"Stress like relativity, is a scientific concept which has suffered from the mixed blessing of being too well known and too little understood," says Dr. Hans Selye.

It is an old observation that stress or tension by itself can produce different diseases in man. People are known to have gone mad in a situation of extreme mental stress. They are also known to have died suddenly, obviously because of a heart attack. Yet it is not very long ago that the scientific proof of how it happens became known.
Stress Syndrome

In 1936, Dr. Hans Selye while doing research at the McGill University in Canada, made extracts of the ovaries of the female rats in order to study the effect of its hormones. He injected a new extract into female rats whose ovaries had already been removed. The results were as unexpected as they were bafiling. He found the adrenal glands greatly swollen, the lymph nodes degenerated, and ulcers in the stomach and intestines. The whole body had in a way become a wreck.

He thought that he had inadvertently introduced a toxic material in the extracts that he had injected. Then he injected, instead of the extract, a solution of a known toxic substance, formaldehyde. It produced a similar effect in the rats.

In spite of the said results, he was not entirely convinced that the effects were due to the injection of a toxic material. Could such effects be produced by other means? He kept his rats in the extreme cold on the roof top of his laboratory. Some of these rats lived for quite some time, but ultimately succumbed to such a treatment. Another batch of rats was put in motor-dri­ven revolving cages and they ultimately died of exhaus­tion. Both the above groups of rats showed- effects in their internal organs similar to those observed after the injection of the new ovarian extract or the injection of formaldehyde.

A picture emerged: an injection of an ovarian ext­ract or of formaldehyde, or exhaustion due to prolong­ed cold or to prolonged exertion-the latter two acting only as non-specific stress-killed rats producing a picture of swollen adrenals, degenerated lymphatic system and stomach ulcers.

It became obvious to him that the effects produced in different organs were the result of the stress which the animals experienced in all these different situations. He still had to confirm his hypothesis.

By that time it was known that the pituitary con­trolled the action of different other hormonal glands, including those of the-ovaries and the adrenals. Hans Selye thought that tampering with the pituitary might provide a clue to the action of the ovarian extract and thus explain the mode of action of stress upon the body.

He removed the pituitary glands in the rats and then repeated the above experiments. This time no damage occurred. Next, he removed the adrenals but left the pituitary and then repeated the experiments. The body was damaged, though less than with the initial experiments. From these experiments, Selye concluded that stress produced its effect upon the body through the pituitary and the adrenals.

Such an effect occurred only in those rats who sur­vived long enough in these experiments. Those who died much sooner did not develop such lesions.

Further experiments showed that wired an animal was put under stress, its body responded immediately to it by making certain changes in its activities. When the stress was continued, these changes became a regular feature. And if the animal remained under stress for a prolonged time, these changes exhausted the body and ultimately caused its death.

To the initial response, Selye gave the name Alarm Reaction as it 'represented the bodily expression of a generalized call to arms of the defensive forces in the organism'. The next phase he called the Stage of Resis­tance as in this the animal adapted itself to the stress­ producing environments. The last phase, he called the Stage of Exhaustion as in this the animal showed signs of premature wear and tear.

The entire syndrome, including its pattern of development in time, was called the General Adaptation Syndrome.

Alarm Reaction is the body's response when it is suddenly exposed to stimuli to which it is not adapted. This reaction has' two phases:

Shock Phase. It is the initial and immediate reac­tion to the noxious stimulus. Various signs of injury such as rapid pulse rate, decreased temperature, lower blood pressure and loss of muscle tone, are typical symptoms.

Counter Phase. This is-a rebound reaction marked by the mobilization of defensive forces of the body, .during which the adrenal cortex is enlarged.

The Stage of Resistance is when the person's full adaptation to the stress and the consequent improvement or disappearance of the symptoms occur. At this stage, however, there is a concurrent decrease in resistance to fresh noxious stimuli and stress.

The Stage of Exhaustion sets in if the stress is sufficiently severe and prolonged because body's adaptability to stress is limited and exhaustion inexorably follows. Various symptoms or diseases appear and if stress is unabated, death follows.

Selye's researches showed that stress or tension, particularly if it is prolonged, is very harmful to the body.