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

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

  properties of homeostasis

  Homeostatic systems have the following properties:

  • instability system: tests how it can best adapt.
  • Striving for balance: all the internal, structural and functional organization of systems contributes to maintaining balance.
  • unpredictability: The resultant effect of a certain action can often be different from what was expected.
  • Regulation of the amount of micronutrients and water in the body - osmoregulation. Carried out in the kidneys.
  • Removal of waste products of the metabolic process - isolation. It is carried out by exocrine organs - kidneys, lungs, sweat glands and gastrointestinal tract.
  • Body temperature regulation. Lowering the temperature through sweating, a variety of thermoregulatory reactions.
  • Regulation of blood glucose levels. It is mainly carried out by the liver, insulin and glucagon secreted by the pancreas.
  • Regulation of the level of basic metabolism depending on the diet.

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

  Mechanisms of homeostasis: feedback

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

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

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

  Ecological homeostasis

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

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

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

  Biological homeostasis

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

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

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

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

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

  Cellular homeostasis

  Regulation of the chemical activity of the cell is achieved through a number of processes, among which the change in the structure of the cytoplasm itself, as well as the structure and activity of enzymes, is of particular importance. Autoregulation depends on

  The term "homeostasis" comes from the word "homeostasis", which means "strength of stability". Many rarely hear, if not at all, about this concept. However, homeostasis is an important part of our life, harmonizing contradictory conditions among themselves. And this is not just a part of our life, homeostasis is an important function of our body.

  If we define the word homeostasis, the meaning of which is to regulate the most important systems, then this is the ability to coordinate various reactions, allowing you to maintain balance. This concept is applicable both to individual organisms and to entire systems.

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

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

  • Instability. At this moment, we, namely our inner self, diagnose the changes and, based on this, make a decision to adapt to new circumstances.
  • Equilibrium. All our internal forces are aimed at maintaining balance.
  • Unpredictability. Often we can surprise ourselves by taking some action that we did not expect.

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

  Unexpected decisions

  Homeostasis has taken a firm place not only in biology. This term is actively used in psychology. In psychology, the concept of homeostasis implies our attitude towards external conditions.. Nevertheless, this process closely links the adaptation of the organism and individual mental adaptation.

  Everything in this world strives for balance and harmony, just as individual relationships with the environment tend to harmonize. And this happens not only on the physical level, but also on the mental level. An example can be given: a person laughs, but then he was told a very sad story, laughter is already inappropriate. The body and emotional system are brought into action by homeostasis, calling for the right response - and your laughter is replaced by tears.

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

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

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

  Imagine the situation: a group of fallow deer is grazing near a sleeping lion. Suddenly the lion wakes up and roars, the fallow deer rush in all directions. Now imagine yourself in the place of a doe. The instinct of self-preservation worked in her - she ran away. She must run very fast to save her life. This is psychological homeostasis.

  But some time of running passes, and the deer begins to run out of steam. Even though a lion may be chasing her, she will stop, because the need to breathe at the moment turned out to be more important than the need to run. This is an instinct of the organism itself, physiological homeostasis. Thus, the following types of homeostasis can be distinguished:

  • Forcing.
  • Spontaneous.

  The fact that the doe rushed to run is a spontaneous psychological urge. She must survive, and she ran. And the fact that she stopped to catch her breath is a compulsion. The organism forced the animal to stop, otherwise life processes could be disturbed.

  The value of homeostasis is very important for any organism, both psychologically and physically. A person can learn to live in harmony with himself and the environment, not only following the urges of instincts. He only needs to correctly see and understand the world around him, as well as sort out his thoughts, setting priorities in the right order. Author: Lyudmila Mukhacheva

  Homeostasis, homeostasis (homeostasis; Greek homoios similar, the same + stasis state, immobility), is the relative dynamic constancy of the internal environment (blood, lymph, tissue fluid) and the stability of basic physiological functions (blood circulation, respiration, thermoregulation, metabolism and etc.) of the human and animal organisms. 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 you know, a living cell is a mobile, self-regulating system. Its internal organization is supported by active processes aimed at limiting, preventing or eliminating shifts caused by various influences from the environment and the internal environment. The ability to return to the original state after a deviation from a certain average level, caused by one or another "disturbing" factor, is the main property of the cell. A multicellular organism is a holistic organization, the cellular elements of which are specialized to perform various functions. Interaction within the body is carried out by complex regulatory, coordinating and correlating mechanisms with

  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 concept of homeostasis does not correspond to the concept of a stable (non-fluctuating) balance in the body - the principle of balance is not applicable to

  complex physiological and biochemical

  processes 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.

  Despite the fact that blood represents the general internal environment of the body, the cells of organs and tissues do not directly come into contact with it.

  In multicellular organisms, each organ has its own internal environment (microenvironment) corresponding to its structural and functional features, and the normal state of organs depends on the chemical composition, physicochemical, biological and other properties of this microenvironment. Its homeostasis is determined by the functional state of histohematic barriers and their permeability in the directions of blood→tissue fluid, tissue fluid→blood.

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

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

  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.

  The control of body temperature in humans is considered an excellent example of homeostasis in a 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 specific 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 keeps 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 of the chemical reactions that keep cells alive and functioning. 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 to produce more urine.

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  The internal environment of the body- a set of body fluids that are inside it, as a rule, in certain reservoirs and natural conditions and never come into contact with the external environment. The term was proposed by the French physiologist Claude Bernard.
  Cells can only function in a liquid medium. Blood, tissue fluid and lymph form the internal environment of the body. The basis of the internal environment of the body is the blood, which delivers oxygen and nutrients to cells and removes metabolic products. However, the blood does not directly come into contact with the cells of the body. In tissues, part of the blood plasma leaves the blood capillaries and turns into tissue fluid. Excess tissue fluid is absorbed by the lymphatic capillaries and in the form of lymph flows through the lymphatic vessels back into the blood. Thus, blood, tissue fluid and lymph directly circulate within the body, ensuring the exchange of substances between body cells and the environment. Scientists from many countries of the world tried to find out the nature of the mechanisms that maintain the constancy of the internal environment of humans and higher animals.

  The set of factors and mechanisms that ensure this constancy is called homeostasis. homeostasis- the ability of biological systems to resist changes and maintain the dynamic constancy of the composition and properties of the organism.

  Homeostasis is a relatively dynamic constancy of the internal environment of the body, ensuring the stability of its basic physiological functions.

  Claude Bernard (1878) - formulation of the concept of homeostasis.

  Walter Cannon coined the term homeostasis, his hypothesis is individual parts of the organism are stable, since the internal environment surrounding them is stable.

  Living organism- an open self-regulating system that develops in close interaction with the environment. Changes in the environment directly or indirectly affect the components, causing them to change accordingly.

  Due to the mechanisms of self-regulation, these changes occur within the limits of the normal reaction and do not cause serious violations of physiological functions.

  Violation of regulatory mechanisms leads to a breakdown of the body's compensatory capabilities, a decrease in its resistance to constantly changing environmental conditions, violations of homeostasis conditions and the development of pathologies.

  The mechanisms of homeostasis should be aimed at maintaining the level of a steady state, coordinating processes to eliminate or limit the influence of harmful factors, optimal interaction between the organism and the environment in the changed conditions of existence.

  Components of homeostasis:

   Components that provide cellular needs: proteins fats carbohydrates; inorganic substances; water, oxygen, internal secretion.

  
  
  

   Components affecting cellular activity: osmotic pressure, temperature, concentration of hydrogen ions.

  Types of homeostasis:

   Genetic homeostasis . The genotype of the zygote, when interacting with environmental factors, determines the whole complex of variability of the organism, its adaptive ability, that is, homeostasis. The organism reacts to changes in environmental conditions specifically, within the limits of the hereditarily determined norm of reaction. The constancy of genetic homeostasis is maintained on the basis of matrix syntheses, and the stability of the genetic material is ensured by a number of mechanisms (see mutagenesis).

   structural homeostasis. Maintaining the constancy of the composition and integrity of the morphological organization of cells and tissues. The multifunctionality of cells increases the compactness and reliability of the entire system, increasing its potential. The formation of cell functions occurs due to regeneration.

  Regeneration:

  1. Cellular (direct and indirect division)

  2. Intracellular (molecular, intraorganoid, organoid)

   Physico-chemical homeostasis.

  Gas homeostasis: the concentration of oxygen and carbon dioxide in the body, provided by the external respiration system. Factors regulating external respiration: minute volume of respiration of alveolar air, envy from the activity of the respiratory center; the content of gases in the blood and pulmonary capillaries; diffusion of gases through the membrane of blood cells, uniform pulmonary blood flow adequate ventilation.

  Acid-base balance of the body: blood pH = 7.32-7.45 The ratio of hydrogen and hydroxide ions depends on the content of acids, which act as proton donors, and amphoteric bases, which are acceptors. Its regulation is provided by buffer systems, tissue proteins, collagen substance of the connective tissue, which is able to adsorb acids.

  Osmotic properties of blood: The osmotic pressure of blood depends on the concentration of the solution and temperature, but does not depend on the nature of the solute and solvent. The constancy of the osmotic properties of blood is ensured by the water balance. The body's water balance is maintained by the mechanisms of water and salt intake. Redistribution of water and salts between cells and intracellular organelles, release of water and salts into the environment. The basis for the integration of the entire physicochemical homeostasis is neuroendocrine regulation.

   physiological homeostasis.

  Thermal homeostasis: maintenance of heat content. An important condition for thermal balance is the movement of the medium surrounding the body and its parts, in which heat exchange occurs, the regulation of thermal insulation is ensured by the influx of warm blood from deep areas of the body to its surface.

  Hemostasis system: activation of the blood coagulation system, the required level of blood cells, restoration of the properties of the vessel wall.

  Biochemical homeostasis: maintenance at the level of metabolic processes, in particular anabolism and catabolism, the balance of synthesis and decay processes is carried out by changing the activity of enzymes, the rate of enzymatic reactions, inducing the biosynthesis of proteins and enzymes and regulating the rate of decay of biologically active substances.

   immunological homeostasis.

  The immune system protects the body from exogenous substances, infectious agents that carry genetically alien information, as well as from pathologically altered cells. Recognition - destruction - elimination. The central organs of the immune system are the bone marrow and thymus. Peripheral organs - spleen and lymphoid tissue. The bone marrow produces an antibody stimulator that activates the B-lymphocyte system that provides the humoral link of immunity, and the thymus produces thymosin, which activates the production of T-lymphocytes. Maintenance of immunological homeostasis should be ensured by the necessary concentration of T- and B-lymphocytes.

  Endocrine homeostasis: synthesis and secretion of hormones, transport of hormones, specific metabolism of hormones in the periphery and their excretion, interaction of hormones with target cells, regulation and self-regulation of the functions of endocrine glands.

  All homeostasis as a whole are biological homeostasis , an integral system of various functions and indicators that ensure the preservation and maintenance of the normal life of the organism in changing environmental conditions.

  Regulation of biological homeostasis:

  local: is carried out through positive and negative feedbacks, when a change in one indicator leads to a change in another, is characterized by autonomy, this property is inherent in any component of a living system.

  Humoral regulation , associated with the entry into the internal environment of the body of humoral factors - mediators, hormones, biologically active substances, etc. the humoral system reacts to external influences slowly, because has no connection with the environment, but gives a more stable and lasting effect, provided by the endocrine glands. On the basis of humoral regulation, adaptive reactions to changes in the internal environment of the body develop.

  Nervous regulation: the main coordinator of all biological processes, which is due to the structural and functional features of the nervous system: presence in all organs and tissues, direct contact with the external environment through receptors, high excitability, lability and precise direction of nerve impulses and high speed of information transmission. The regulation of adaptive reactions is based on reflex processes. Nervous regulation provides a change in the functional activity of organs or functions in response to external influences and adaptation of the body with the external environment.

  Levels of neuroendocrine regulation:

  1. Cell membrane

  2. Endocrine glands

  3. Pituitary gland

  4. Hypothalamus

  The inclusion of various levels of neurohumoral regulation is determined by the intensity of the influence of the factor, the degree of deviation of physiological parameters and the lability of adaptive systems.

  Question 54.