Adaptation begins to develop against the background of a generalized orienting reaction, activation of a nonspecific, as well as a specific response to a causal factor. Subsequently, temporary and functional systems are formed that provide the body with either “escape” from the acting emergency agent, or overcoming its pathogenic effects, or an optimal level of vital activity, despite the continuing influence of this agent, i.e. adaptation itself.

Emergency adaptation phase (alarm) consists in the mobilization of compensatory, protective and adaptive mechanisms. This is manifested by a triad of natural changes - activation, hyperfunction, mobilization.

- Activation of "research" behavioral activity of the individual, aimed at obtaining maximum information about the emergency factor and the possible consequences of its action.

- Hyperfunction of many body systems, but mainly those that directly (specifically) provide adaptation to this factor. These systems (physiological and functional) are called dominant.

- Mobilization of organs and physiological systems(cardiovascular, respiratory, blood, immunobiological surveillance systems, metabolism, etc.), which react to the effects of any factor that is extraordinary for a given organism.

The development of the emergency phase of adaptation is based on there are several interrelated mechanisms, the launch of which is carried out as a result of activation under the action of an extraordinary factor of the autonomic nervous (sympathetic section) and endocrine systems and, as a consequence, a significant increase in the blood and other body fluids of the so-called stress hormones that activate the function and catabolic processes of hormones and neurotransmitters - adrenaline , norepinephrine, glucagon, gluco- and mineralocorticoids, thyroid hormones.

The biological meaning of reactions developing in the emergency phase of adaptation (despite their non-specificity, imperfection, high energy and substrate "cost") is to create the conditions necessary for the organism to "hold out" until the stage of formation of its stable adaptation (resistance) to the action of an extreme factor.

Transitional phase of adaptation characterized by a decrease in the excitability of the central nervous system, the formation of functional systems that provide control of adaptation to new conditions. The intensity of hormonal changes decreases, a number of systems and organs that were initially involved in the reaction are gradually turned off. During this phase, the body's adaptive reactions are gradually switched to a deeper - tissue - level. The hormonal background changes, the hormones of the adrenal cortex - "hormones of adaptation", increase their effect.

Stage of stable, or long-term adaptation of the body to the action of the extraordinary factor is implemented as follows. Happened:

Formation of a state of specific resistance of the organism both to a specific agent that caused the adaptation, and often to other factors - cross-adaptation;

An increase in the power and reliability of the functions of organs and dominant physiological systems that ensure adaptation to a certain factor. In such systems, there is an increase in the number and / or mass of structural elements (i.e. hypertrophy and hyperplasia), endocrine glands, effector tissues and organs.

The complex of such changes is designated as the structural trace of the adaptation process. Signs of a stress reaction are eliminated, an effective adaptation of the body to an emergency factor that caused the adaptation process is formed. As a result, a reliable and stable adaptation of the organism to the changing socio-biological conditions of the environment is formed. Processes both activated earlier and additionally included are implemented. The latter include reactions that provide the predominant energy and plastic supply of the cells of the dominant systems. This is combined with limiting the supply of oxygen and metabolic substrates of other body systems and is carried out through reactions of two categories:

Redistribution of blood flow - an increase in it in the tissues and organs of the dominant systems due to a decrease in others;

Activation of the genetic apparatus of long-term hyperfunctioning cells and subsequent hypertrophy and hyperplasia of subcellular structural elements with simultaneous inhibition of gene expression in cells of non-dominant systems and organs (for example, digestion, muscular system, kidneys, etc.).

Disadaptation. In most cases, the adaptation process ends with the formation of long-term resistance of the organism to the emergency factor acting on it. And at the same time, the phase of persistent adaptation is associated with constant tension of the governing and executive structures, which can lead to their depletion. Depletion of control mechanisms, on the one hand, and cellular mechanisms associated with increased energy costs, on the other hand, leads to maladjustment.

Incomplete adaptation occurs when the functional reserves of the body are depleted and includes the centralization of control and an increase in the reactivity of the mechanisms of autonomic regulation. The state of incomplete adaptation is characteristic not only of a significant part of people living in extreme climatic and geographic conditions, expeditionary shift workers, but also of a part of the population of megalopolises of the middle climatic zone, the ecological situation in which is unfavorable.

Let's turn to consideration psychological mechanisms adaptation. The mechanisms of adaptation, from the point of view of Yu. A. Aleksandrovsky, are determined from two points of view: 1) mechanisms of information processing, which are characterized as unconscious protective and 2) adaptive mechanisms, characterized as conscious purposeful. In connection with the concept of adaptation, characterized as a mechanism of a psychological nature, one can also consider the formation of a certain type of attitude towards the requirements of the situation. The types of relationships can have the character of meaningful, formal, indifferent, negative, while under the meaningful character we mean the attitude to the inner essence of the process, under formal - a set of external qualities and attributes, under indifferent - the absence of any signs and characteristics, under negative - negative attitude to the adaptation component.

Adaptation is associated with the emergence of a defense mechanism. Often, a person is not able to immediately accept and realize the ongoing changes in the environment; it takes time and awareness of the necessity or inevitability of changes to become aware. Necessity and inevitability in this case should not be perceived as fatal, but should be perceived as a given, therefore, the impossibility of changing this given leads to the construction of defense mechanisms.

For the first time, the founder of psychoanalysis, Z. Freud, began to study subjective methods of protection against unpleasant thoughts and threatening assessments. The scientist believed that in the course of development, a person develops defense mechanisms to protect against internal stimuli associated or not associated with the situation that has arisen. According to the researcher, one of the main problems of humanity is the problem of overcoming fear and anxiety that arise in a variety of situations.

Z. Freud in his work "Introduction to Psychoanalysis" defined psychological defense as a set of mechanisms that, being the results of development and learning, weaken the external and internal conflict and regulate the behavior of the individual. Z. Freud associated protection with the following functions of the psyche: balancing, adaptation and regulation. Purpose and purpose of various psychological defense mechanisms consists in the weakening of various components of the intrapersonal conflict, which include tension and anxiety, which arose as a contradiction between the instinctive, unconscious, and learned or internalized, related to the external environment, arising as a result of the interaction of the individual in society. Psychological defense, weakening the specified conflict, performs a regulatory function of human behavior, contributing to an increase in the level of adaptability and balance of the psyche.

A follower of this theory, A. Freud noted that typical children's defensive reactions to the influence of the environment can be considered reactions of refusal, opposition, imitation, compensation and emancipation. If refusal presupposes a passive reaction, such as rejection of food, food, refusal to play and communicate, then opposition is an active form of protest and is realized in the form of outbursts of anger, destructive actions, aggression, motor excitement, and deliberate harm to the offender. There are two types of imitations: positive and negative. The child borrows an example for imitation from the environment, which makes this type of defense as imitative and passive as possible.

Compensation as a reaction is associated with the fact that the child emphasizes his positive qualities in order to overcome the negative ones. Finally, emancipation is expressed in the desire to be or appear to be an adult, which is typical, for example, in the case of overprotection of a child.

Psychological adaptation depends on a number of factors, some of which are variable. Variable factors can be defined as individual characteristics, psychological defense mechanisms and strategies that are consciously used by a person in order to cope with difficult situations, states and conditions that give rise to them. A significant role in the process of psychological adaptation is assigned to the requirements of the social environment.

Depending on the disorders of early development and the characteristics of the assimilation of previous experience, as well as in the presence of current stressful events, we can talk about the severity of the individual's maladjustment. Disadaptation can occur due to various reasons, but as a phenomenon opposite to adaptation, it depends on the state nervous system and its ability to regulate the processes of inhibition and excitation. So, as a rule, the end of the depletion of physiological resources of regulation and a decrease in the adaptive properties of the nervous system experienced by the body long-term emotional stress, the lack of opportunities for rest and the impossibility of emotional and psychological recovery. The level of maladjustment, as well as the level of adaptation, is influenced by such basic innate abilities of a person as temperament, instincts, emotions and intellectual abilities. They form the basis of adaptability.

A special place in the issues of psychological adaptation is occupied by the problem of the social buffer. The social buffer refers to the resources and opportunities provided by the social environment that the individual uses to adapt. The social buffer is significant as a tool and as a means of personality adaptation. As a means of realizing a person's communicative abilities, social resources open up access to additional personal resources and significantly increase the adaptive potential of a person.

An important point in the process of psychological adaptation is the ability to try on and change your social roles. The effectiveness of adaptation depends not only on the number of roles used, but also on the justification and adequacy of their choice. Therefore, one of the criteria for psychological adaptation is a person's ability to critically assess their place in social group, their real capabilities and abilities. So, in one situation, the adaptant can behave like a leader, as a dominant person, in another situation, as a subordinate subject. This is particularly evident in the situation of adaptation in the classroom: the subject of adaptation cannot be a leader in relations with a teacher, but can be a leader in relations with classmates.

Often used in psychology, the term "adaptation syndrome" refers to a set of features that accompany the adaptation process. In the course of the syndrome, three stages are distinguished: the stage of anxiety, the stage of resistance, the stage of stabilization of the state, or exhaustion. The stage of anxiety is characteristic of the initial period of adaptation and is associated with the emergence of an individual's fears of the unknown, in particular, of the environment into which it enters, of communication partners. The stage of resistance is viewed as a process of rejection of the conditions of the new environment, the conditions of the new team. At this stage, internal obstacles arise that do not allow the individual to unconditionally accept the new conditions. This stage ends either with the stabilization of the state - the adaptation syndrome develops into the normalization of the adaptation process, or leads the person to a stage of exhaustion, when the changes are not accepted internally, do not suit the person, she is not ready to accept them emotionally and feels discomfort from being in this environmental situation.

Psychological adaptation is a concept that underlies the concept of human health, since the conclusion "mental disorder" is not based on the subjective opinion of a doctor, but on objective signs of a person's low adaptive ability. Problematic situations arising in the process of socialization become a trigger for starting adaptation processes.

The need for behavior correction arises in cases of tension in the adaptive capabilities of the individual. The presence of well-coordinated compensatory abilities allows a person to be classified as healthy. A.A. Nalchadzhian addressed the issue of adaptation mechanisms in their works. in the works "Personality, group socialization and mental adaptation" and "Socio-psychological adaptation of personality", Berezin F.B. in the study "Mental and psychophysiological adaptation of a person." These authors consider the adaptation mechanism as a certain structure, which includes a number of levels: psychophysiological level of adaptation, psychological level of adaptation and social level of adaptation.

The first type of adaptation is defined as a set of physiological reactions of the body. This type of adaptation cannot be considered separately from the mental and personal components, since this type of adaptation cannot exist on its own: a person is a social being, and not just a physiological one. The second type of adaptation (psychological) is the ability to maintain integrity and adequately respond to various environmental situations. According to F.B. Berezina, A.A. Nalchajyan and others, it is mental adaptation that provides the most important connections between a person and the environment. The effectiveness of mental adaptation is assessed taking into account its psychophysiological and socio-psychological value, which is determined by energy and information costs.

Social adaptation is the process of adaptation of a person to society. All levels of adaptation are simultaneously and to varying degrees involved in the regulatory process.

In the process of psychological adaptation, both the personality and the environment are actively changing, as a result of which relations of adaptation are established between them. M. Velichko identifies several types of psychological adaptation. In particular, alloplastic adaptation is carried out by changes in the external world to the existing needs of the individual. Autoplastic adaptation is carried out by changes in the structure of the personality under the conditions of the environment. Distinguish between general and situational adaptation; general adaptation (and adaptability) is the result of a successive series of situational adaptations and is related to it according to the principle of "general-particular". Social adaptation can be described as the absence of experiencing conflict with the environment.

Our interest in the adaptation process is associated with the concept of socio-psychological adaptation. It is understood as a process of overcoming problem situations by a person, during which she uses the skills of socialization acquired at the previous stages of her development, which allows her to interact with a group without internal or external conflicts... In the process of socio-psychological adaptation, a person is able to productively carry out his leading activity, to justify role expectations and, at the same time, self-asserting himself, to satisfy his basic needs, according to F.B. Berezin.

The process of activating and using psychological adaptive mechanisms leads to radical changes in mental state personality. The result of the adaptation process is the formation of qualitatively new properties of the psyche, different from those that the individual had before adaptation. In particular, in the process of adaptation, mechanisms of psychological defenses can begin to form: this is manifested in the partial acceptance of the changes by the personality, in the adaptation of the personality to the changed conditions. But at the same time, complete acceptance of the situation does not occur. This interpretation of adaptation is characteristic of psychoanalytic concepts that mark adaptation as a process carried out with the help of psychological defense mechanisms. Protection contributes to the preservation of the internal properties of the individual, on the one hand, on the other hand, it becomes a kind of mitigation mechanism for adaptation. If the defense does not work or social and psychological conditions affect the personality too negatively, then either a conflict between the personality and the environment may arise as a way of resolving the contradiction, or the stress mechanism is triggered. It should be noted that not all adaptation through development and the learning process is conflictual, requiring the inclusion of psychological defense mechanisms.

Another contradiction associated with the adaptation process arises when the situation of a person's success is identified with the adaptation process. Personal adaptation and adaptation are not directly related to life success and success, and the success of a person in any area should not be considered a sign of adaptability, just as it is wrong to consider every failure a sign of lack of adaptation. A person may not have a good prestigious job, from the point of view of many, not be an excellent student in the class, but at the same time he is perfectly adapted to any social environment and feels comfortable in all plans. On the contrary, a person has a prestigious job, excellent grades at school, but he does not communicate with peers, is not able to come into contact with teachers or other children, he has an overestimated self-esteem that prevents equal communication, he believes that the environment is not worthy of him, as well as and his entourage. In this case, it makes sense to talk about adaptation in the first situation and the lack of adaptation in the second. In addition, it must be borne in mind that not all human needs contribute to its correct functioning and socio-psychological adaptation.

From the point of view of a number of researchers, instincts are a component that is significant for the adaptation process. The instinctive behavior of an individual can be characterized as behavior based on the natural needs of the body. They allow the individual to adapt to the environment for survival and preservation of their own inner "I". There are needs, on the contrary, leading to maladjustment. The adaptability or maladjustment of the need depends on personal values ​​and the object and purpose.

The maladaptivity of a person, according to A.A. Nalchajyan, is expressed in her inability to adapt to her own needs and aspirations. A maladapted person cannot respond to the demands of society, and is also incapable of fulfilling his social role. A person's experience of long-term internal and external conflicts is attributed to the main signs of emerging maladjustment, the trigger for maladjustment is not the presence of conflicts, but the fact that the situation becomes problematic for the individual.

Refer to the level of maladjustment, starting from which the person begins his adaptive activity. This is necessary in order to better understand the features and specifics of the adaptive process. Adaptive activity, according to A. A. Nalchadzhyan, is of two types: situational with the elimination or transformation of the situation, aimed at solving problems in an active way, which allows us to call it “active-activity”; situational with the preservation of the situation, aimed at adapting the individual to the situation. Due to the nature of this situation, it can be called passive, since the result is not an active transformation of the environment, but adaptation to it. Adaptive behavior of different types is distinguished either by successful decision-making, manifestation of initiative and a clear idea of ​​one's future, which will be manifested in active-activity adaptation; or the absence of any solutions, if the person adapts to the world around him.

An individual's acquisition of knowledge, abilities and skills, competence and mastery are signs of effective adaptation; the establishment of personal, emotionally rich connections with the desired person is a sign of effective adaptation in the field of personal relationships; maximum comfort of the student in the educational space, regardless of the level of his academic performance, is a sign of effective adaptation of the individual in the field of education.

So, personality adaptation mechanisms affect different levels personality structures: at the physiological level - instincts and the level of physiological capabilities of the individual, at the psychological level - this is building a system of psychological defense to maximize the preservation of one's own "I", at the socio-psychological level - this is the development of a set of properties and qualities that contribute to successful socialization and psychological adaptation ...

There are three adaptation mechanisms:

1.passive way of adaptation - by the type of tolerance, endurance;

2. the adaptive pathway acts at the cellular and tissue level;

3.resistant pathway - maintains the relative constancy of the internal environment

Specific adaptive mechanisms inherent in humans enable him to tolerate a certain range of deviations of factors from optimal values ​​without disrupting the normal functions of the body. Zones of quantitative expression of physical activity, deviating from the optimum, but not disrupting vital activity, are defined as normal zones. There are two of them: a deviation towards the lack of dosage of physical activity and towards the excess. Further shift can reduce the effectiveness of adaptive mechanisms and even disrupt the vital functions of the organism. With an extreme lack of load or its excess, pessimum zones are distinguished. Adaptation to any factor is associated with energy costs. In the optimum zone, active mechanisms are not needed, and energy is spent on fundamental life processes, the body is in equilibrium with the environment. With an increase in the load and its going beyond the optimum, adequate mechanisms are activated.

Mechanisms providing the adaptive nature of the general level of stabilization of individual functional systems (i.e., the body's oxygen consumption increases, the intensity of metabolic processes increases. This happens at the organ level: the blood flow rate increases, blood pressure increases, the respiratory volume of the lungs increases, breathing becomes more frequent, breathing becomes more deep) and the body as a whole. General adaptive reactions of the body are nonspecific, that is, the body reacts similarly in response to the actions of stimuli of different quality and strength (exercise).

Changes at the cellular level, hormonal changes

Adaptive reactions of the body and its resistance in connection with muscle activity.

The body maintains the relative dynamic constancy of the internal environment necessary for life, although it responds to the action of numerous changing external and internal factors. It is the reaction that is the main way of adaptation, adaptation of living things. Quality and quantity are inherent in each of the operating factors. The quality of the stimulus distinguishes this stimulus from many others, determines the specifics of its action. The amount of a stimulus, a measure of its biological activity, is common, which is characteristic of any stimulus and determines the nonspecific side of its action on the body.

Muscle loading is no exception. Under muscular load, as well as under the action of any stimulus, a number of specific changes occur in the body and a nonspecific reaction develops, associated with a quantitative measure of the load. Of course, the concepts of "quantity", "measure", "force", "dose" in relation to the body are very relative. The degree of biological activity of an active factor is determined not only by the absolute value of this factor, but also by the body's sensitivity to it.

In relation to muscle load, this is of particular importance, since with the help of training it is possible to control the sensitivity and resistance of the body to it. A well-trained athlete can tolerate a muscle load that would be unbearable for an untrained athlete. Despite this, everyone will react differently to the load depending on the change in its value, i.e. the quantitative and qualitative principle will remain: the dependence of the response of the organism on the magnitude of the load.

The non-specific character of the adaptive reaction of the whole organism was first shown by G. Selye; any in quality, but strong stimuli caused the development of the same symptom complex in the body. The specific, special effect of the stimulus persisted, but under the action of any strong stimulus, after 6 hours, there was a decrease in the thymus gland, an increase in the adrenal glands, the presence of ulcers and hemorrhages in the mucous membrane of the alimentary canal. In the blood, leukocytosis, lymphopenia, aneosinophilia were observed. Selye called the general nonspecific adaptive response to a strong stimulus - stress (stress response), and its first stage - an anxiety response. The alarm reaction contains elements of damage, oppression with one-sided sharp stimulation of the ACTH axis - glucocorticoid hormones. In response to a strong impact, it is necessary to quickly mobilize the body's energy resources. This happens under stress, but in an extremely uneconomical and destructive way for the body. After the anxiety reaction, the second stage of stress sets in - the stage of resistance. At this stage, the body's nonspecific resistance increases. If the stressor was excessively strong or its effect is long-term, then the stage of stress depletion develops. The exhaustion stage can lead to death.

For many years, stress was considered the only adaptive response and, along with its negative features, researchers were increasingly interested in the positive - an increase in resistance. Increasing the body's resistance, and even nonspecific - not to one damaging factor, load, but to different ones - this is necessary in sports. However, an increase in stress resistance, according to Selye, comes at the cost of damage and high energy expenditures.

Is there another, milder way of increasing the nonspecific resistance of the organism?

N.V. Lazarev believes that there is such a path. With the help of a number of substances called adaptogens, it caused a state of nonspecifically increased resistance (SNPS), in which the body's resistance increased without elements of damage. This other way is qualitative: certain substances (adanthogens) cause SNPS. It has been established that adaptogens, depending on the dose, can cause SNPS and other complexes of changes, and large doses of adaptogens can even cause stress. It could be assumed that if in evolution a general nonspecific adaptive reaction to a strong stimulus developed, then there must be reactions to weaker, physiological stimuli. Our studies have shown that, in addition to stress, there are two more general nonspecific adaptive reactions of the body: to weak stimuli - a reaction called a training reaction, to medium stimuli (intermediate between strong and weak) - a reaction called an activation reaction.

Thus, a quantitative and qualitative regularity of the development of general nonspecific adaptive reactions was found: depending on the strength, dose, biological activity of acting factors, external and internal environment, qualitatively different adaptive reactions develop in the body.

Changes in the body during the activation reaction have a character than during stress. Already in stage I, - the stage of primary activation, instead of a decrease in resistance, it increases, instead of a decrease in the thymus gland - its significant increase with an increase in the functional activity of lymphoid elements in the endocrine system - a harmonious and well-coordinated moderate increase in the secretion of thyroid hormones, sex hormones and cortical substance adrenal glands mainly due to mineralocorticoids, but without reducing the level of glucocorticoids. This is due to the predominance in the brain (especially in the hypothalamus, where adaptive reactions are formed) of physiological excitation with good functional activity of neuronal and glial elements. In the stage of persistent activation, which develops with a systematic repetition of activation influences, the increase in resistance becomes persistent. The functional activity of the central nervous system and endocrine glands is quite high, but not excessive. This state of neuroendocrine regulation should create favorable conditions for muscle activity. This is also evidenced by the state of the peripheral receptor endings (neuromuscular endings) that provide muscle contractions. If, under stress in the neuromuscular endings, the number of detected nerve fibers decreases, and in the preserved nerve fibers and endings there is a pronounced swelling and uneven impregnation with silver, then with the development of the activation reaction, the nerve fibers and endings are well detected, and in them the silver impregnation is evenly enhanced. This is also indicated by high physical activity and the need for movement, which characterizes the activation reaction and especially the zone of increased activation.

The training reaction got its name because in order to maintain it for a long time in the body, initially weak effects have to be systematically repeated daily, gradually increasing the load, i.e. the principle of any training is used in general. This reaction has signs of similarity with the reaction of activation and stress, but it is characterized by its own complex of changes. In the first stage of the training reaction - the orientation stage - the thymus is not depressed, as in stress, but is less enlarged than in the activation reaction (the difference is statistically significant). An increase in resistance at this stage occurs due to a decrease in sensitivity: protective inhibition prevails in the brain. The function of the genitals and the thyroid gland is not suppressed, but their activity is not as high as during the activation reaction. The secretion of glucocorticoids is increased, but not as sharply as during stress; the secretion of mineralocorticoids is also increased, although not as significantly as during the activation reaction.

The physiological meaning of the adaptation of the organism to external and internal influences is precisely in maintaining homeostasis and, accordingly, the vitality of the organism in almost any conditions to which it is able to adequately respond.

Types of adaptation: distinguish urgent and long-term adaptation.

Urgent adaptation is the body's response to a single exposure to the training load, which is expressed in "emergency" adaptation to the changed state of its internal environment. This answer boils down mainly to changes in energy metabolism and to the activation of the higher nerve centers responsible for the regulation of energy metabolism. As for long-term adaptation, it is formed gradually on the basis of repeated implementation of urgent adaptation by summing up the traces of repeated loads. In the course of adaptation processes, a specific component and a general adaptation response can be distinguished. The processes of specific adaptation affect intracellular energy and plastic metabolism and the associated functions of vegetative services, which specifically respond to this type of influence in accordance with its strength.

The general adaptive reaction develops in response to a variety of stimuli (regardless of their nature) if the strength of these stimuli exceeds a certain threshold level. A general adaptive response is realized due to the excitation of the sympathoadrealin and pituitary-adrenocortical systems. As a result of their activation, the content of catecholamines and glucocorticoids in the blood and tissues increases, which contributes to the mobilization of the body's energy and plastic reserves. This nonspecific response to irritation has been called "stress syndrome", and the stimuli that cause this response have been called "stress factors". The general adaptation syndrome in itself is not the basis for adaptation to training loads, it is only called upon at the system level to ensure the flow of specific adaptive reactions, which form the body's adaptation to specific types of load. Despite the different nature of the processes of specific adaptation, it is possible to identify the general patterns of their course. The basis of specific adaptation is the recovery of energy resources wasted during muscular work, destroyed cell structures, displaced water-electrolyte balance, etc.

V.N. Platonov (1997) distinguishes three stages of urgent adaptation reactions:

The first stage is associated with the activation of the activity of various components of the functional system that ensures the implementation of this work. This is reflected in a sharp increase in heart rate, ventilation level, oxygen consumption, accumulation of lactate in the blood, etc.

The second stage occurs when the activity of the functional system proceeds with stable characteristics of the main parameters of its provision, in the so-called steady state.

The third stage is characterized by a violation of the established balance between the request and its satisfaction due to the fatigue of the nerve centers that provide the regulation of movements and the depletion of the body's carbohydrate resources.

According to V.N. Platonov (1997), the formation of “long-term adaptive reactions” (the author's edition is preserved) also proceeds in stages: In the second stage, against the background of systematically increasing and systematically repeated loads, there is an intensive course of structural and functional transformations in the organs and tissues of the corresponding functional system. At the end of this stage, the necessary hypertrophy of organs is observed, the coordination of the activity of various links and mechanisms that ensure the effective operation of the functional system in new conditions. The third stage is distinguished by stable long-term adaptation, expressed in the presence of the necessary reserve to ensure a new level of functioning of the system, stability of functional structures, close interconnection regulatory and executive mechanisms. The fourth stage occurs with irrationally constructed, usually excessively strenuous training, malnutrition and recovery and is characterized by wear and tear of individual components of the functional system. 35-37. Stages of adaptation to muscle activity. The concept of biological "cost" of adaptation.

Adaptation- This is the adaptation of the structure, functions of organs and the body as a whole, as well as the population of living beings to changes in the environment.

Distinguish between genotypic and phenotypic adaptation. The first is based on the mechanisms of mutations, variability, natural selection. They were the reason for the formation of modern species of animals and plants. Phenotypic adaptation is a process that takes place during an individual's life. As a result, the body acquires resistance to any environmental factor. This allows him to exist in conditions significantly different from normal. In physiology and medicine, this is also the process of maintaining the normal functional state of homeostatic systems, which ensure the development, maintenance of normal working capacity and human activity in extreme conditions.

Complex and cross adaptations are also distinguished. Complex adaptations arise in natural conditions, for example, to the conditions of certain climatic zones, when the human body is exposed to a complex of pathogenic factors (in the North, low temperature, low atmospheric pressure, change in duration daylight hours etc.).

Cross or cross-adaptations are adaptations in which the development of resistance to one factor increases resistance to a concomitant one.

There are two types of adaptive responses. The first type is called passive. These reactions are manifested at the cellular and tissue level and consists in the formation of a certain degree of resistance or tolerance to changes in the intensity of the action of any pathogenic factor of the external environment, for example, low atmospheric pressure. This allows you to maintain normal physiological activity of the body with moderate fluctuations in the intensity of this factor. The second type of adaptation is active. This type consists in the activation of specific adaptive mechanisms. In the latter case, the adaptation is resistive. Those. due to active resistance to impact. If the intensity of the influence of a factor on the body deviates from the optimal value in one direction or another, but the parameters of homeostasis at the same time remain quite stable, then such zones of oscillation are called zones of norm. There are two similar zones. One of them is located in the area of ​​lack of factor intensity, the other in the area of ​​excess. Any displacement of the factor intensity beyond the normal zones causes an overload of adaptive mechanisms and a violation of homeostasis. Therefore, outside the normal zones, zones of pessimum are distinguished

In the adaptation process, there are two stages: urgent and long-term. The first, initial, provides imperfect adaptation. It begins from the moment the stimulus acts and is carried out on the basis of the existing functional mechanisms (for example, increased heat production during cooling). The long-term stage of adaptation develops gradually, as a result of prolonged or repeated exposure to an environmental factor. It is based on the repeated activation of urgent adaptation mechanisms and the gradual accumulation of structural changes. An example of long-term adaptation is the change in the mechanisms of heat generation and heat transfer in cold climatic conditions.

The phenotypic basis is a complex of sequential morphophysiological rearrangements aimed at maintaining the constancy of the internal environment. The main link in the mechanisms of adaptation is the relationship of physiological functions with the genetic apparatus of cells. Under the influence of an extreme environmental factor, the load on the functional system increases. This leads to an increase in the synthesis of nucleic acids and proteins in the cells of the organs included in the system. As a result, a structural trace of adaptation is formed in them. The devices of these cells are activated, performing basic functions: energy metabolism, transmembrane transport, signaling. It is this structural footprint that is the basis for long-term phenotypic adaptation.

However, adaptation mechanisms make it possible to compensate for changes in the environmental factor only within certain limits and for a certain time. As a result of the impact on the body of factors that exceed the capabilities of adaptation mechanisms, dysadaptation develops. It leads to dysfunction of body systems. Consequently, there is a transition of an adaptive reaction into a pathological one - illness. An example of maladjustment diseases is cardiovascular diseases in non-indigenous people of the North.

Types of skeletal muscle contraction. Single muscle contractions and their phases. The sum of muscle contractions. Serrated and smooth tetanus. Optimum and pessimum of irritation (N.V. Vvedennsky)

When a single threshold or suprathreshold stimulation is applied to a motor nerve or muscle, a single contraction occurs. When registering it graphically, three consecutive periods can be distinguished on the resulting curve:

1. Latent period. This is the time from the moment of irritation to the start of contraction. Its duration is about 1-2 ms. During the latency period, PD is generated and spreads, calcium is released from the SR, actin interacts with myosin, etc.

2. Period of shortening. Depending on the type of muscle (fast or slow), its duration is from 10 to 100 msec.,

3. A period of relaxation. Its duration is somewhat longer than shortening.

In the single contraction mode, the muscle is able to work for a long time without fatigue, but its strength is insignificant. Therefore, in the body, such contractions are rare, for example, the fast oculomotor muscles, the flexor muscles of the fingers, can contract. More often, single contractions are summed up.

Summation- this is the addition of two consecutive contractions when two threshold or suprathreshold stimuli are applied to it, the interval between which is less than the duration of a single contraction, but longer than the duration of the refractory period.

There are 2 types of summation: full and incomplete summation. Incomplete summation occurs when repeated irritation is applied to a muscle when it has already begun to relax. Full occurs when repeated stimulation acts on the muscle before the onset of the relaxation period, i.e. at the end of the shortening period. The amplitude of contraction with full summation is higher than incomplete. If the interval between two stimuli is further reduced, for example, by applying the second in the middle of the shortening period, then there will be no summation, because the muscle is in a state of refractoriness.

Tetanus- This is a prolonged contraction of a muscle resulting from the summation of several single contractions that develop when a number of successive stimuli are applied to it. There are 2 forms of tetanus: serrated and smooth.

Scalloped tetanus observed if each subsequent irritation acts on the muscle when it has already begun to relax. Those. incomplete summation is observed. Smooth tetanus occurs when each subsequent irritation is applied at the end of the shortening period. Those. there is a complete summation of individual abbreviations. The amplitude of the smooth tetanus is greater than that of the dentate. Normally, human muscles contract in the smooth tetanus mode. Toothed occurs in pathology, for example, tremor of the hands with alcohol intoxication and Parkinson's disease.

The mechanism of the action potential emergence. Movement of sodium and potassium ions upon excitation. Experiments proving the importance of sodium ions in the origin of the action potential. The concept of electromechanical support.

Further studies by Hodgkin and Huxley showed that when the squid axon is excited, a rapid oscillation of the membrane potential occurs, which on the oscilloscope screen had the shape of a spike. They called this fluctuation the action potential (AP). Since the electric current for excitable membranes is an adequate stimulus, PD can be induced by placing a negative electrode on the outer surface of the membrane - the cathode, and the inner positive one - the anode. This will lead to a decrease in the magnitude of the membrane charge - its depolarization. Under the action of a weak subthreshold current, passive depolarization occurs, i.e. a cathelectroton appears. If the current strength is increased to a certain limit, then at the end of the period of its impact on the plateau of the catelectroton, a small spontaneous rise will appear - a local or local response. It is a consequence of the opening of a small part of the sodium channels under the cathode. At the current of the threshold force, the MF decreases to the critical level of depolarization (KUD), at which the generation of the action potential begins. For neurons, it is approximately at a level of -50 mV.

The following phases are distinguished on the action potential curve:

1. Local response (local depolarization) preceding the development of PD.

2. Phase of depolarization. During this phase, the MP rapidly decreases and reaches zero. The depolarization level rises above zero. Therefore, the membrane acquires the opposite charge - inside it becomes positive, and outside it becomes negative. The phenomenon of a change in the membrane charge is called membrane potential reversal. The duration of this phase in nerve and muscle cells is 1-2 ms.

3. The phase of repolarization. It starts when a certain MF level is reached (approximately +20 mV). The membrane potential begins to quickly return to the resting potential. The duration of the phase is 3-5 ms.

4. The phase of trace depolarization or trace negative potential. The period when the return of the MP to the resting potential is temporarily delayed. It lasts 15-30 ms.

5. The phase of trace hyperpolarization or trace positive potential. During this phase, the MP for some time becomes above the initial level of the PP. Its duration is 250-300 ms.

The AP amplitude of skeletal muscles is on average 120-130 mV, neurons 80-90 mV, smooth muscle cells 40-50 mV. When neurons are excited, PD occurs in the initial segment of the axon - the axonal hillock.

The appearance of AP is due to a change in the ionic permeability of the membrane upon excitation. During the period of a local response, slow sodium channels open, while the fast ones remain closed, and temporary spontaneous depolarization occurs. When the MP reaches a critical level, the closed activation gates of sodium channels open and sodium ions rush into the cell like an avalanche, causing increasing depolarization. Both fast and slow sodium channels open during this phase. Those. the sodium permeability of the membrane increases sharply. Moreover, the value of the KUD depends on the sensitivity of the activation gate (the higher it is, the lower the KUD, and vice versa).

When the value of depolarization approaches the equilibrium potential for sodium ions (+20 mV), the strength of the sodium concentration gradient decreases significantly. At the same time, the process of inactivation of fast sodium channels begins and the sodium conductivity of the membrane decreases. Depolarization stops. The yield of potassium ions is sharply increased, i.e. potassium outgoing current. In some cells, this is due to the activation of special channels of potassium outgoing current. This current, directed from the cell, serves to quickly displace the MF to the level of the resting potential. Those. the repolarization phase begins. An increase in MF leads to the closure of the activation gates of sodium channels, which further reduces the sodium permeability of the membrane and accelerates repolarization. The appearance of the phase of trace depolarization is explained by the fact that a small part of the slow sodium channels remains open.

The trace hyperpolarization is associated with the increased potassium conductivity of the membrane after the generation of PD and the fact that the sodium-potassium pump works more actively, which removes the sodium ions that entered the cell during PD.

By changing the conductivity of fast sodium and potassium channels, it is possible to influence the generation of AP, and, consequently, the excitation of cells. With a complete blockade of sodium channels, for example, by the poison of tetrodont fish - tetrodotoxin, the cell becomes non-excitable. This is used in the clinic. Local anesthetics such as novocaine, dicaine, lidocaine inhibit the transition of the sodium channels of nerve fibers to the open state. Therefore, the conduction of nerve impulses along the sensory nerves stops, anesthesia (anesthesia) of the organ occurs. With the blockade of potassium channels, it is difficult for potassium ions to escape from the cytoplasm to the outer surface of the membrane, i.e. restoration of MP. Therefore, the repolarization phase is lengthened. This effect of potassium channel blockers is also used in clinical practice. For example, one of them, quinidine, lengthening the phase of cardiomyocyte repolarization, slows down the heart contractions and normalizes the heart rhythm.

It should also be noted that the higher the rate of AP propagation along the cell or tissue membrane, the higher its conductivity.

The transmission of a signal from an excited membrane to myofibrils is called electromechanical coupling. When the AP generation stops and the membrane potential returns to baseline, the Ca-pump (Ca-ATPase enzyme) starts to work. Calcium ions are again pumped into the cisterns of the sarcoplasmic reticulum and their concentration drops below 10-8 mol. Troponin molecules return to their original form and tropomyosin again begins to block the active centers of actin. The myosin heads are detached from them and the muscle, due to elasticity, returns to its original relaxed state.