structure of the cytoplasm itself, as well as the structure and activity of enzymes. Autoregulation depends on

  Homeostasis is the ability of the human body to adapt to changing conditions of the external and internal environment. The stable operation of homeostasis processes guarantees a person a comfortable state of health in any situation, maintaining the constancy of the body’s vital indicators.

  Homeostasis from a biological and ecological point of view

  Homeostasis applies 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 also undergoes changes and is constantly rebuilt for continued 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.

  Humans are no exception; homeostatic mechanisms play a vital 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 failure in homeostasis can lead to fatal consequences.

  Why is homeostasis needed and its types?

  Every day a person is exposed to various environmental factors, but in order for the main biological processes in the body continued to work stably, their conditions should 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 combination; if one of them fails, this leads to unpleasant consequences for good health. Coordinated work of processes will allow you not to notice 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 with each other, while maintaining the balance and uniformity of a conditionally closed group of people (population).

  Physiological homeostasis

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

  • Body temperatures.
  • 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 entire body, leading to weakening protective functions and the development of diseases.

  Cellular homeostasis (structural)

  

  This type is also called "regenerative", 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, when working properly, that allow the body to recover from illness or injury.

  The basic mechanisms of homeostasis develop and evolve along 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 using specific examples.

  For example, when playing sports, human breathing and heart rate increase, which indicates the body’s desire to maintain internal balance under changed environmental conditions.

  When moving to a country with a climate significantly different from your usual one, you may feel unwell for some time. Depending on the general health human, homeostasis mechanisms allow adaptation to new living conditions. Some people do not feel acclimatization and the internal balance quickly adjusts, while others have to wait a little before the body adjusts its parameters.

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

  

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

  Based on the examples given, the main functions can be clearly seen:

  • Energy.
  • Adaptive.
  • Reproductive.

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

  Properties of homeostasis

  Knowing about the main 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.

  The mechanisms are in constant change, testing conditions in order to choose the best option for adapting to them. This shows 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 body's reaction to changes in the external or internal environment may become unexpected and 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 a medical point of view, any disease is evidence of a malfunction in homeostasis. External and internal threats constantly impact the body, and only coherence in the operation of the main systems will help cope with them.

  Weakening of the immune system does not occur without 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 homeostasis functions to work correctly and as quickly as possible, it is necessary to monitor general condition your health. To do this, you can consult a doctor for an examination to determine your vulnerabilities and choose a complex of therapy to eliminate them. Regular diagnostics will help to better control the basic processes of life.

  

  It is important to follow these simple recommendations yourself:

  • Avoid stressful situations to protect nervous system from constant overvoltage.
  • Monitor your diet, do not overload yourself with heavy foods, and avoid pointless fasting, which will allow you to digestive system It's easier to do your job.
  • Choose appropriate vitamin complexes to reduce the impact of seasonal weather changes.

  A vigilant attitude towards your own health will help homeostatic processes respond promptly and correctly to any changes.

  The existence of an organism depends on the preservation of certain parameters. If the brain temperature changes by a few degrees, the person will lose consciousness. If the amount of water in the body changes by a few percent, the brain and body will not be able to function, and the person may die. Human bodies, like all animals, are constantly balancing between different physiological extremes.

  However, nature has laid down a mechanism for maintaining physical and physiological balance. This mechanism is quite complex. The desired ideal state is usually called homeostasis (from the ancient Greek “homeo” and “stasis” - “equal” and “constant”). The mechanisms involved in maintaining this constant state, homeostasis, are called homeostatic. Maintaining homeostasis can be:

  Mechanical

  Physiological,

  Conscious.

  An example of homeostatic mechanisms is sweating or shaking. In the first case, the body is cooled by wetting the skin and receiving cooling due to evaporated water. In the second case, additional mechanical energy is produced, which is transformed according to physical laws into thermal energy, which leads to an increase in body temperature (warming).

  The triggering of the sweating mechanism or, conversely, the trembling mechanism begins with signals produced by specialized neurons located in the preoptic (anterior) region of the hypothalamus at the base of the brain. These neurons are essentially biological sensors. When their own temperature changes, they begin to work differently, the nature of their activity changes, thereby sending signals along the chain to other neurons. One effect of this is sweating or shaking. Another effect will be a conscious sensation of cold or heat, which may prompt you to get into a warm bath or finally take off your fur coat.

  As the parameters return to the ideal state, the intensity of the sensations decreases, until they cease completely. It is interesting to note that in a state of homeostasis, sensations disappear. The information that everything is normal comes precisely from the absence of unpleasant sensations. There is a special sensation for "hot" or "cold", but there is no special sensation for normal temperature.

  It is also interesting that long absence some unpleasant sensations (a state of homeostasis) in itself can be perceived as uncomfortable, a person begins to feel the need for a shake-up (at least lightly): he can put on sneakers and go for a run, go to an action-packed movie, take some dangerous event, go to a nightclub.

  Experiments have shown that the brain can be tricked into feeling hot or cold simply by changing the temperature of some neurons in the hypothalamus. The heating or cooling of these neurons causes the entire body to sweat or tremble.

  Body temperature is just one example of homeostatic mechanisms at work. For other physical and physiological parameters, there is similar self-regulation. However, if in the case of temperature, the body has its own means to maintain homeostasis (sweating, trembling), then in some other cases the sanction of consciousness is required for certain necessary actions.

  Water gradually leaves the body: it is eliminated through urination, skin, and breathing. There is quite a lot of water in the body. This is water contained in the cells of the body, and water located outside the cells (blood, other liquid media). But even with a slight loss of water, a feeling of thirst already arises. There are receptor sensors in the body that closely monitor blood pressure and the percentage of salts in the blood. When receptors detect decline blood pressure, combined with an increase in the proportion of salts in the blood, a number of signals also begin to spread along the chain: receptors - hypothalamus - pituitary gland. The pituitary gland releases antidiuretic hormone (ADH) into the bloodstream. This hormone causes the kidneys to retain water in the blood as it filters it. The brain also directly sends a nerve signal to the kidneys to release its own hormone, renin, which chemically reacts with a substance in the blood to produce another hormone, angiotensin. Angiotensin travels through the bloodstream to neurons located deep in the brain, which already cause a conscious desire to drink.

  Allocation of ADH is only a measure of water conservation; it cannot return ideal parameters. Because for this you need to drink water. And in order to drink, the work of consciousness is necessary to plan and implement this act (get up from the chair - go to the kitchen to put the kettle on - wait a while - brew tea - wait a while - throw away the bag - add sugar - drink). If the body had the right to drink water without the intervention of consciousness, then one would see unpleasant scenes on the street, as people for no apparent reason jump up to puddles and drink water from them like stray dogs. However, it is worth noting that in a state of severe frustration in some parameter (including water), a person is really capable of unconscious (or poorly conscious) actions that he is not capable of in a normal state. Thus, we see that human consciousness is also actively involved in maintaining homeostasis.

  Literature

  Atkinson R. L., Atkinson R. S., Smith E. E. et al. Introduction to psychology: Textbook for universities / Transl. from English under. ed. V. P. Zinchenko. - M.: Trivola, 1999.