Stress. Hans Selye Stress Theory. Physiological response of the organism to stress.

Hans Selye Stress Theory. Physiological response of the organism to stress

Hans Selye Stress Theory

The study and description of stress in its physiological aspect is due to the Canadian endocrinologist Hans Selye (1907-1982), who views stress as the “universal response of the human organism to various stimulants,” called by him “stressors.” We can say that Selye defines stress as a “shock to the body”. He discovers that each organism reacts in the same way, and the body’s effort has a specific purpose of adaptation and survival, and hence calls this aggregation of reactions a “common adaptation syndrome.” According to Selye’s classification, the positive is referred to as stress and the negative as distress. As we notice, Selye does not pay attention to mental processes. For his part, Lazarus emphasizes the specificity of psychic reactions and talks about mental stress, defining it as a “two-way, dynamic, continuously changing the interaction between personality and the environment.”

Speaking of stress, we need to mention the system-forming factor, and that is precisely the subjective assessment of the extreme situation and the ability of the individual to deal with it.

Physiological response of the organism

After looking at some definitions of stress, we focus our attention beyond Hans Selye Stress Theory on the physiology of stress or what happens to our body when it is stressed, which is:

If too much muscle or nervous-psychical activity is present, the level of catecholamines in the blood increases (tyrosine derivatives, catabolic or stress hormones such as adrenaline, noradrenaline and dopamine – these are a group of hormones secreted by the adrenal gland). They have a number of effects, such as increased blood levels, blood sugar levels, etc. Immediately a response to the nervous system arises, which activates the sympathetic nervous system (SNS) (a sympathetic part of the nervous system that speeds up heart activity, expands the bronchi, suppresses the movement and secretion of the digestive system, blocks the excretory system, increases the intraocular pressure, enlarges the pupils of the eyes and so on). What is more, the function of catecholamines is to activate the hypothalamus (a higher centre of the autonomic nervous system which is formerly called the vegetative nervous system and which also has excretory functions, that is, it also functions as an internal secretory gland, located at the base of the cerebellum) and its hormonal secretion, by which it is able to regulate body temperature, appetite, excretory system, blood sugar levels. Adrenal hormones serve as mediators, triggering the already created and accumulated hypothalamic hormones by which they act on glands such as the pituitary gland. Probably much of the nervous system reaction is provoked by the hypothalamus, which has a pronounced neuroregulatory function. The hypothalamus also has a proven relationship to sleep and alertness. Modern science attributes to the hypothalamus’s stimulus and some of the emotions. For example, fear and fury can be induced artificially by stimulating the hypothalamus. These two feelings are a common companion in stressful situations. By stimulating the hypothalamus, it is also proven its connection with motivation, with the emergence of a certain desire to do something, although in this case, the connection is more complicated and dependent on other factors.

However, the relationship continues. The hypothalamus produces groups of hormones classified as releasing (releasing factors/hormones) or liberins and statins. Through the anterior pituitary (also called the adenohypophysis or pars anterior) liberins activate the secretion of pituitary hormones and the statins block that same secretion. For example, somatoliberin and somatostatin release or block the secretion of somatotropin (also known as human growth hormone); corticotropin-releasing hormone (CRH or corticoliberin), thyrotropin-releasing hormone (TRH or thyroliberin) and gonadotropin-releasing hormone (GnRH or gonadoliberin) respectively activate the secretion of corticotropin, thyrotropin and gonadotropin.

Through the adenohypophysis, the hypothalamus may actually affect the adrenal glands – for example, it can affect the factor that unleashes stress or the gonads, even the thyroid gland. That is, the entire endocrine system and hence the whole organism.

All these processes taking place in our body, as we said above, have a specific purpose – adaptation and survival. And the main answer that our “oldest” brain (from the limbic system) has is to come down to three basic actions, two of which we can call conditionally passive and one active, namely, freezing, escaping and battle. All these processes are the preparation of the body to react to the stressful situation 

Тhe stages of Hans Selye:

Hans Selye Stress Theory describes the stages that a person pass through in a stressful situation. It has formulated a total of three main stressful stages:

Stage of anxiety, alarm reaction. This is the stage of unlocking stress in the body. The processes mentioned above are taking place at this stage. It lasts for several hours to two days, depending on the irritation. Here, the body “allows” the stress in. The reaction leading to termination is detained. The body’s resistance to stress at this stage is low.

Stages of increased resistance – elevated blood pressure, body temperature, and the like, cause blockage of certain hormones, and elevated blood sugar levels, for example, increase insulin secretion, which in turn inhibits many of the stress hormones. Gradually and controlled, the body returns to its normal levels of functioning. This is the normal end of stress.

The phase of exhaustion – this stage occurs if the stress factor is constant, for example psychologically, or if the body is unable to cope with the problem. Here is already reached the stage of “saturation” of the body due to an ineffective and very long stress reaction. Permanent nervous stimulation acts in a neurochemical way and weakens at each subsequent impulse, over time, it costs a lot of the body’s effort, but ceases to perform its functions effectively; permanently elevated levels of hormones lead to saturation of receptors and increased cell resistance. Without
eliminating the stress factor, the body’s reactions diminish, the immune system weakens. Some stress symptoms also disappear, but overall the condition is sick, it may even be life-threatening. The body’s ability to react is minimized.

There is surficial adaptation energy as well as deep adaptation energy. The first one is immediately accessible and the second is stored as a reserve. The state of exhaustion after a temporary requirement for the body is a reversible state, but the full consumption of all the supplies of deep adaptation energy is irreversible. After the depletion of these reserves, death occurs.

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