There are three types of theoretical models that attempt to explain stress, Depending on whether they consider stress as a response, as a stimulus or as an interaction between the stimulus and the response.
Here we will know a model based on the answer, General adaptation syndrome of Selye. Selye’s model considers stress as a dependent variable and sets up his theory by considering stress as the body’s response. We will get to know it in detail in this article.
Hans Selye: stress in response
Hans Selye was an Austro-Hungarian physiologist and physician, Born in Vienna in 1907, who developed a theory to explain general adaptation syndrome (GAS). Selye defined stress as a general stereotypical response involving activation of the hypothalamic-pituitary-adrenal (HPA) axis and the autonomic nervous system (ANS).
According to the author, the body is activated by a source of stress. If the activation persists, “Stress Syndrome” or General Adaptation Syndrome will appear.
The appearance of SGA leads to the appearance of various changes at the physiological level. Three of the most important are:
- Hyperplasia of the adrenal cortex (Abnormal increase in height).
- Involvement of the scam (reduction in size and weight).
- Development of a peptic ulcer (open sores that develop in the inner lining of the stomach and upper intestine).
What is general adaptation syndrome?
The constraint operationally defined by Selye based this definition on 2 objectivable phenomena:
It is all this demand that exceeds the resources of the individual and it evokes the stress response pattern or general adaptation syndrome.
2. Stress response
This is the general adaptation syndrome itself. Its onset involves a series of changes that occur as a result of the prolonged presence of a stressor. Outraged, this activation response is widespread (Affects the whole body) and nonspecific (appears in any stressful situation).
Phases of development
On the other hand, Selye differentiates three phases of the general adaptation syndrome:
1. Alarm phase
At the physiological level, at this stage two systems are activated: the neural and the neuroendocrine. This phase appears immediately after the threat. Different hormones are released: adrenaline, corticotropin and corticosteroids, aimed at mobilizing resources.
This phase, in turn, is divided into two sub-phases:
1.1. Shock phase
This is the most immediate reaction, and involves tachycardia, hypotonia, decrease in temperature and blood pressure.
1.2. Shock phase
It is a rebound reaction, which involves the enlargement of the adrenal cortex and the involution of the scam. Opposite signs of the shock phase appear.
In the alarm phase, two things can happen: whether the situation is overcome or not. If overcome, the general adaptation syndrome ends; if it is not exceeded, the resources mobilized are reduced and the second phase appears: the resistance phase.
2. Resistance phase
Here, the activation of the organism is high, although lower than in the previous phase. This activation can last longer because the body in some way adapts to the stressor.
Negative (physiological) symptoms improve or even disappear. The resistance that the person shows is greater for the harmful agent and less for stimuli other than this.
Again, two things can happen here: whether or not the situation is overcome. If it is overcome, the general adaptation syndrome ends, and if it is not overcome, the third and final phase occurs: the exhaustion phase.
3. Exhaustion phase
At this point, the resources are exhausted. The individual loses the ability to adapt to the stressor, Which is usually severe and prolonged. The symptoms of the alarm phase reappear.
It is at this stage that the individual is most vulnerable to the disease. In addition, this phase is not irreversible, except in extreme cases, and the person will need a period of rest to recover the reservations.
If we go to the origin of the general adaptation syndrome, we find the experiences developed by Hans Selye. These focused on the discovery of a new sex hormone. To do this, he injected the ovary extract into rats and analyzed the results, which allowed him to observe a consistency in the changes produced.
These changes included, among others, an enlarged adrenal cortex, atrophy of the endothelial reticular system, and the development of gastric and duodenal ulcers. Outraged, the magnitude of these changes was proportional to the amount of ovarian extract injected.
Selye introduced different substances to the rats, and they all produced the same effect.
A few years later, while training as a doctor at the University of Prague, he had his first contact with patients. He found many they complained of general symptoms such as fever, headache, weight loss… and that these symptoms were independent of the disease they were suffering from.
The term stress
So, Selye called this effect the “just being sick” syndrome, and linked the concept to the findings found in rats, which also reacted equally to different substances.
Years later, Selye defined the condition in which the body reacts to harmful agents (stressors) with the term stress (meaning tension, pressure, coercion).
The concept of stress was quickly adopted and used around the world, With its relevant adaptations.
- Bertola, D. (2010). Hans Selye and his stressed rats. University medicine, 12 (47), 142-143
- Amic, I. (2012). Manual of Health Psychology. Madrid: Pyramid.