Functional states of the body. Stress, its physiological significance

15.10.2023 -

Physiology of stress

When exposed to an irritant (stressor), the entire system “connects” and tries to answer the question “what happened?” These processes occur offline. physiological processes are combined with psychological ones, which at this stage are manifested by direction of gaze, increased attention, listening, concentration on stressors, muscle tension occurs, as well as activation of the end organ. this is a manifestation of an orienting reflex, which can transform into a stress reaction if the signal is perceived as threatening. If the perception of threat does not occur, then the stress response does not occur.

Any irritant that causes stress reaction must first be perceived (though not necessarily consciously) by receptors. Having perceived this irritation, the receptors send impulses along the sensory pathways of the peripheral nervous system to the brain. In the central nervous system, from the main pathways ascending to the neocortex, nerve branches depart, heading to the reticular formation and further to the formations of the diencephalon. Therefore, perceived events receive proper assessment in the brain structures associated with providing the motivational-need sphere of a person (the hypothalamus and limbic system).

Ultimately, all flows of nerve impulses along ascending pathways enter the cerebral cortex, where their meaningful, semantic interpretation is carried out. The results of this interpretation flow through feedback channels into the limbic system. If a stimulus is interpreted as a threat or challenge that provokes a pronounced emotional assessment, a stress response occurs. For many people, the activation of emotions (both negative and positive) is a trigger for stress.

So, in the most general form, the conditions for the occurrence of a stress response are as follows: any stimulus receives a double interpretation - an objective one, reflecting the physical characteristics of the impact, and a subjective one, reflecting the subject’s attitude to this impact. If the subjective assessment indicates a threat, i.e. has a negative affective connotation (fear, anger), it triggers a sequence of corresponding physiological reactions.

The main way the stress response spreads in the body is the autonomic nervous system and, first of all, its sympathetic department, the effects of stimulation of which were described above.

So, as already emphasized, in the modern world, stress reactions to psychosocial stimuli are not so much a consequence of the stimuli themselves, but rather the result of their cognitive interpretation, as well as emotional arousal.

The set of adaptive reactions of the body to adverse effects (stressors) of significant strength and duration is defined as general adaptation syndrome (OAS). Selye developed the concept of this syndrome in 1956, defining OSA as the body's effort to adapt to changed environmental conditions by incorporating special protective mechanisms developed during the process of evolution. OSA is divided into three stages:

· The first is called the anxiety stage. This stage is associated with the mobilization of the body’s defense mechanisms and an increase in the level of adrenaline in the blood.

· The next stage is called the stage of resistance or resistance. This stage is distinguished by the highest level of body resistance to the action of harmful factors, which reflects the ability to maintain a state of homeostasis.

· If the impact of the stressor continues, then eventually the “energy of adaptation”, i.e. adaptive mechanisms involved in maintaining the stage of resistance will exhaust themselves. Then the body enters the final stage - the stage of exhaustion, when the survival of the organism may be at risk.

The essence of OSA is clearly stated by Selye himself: “No organism,” he emphasizes, “can be constantly in a state of anxiety. If the agent is so strong that its significant impact becomes incompatible with life, the animal dies even at the alarm stage, during the first hours or days. If it survives, the initial reaction is necessarily followed by a stage of resistance. This stage is responsible for the balanced expenditure of adaptation reserves. At the same time, the existence of the organism practically no different from the norm is maintained under conditions of increased demands on its adaptive capabilities. But since adaptive energy is not unlimited, then if the stressor continues to act, the third stage begins - exhaustion.”

The human body copes with stress in the following ways: ways:

1. Stressors are analyzed in the higher parts of the cerebral cortex, after which certain signals are sent to the muscles responsible for movement, preparing the body to respond to the stressor.

2. The stressor also affects the autonomic nervous system. The pulse quickens, the pressure rises, the level of red blood cells and blood sugar increases, breathing becomes frequent and intermittent. This increases the amount of oxygen supplied to the tissues. The person is ready to fight or flee.

3. From the analyzing parts of the cortex, signals enter the hypothalamus and adrenal glands. The adrenal glands regulate the release of adrenaline into the blood, which is a common fast-acting stimulant.

The hypothalamus transmits a signal to the pituitary gland, which sends a signal to the adrenal glands, resulting in an increase in the synthesis of hormones and their release into the blood. Hormones mainly provide slow-acting protection to the body. They change the water-salt balance of the blood, increasing blood pressure, stimulating rapid digestion of food and releasing energy; hormones increase the number of white blood cells in the blood, stimulating the immune system and allergic reactions.

4. The most long-lasting somatic reactions to stress are the result of activation of “endocrine axes,” that is, systemic associations of organs, the result of which will be changes in the production of hormones. The human stress response involves the somatotropic, adrenocortical and thyroid systems. They are associated with activation of the hypothalamic-pituitary system of the cortex and the adrenal medulla and thyroid gland. It has been shown that these axes can be activated through numerous and varied psychological interventions, including various psychosocial stimuli. The reaction along the endocrine axes not only lasts a long time, but as a rule occurs with some delay. The latter is due, firstly, to the fact that the only transport mechanism for these axes is the circulatory system, and secondly, to the fact that a stronger stimulus is required to activate them.

This first stage adaptive syndrome, which Selye called the anxiety stage. This is actually the first level of response to a stressor - the level of autonomous nervous axis which is bioelectric in nature.

If the stressor is regarded as threatening, which can happen with prolonged exposure to the stressor, increasing the intensity of the impact, etc., the following is included ( second phase (level) of the stress process - the stage of tension. At this stage, the body prepares to overcome this threat. Through the sympathetic and parasympathetic pathways, the nerve impulse, after cortical and limbic “interpretation” of the stressor, descends to the hypothalamus, from where it reaches the corresponding end organ through the pathways (ergotropic and trophotropic reactions). the most important effect of activation of the autonomic nervous system is its manifestation immediately at the end organ. the body mobilizes to overcome the “threat” - pressure rises, heart rate increases, breathing rhythm changes, muscles tense, internal organs switch to a “special mode of operation.” the barrier of the adapted mental response approaches an individual critical value; All reserve capabilities are connected under full control of the individual.

However, the action of the autonomic nervous axis does not last long and its effectiveness quickly decreases.

Therefore, to overcome the ongoing “threat”, the third level of the stress process is activated - the so-called neuroendocrine axis through which the body implements the “fight-flight” response. A state arises that is characterized by a tendency to actively maintain a certain level of functioning in constantly changing conditions of the external and internal environment, called homeostasis.

Homeostasis is the body's adaptive tendency to maintain balance. this process is ensured by the activity of the neuroendocrine stress response axis. First, the process involves the amygdala, which is the highest center of the fight-flight or stress response; from here the flow of nerve impulses is directed to the hypothalamic region and further to the adrenal medulla, which releases mediators such as adrenaline and norepinephrine into the bloodstream.

Prolonged tension in the functional activity of the mental adaptation barrier leads to its overstrain. under the influence of a continuing “threat”, a state of “mismatch” arises (at the mental level - fear), which is assessed as negative and is accompanied by strong emotional arousal, the biological meaning of which is to transfer the body to an “emergency level” of adaptation. thus, emotional stress reactions (“acute stress” according to ICD-10) and neurotic disorders as a result of mental trauma are formed and manifested - hypersensitivity, insomnia, anxious tension, elements of lethargy or fussiness, etc. these violations are transient and do not upset the adequacy of behavior.

It is important to note that the action of the autonomic nervous system lasts only a few seconds,

Connecting the neuroendocrine axis stretches the reaction tenfold.

But only connection endocrine axis(third level of the stress process) adaptation syndrome extends the stress response for a long time, and often leads to pathological changes. This development of the condition is observed with continued pressure on the barrier of mental adaptation, which leads to depletion of activity. as a result, the adaptive framework of mental activity is narrowed and new forms of adaptive and defensive reactions - neurotic and other manifestations - appear. Such conditions are the basis for the formation of psychosomatic diseases.

The endocrine axis is activated not only during the ongoing action of a real stressor, but also during the action of the so-called “echo stressor” (Tadevosyan A., 2002) - this is the deepest level of the stress process.

There are three main endocrine axes: adreno-cortical, somatotropic and thyroid. these axes support the stress process and require more intense and prolonged stimulation to activate. Human endocrine axes can be activated by numerous and varied psychological, physical and psychosocial influences.

· the adreno-cortical endocrine axis provides specific physiological mechanisms of the stress response by directing impulses from this center to the median eminence of the hypothalamus, the cells of which secrete corticotropin-releasing factor. This factor, released into the hypothalamic-pituitary portal system, acts on the cells of the anterior pituitary gland and causes, in turn, the release of adrenocorticotropic hormone into the bloodstream. Through the blood, adrenocorticotropic hormone enters the adrenal cortex and “forces” it to secrete glucocorticoid hormones: cortisol and corticosterone. the effect of glucocorticoid hormones is manifested in increased glucose synthesis (glucogenesis), an increase in the amount of urine, and the synthesis of ketone bodies; glucocorticoid hormones increase the release of free fatty acids into the circulatory system, increase the risk of myocardial infarction, and cause thymicolymphatic atrophy.

Adrenocorticotropic hormone also promotes the release of mineralocorticoids - aldosterone and deoxycorticosterone into the blood. These hormones regulate electrolyte levels and blood pressure. expected to influence immunological mechanisms.

· in cases where the anterior pituitary gland is stimulated by somatotropin-releasing factor, the somatotropic endocrine axis is triggered. The anterior pituitary gland responds to the influence of somatotropin-releasing factor by releasing growth hormone - somatotropic hormone - into the circulatory system. Growth hormone is thought to increase insulin resistance and accelerate the mobilization of stored fat in the body. the result is an increase in the concentration of free fatty acids and glucose in the blood.

· activation of the thyroid endocrine axis is associated with the septum-hippocampus complex and the median eminence. Thyrotropin-releasing factor from the median eminence goes through the portal system to the anterior pituitary gland, causing the latter to release thyroid-stimulating hormone into the bloodstream, which activates the thyroid gland. In humans, psychosocial stimulation leads to an increase in thyroid activity, which increases the overall metabolic rate, heart rate, cardiac contractility, peripheral vascular resistance (which leads to increased blood pressure), and the sensitivity of some tissues to catecholamines.

Endocrine axes represent the final links in the response to stressors. They are activated under strong intense stimuli or under the influence of prolonged chronic stress. All noted axes of the stress response mutually overlap and have the ability to be activated under chronic stress. the action of each axis is discrete. but if the stressor continues, the “overlapping” of the axes creates a continuity effect.

When unexpectedly exposed to stress, all axes are not always connected simultaneously or alternately. This is possibly due to some individual characteristics that are genetic or acquired.

Hormones that are produced under stress, necessary in physiological quantities for the normal functioning of the body, in large quantities cause many undesirable reactions leading to diseases and even death. Their negative effect is aggravated by the fact that modern man, unlike primitive people, rarely uses muscle energy when stressed. Therefore, biologically active substances circulate in the blood in elevated concentrations for a long time, preventing either the nervous system or internal organs from calming down.

New direction in medicine : psychosomatic medicine. (considers all possible forms of stress as the main or concomitant pathogenetic factor of many somatic (physical) diseases.

Some Western experts estimate that 70% of diseases are associated with emotional stress. In Europe, more than a million people die every year due to stress-related disorders of the cardiovascular system. The main causes of these disorders are emotional stress, interpersonal conflicts in the family and tense industrial relations, etc.

Meaning of stress:

From the point of view of biological feasibility (using the “fight or flight strategy”) stress increases efficiency functioning of organ systems - for example, when a person runs away from an aggressive dog or participates in a sports competition.

A decrease in performance occurs only when natural behavior programs conflict with social norms or conditions of intellectual activity (which manifests itself, for example, in the stress of air traffic controllers or stockbrokers).

It is necessary to distinguish between concepts "psychological stress" And "emotional stress":

emotional stress is inherent not only in humans, but also in animals, while psychological stress occurs only in humans with their developed psyche;
emotional stress is accompanied by pronounced emotional reactions, and the cognitive component predominates in the development of psychological stress (analysis of the situation, assessment of available resources, making a forecast of further events, etc.);
the term “emotional stress” is more often used by physiologists, and the term “psychological stress” by psychologists.

At the same time, both of these types of stress have a common development pattern and include similar neurohumoral the mechanisms of adaptive reactions in their development, as a rule, go through three “classical” stages - anxiety, adaptation and exhaustion.

Everyone reacts differently to an external stressor. This shows his individuality. Consequently, personality characteristics are most closely related to the form of response to a stressor and the likelihood of developing negative consequences.

Stress management, overcoming it:

« You shouldn't be afraid of stress. Only the dead do not have it. Stress must be managed. Managed stress brings the flavor and taste of life».
Hans Selye

Helps overcome stress:

Physical activity(long-term exercise, cardiovascular exercise, which strengthens the heart and lungs, helps reduce depression and anxiety)
Positive, optimistic attitude, good mood.
Relaxation(ability to relax, calm down, hobby).
Moral support(the presence of friends, relatives, loved ones - those who are ready to help and support you in difficult times).
Spirituality(religiosity).
No bad habits(smoking, overeating) - that is, controlling normal weight, quitting smoking.

Stress management - y a universal algorithm for stress management, aimed not at counteracting the energy of stress, but allowing one to use this energy in the interests of personal growth and self-improvement.

1. Timely recognition of stress.

The goal is to start searching for the cause of stress in time in order to change it;
2. Choosing optimal behavior.

The goal is to master the stressful situation;
3. Using anti-stress self-defense techniques.

The goal is to transform stress from a destructive force into a creative force;
4. Restoring spent resources, counteracting chronic fatigue.

The goal is to prevent stress diseases.

The physiological type of stress is a direct response of a living organism to sudden changes in the environment. Stressful conditions are characterized by sharp physiological changes that change the neurohumoral and autonomic processes of physiological regulation in the human body. Thus, stressful conditions affect all vital processes of the body, changing metabolism and sensitization.

Physiology of stress

Let's try to figure out what the physiology of stress is.

Stressful conditions accompany a person every day. Without noticing it, he constantly reacts to many external stimuli, even during sleep. The body independently responds to loud screams, a sudden windy current on the street, a crying child, a fight between strangers, a crush on a trolleybus, etc.

Under the influence of a stimulus, the entire system “connects” and tries to “find out” what happened. These processes occur autonomously, combined with psychological ones. Muscle tension, increased attention, hypermnesia or a complete lack of remembering any events, listening, and switching attention to the factor that caused stress occur. The person is anxious, his sleep is disturbed, he sees threats from everywhere. He associates any events occurring at this moment solely with the factor that provoked the stress.

Stress is multifaceted. Stress is usually characterized by psychological pressure, physical activity, overwork, emergency situations, negative information that provokes a response from the body, mobilizing energy. In psychology, the term “distress” is used, which implies trouble, exhaustion, severe malaise, or the sudden loss of something or someone close. This condition is indicated by severe stress of a very unpleasant nature.

In fact, most events and situations that occur in our daily lives should not be perceived as stressful by us. It is only our own reaction that makes them so. Psychologists convince us that there is no such thing as good or bad information. Any information is neutral, we “convert” it into good or bad ourselves. The exception is physical injuries. Stressful situations sometimes arise between close people due to different attitudes towards a particular problem. Everyone sees it in their own way, sometimes even very close partners have diametrically opposed opinions.

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Classification of stress

Stress comes in different types:

emotionally negative;
emotionally positive;
short-term;
long lasting;
spicy;
chronic;
physiological;
psychological.

Physiological and psychological stress are divided into emotional and informational.

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Symptoms of stress

To understand what stress is, you need to listen to its symptoms:

irritation, often groundless;
sleep disorders;
decreased concentration;
memory impairment;
“loss” of thoughts that come to mind even in moments of peace;
inability to relax;
loss of interest in loved ones;
apathy;
unreasonable self-pity;
feeling of hopelessness;
loss of appetite;
excessive absorption of food;
nervous tics;
new bad habits;
increased distrust of others;
frequent constipation;
causeless fussiness.

If a person observes similar symptoms in himself, it means that his body has reacted to some external stimulus, generating stress within himself.

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Stress factors

Residents of large cities are the most susceptible to stressful conditions: their psyche is the most vulnerable and mobile due to the heavy load on the nervous system due to the large flow of information and external noise that has become a constant daily background. A special place is occupied by office workers, who spend most of their working time in a limited space in a motionless position.

Factors of any type of stress can be divided into external and internal. External factors include excessive workload, divorce, loss of a loved one, or the incurable illness of a loved one. Internal factors include a lack of vitamins and microelements in the body due to poor nutrition, metabolic disorders, some chronic diseases, and insomnia.

Psychiatrists have their own scale of factors that cause stress. In the first place, of course, is the death of a loved one. And such, as it seems at first glance, everyday events in the life of any person, such as divorce, pregnancy, difficult childbirth, physical injuries, debts, dismissal from work, moving, retirement, even holidays and vacations, are completely objective reasons for the occurrence of all those same stressful situations that destroy the body. They occupy positions equidistantly on the same scale.

But if you look deeper into the problems of people experiencing stress, it will be extremely surprising to discover that people do not worry about global events in their lives as much as they do because of little things, such as a scandal on the bus on the way to work, forced standing in a long line at the store, losing your wallet. All this indicates that our health is negatively affected by everyday problems, which we, by and large, cannot avoid.

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Physiological stress

Many people do not understand what the physiological type of stress is. This type of stress is a consequence of excessive physical activity, sudden or constant exposure to external factors, such as industrial noise, changes in ambient temperature, hunger, thirst, and pain symptoms of any disease.

A striking example today is the body’s unpredictable reaction to a deliberate reduction or complete refusal of food - a diet. It seems to us that health should be restored while following a diet, that fat deposits will be used at the time of giving up usual foods, but in fact the body is experiencing stress that occurs at the cellular level. The cell, sensing that something is going in a way unusual for the life of the body, begins to send impulses to the brain indicating the storage of nutrients, which leads to new deposits of adipose tissue. Moreover, during periods of long-term diets, a person becomes more irritable, sleeps poorly, suffers from constipation, and one can say that he is nervous for no reason.

There is also a diametrically opposite scientific opinion about the attitude towards physiological stress. Scientists believe that it is beneficial for the body, because in some way it strengthens it, making the nervous system more mobile. This is especially true for children whom their parents decided to harden using unconventional methods, such as dousing them with ice water from an early age, or swimming in an ice hole. If we reject this theory, then the child will grow up “greenhouse”, susceptible to various diseases, and physically weak.

Physiology of stress

The main way the stress response spreads in the body is the autonomic nervous system and, first of all, its sympathetic department, the effects of stimulation of which were described above.

· The first is called the anxiety stage. This stage is associated with the mobilization of the body’s defense mechanisms and an increase in the level of adrenaline in the blood.

The human body copes with stress in the following ways: ways:

1. Stressors are analyzed in the higher parts of the cerebral cortex, after which certain signals are sent to the muscles responsible for movement, preparing the body to respond to the stressor.

4. The most long-lasting somatic reactions to stress are the result of activation "endocrine axes" that is, systemic associations of organs, the result of which will be changes in the production of hormones. The human stress response involves the somatotropic, adrenocortical and thyroid systems. They are associated with activation of the hypothalamic-pituitary system of the cortex and the adrenal medulla and thyroid gland. It has been shown that these axes can be activated through numerous and varied psychological interventions, including various psychosocial stimuli. The reaction along the endocrine axes not only lasts a long time, but as a rule occurs with some delay. The latter is due, firstly, to the fact that the only transport mechanism for these axes is the circulatory system, and secondly, to the fact that a stronger stimulus is required to activate them.

However, the action of the autonomic nervous axis does not last long and its effectiveness quickly decreases.

Prolonged tension in the functional activity of the mental adaptation barrier leads to its overstrain. under the influence of a continuing “threat”, a state of “mismatch” arises (at the mental level – fear), which is assessed as negative and is accompanied by strong emotional arousal, the biological meaning of which is to transfer the body to an “emergency level” of adaptation. thus, emotional stress reactions (“acute stress” according to ICD-10) and neurotic disorders as a result of mental trauma are formed and manifested - hypersensitivity, insomnia, anxious tension, elements of lethargy or fussiness, etc. these violations are transient and do not upset the adequacy of behavior.

! It is important to note that the action of the autonomic nervous system lasts only a few seconds,

Connecting the neuroendocrine axis stretches the reaction tenfold.

But only connection endocrine axis(third level of the stress process) adaptation syndrome extends the stress response for a long time, and often leads to pathological changes. This development of the condition is observed with continued pressure on the barrier of mental adaptation, which leads to depletion of activity. as a result, the adaptive framework of mental activity is narrowed and new forms of adaptive and defensive reactions—neurotic and other manifestations—appear. Such conditions are the basis for the formation of psychosomatic diseases.

When unexpectedly exposed to stress, all axes are not always connected simultaneously or alternately. This is possibly due to some individual characteristics that are genetic or acquired.

In the course of research, experts found that stress occurs in the body as a result of exposure to stress factors or stressors. In this case, stressors can be both external and internal. We will get to know them more closely in the article.

Physiology of stress

As already mentioned, the physiology of the stress process can be explained by:

external stressors (cold, heat, wind);
internal stressors (hunger, pain, emotions, thirst).

Exposure to a stressor on the body leads to the emergence of a stress response and triggers the stress process itself. The very scheme of stress development is as follows: anxiety-adaptation-exhaustion.

The first reaction that accompanies the physiology of stress is a state of anxiety. Here, the autonomic nervous system is directly involved in the process, which a person is not able to control on his own. It immediately reacts to all changes in the environment, and the degree of change in its work depends on the strength of the resulting reaction. It is thanks to the influence of the autonomic nervous system that our body is able to adapt to external factors. So, in the dark the pupils dilate, and in bright light the pupils constrict, the hand withdraws from the hot surface, and so on.

Alarm reaction

Separately, we should consider the anxiety reaction, in which a person receives information about a change in the autonomic system and begins to prepare resources that would allow him to respond appropriately to an external stimulus.

The physiology of stress is structured in such a way that any reaction, be it negative or positive, requires energy. Therefore, the autonomic system triggers a reaction to increase metabolism, which increases the supply of oxygen to the brain and other vital organs. This is where the work of the nervous system ends. In order to convey information to the body about the changes that have occurred and make preliminary preparations, the autonomic system requires a split second.

The physiology of stress also includes effects on the endocrine system, which allows hormones to regulate processes in the body. In the future, it is this system that interacts with the body. The changes that have occurred are maintained due to the release of the hormone adrenaline.

The physiology of stress includes, in addition to the anxiety reaction, a number of other capabilities of the body. The most important among them are the adaptation reaction and the exhaustion reaction. Therefore, attention should also be paid to them in order to better understand the patterns of stress processes.

Functional states of the body. Stress, its physiological significance

Physiology of stress

Classification of stress

Symptoms of stress

Stress factors

Physiological stress

Physiology of stress

Alarm reaction

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