Canadian medical researcher Hans Selye first gave us insight into stress reactions more than fifty years ago. Irrespective of the source of stress, the body mobilizes its defenses to deal with the threat in a certain pattern. Selye referred to this pattern as the General Adaptation Syndrome (GAS).
The GAS consists of three stages. Selye called these the alarm stage, the stage of resistance, and the stage of exhaustion.
1. The Alarm Reaction
The alarm reaction consists of two phases. These are:
- Shock phase
- Counter-shock phase
During the shock phase, the body automatically tries to defend itself. The defence involves both the autonomic nervous system and the endocrine system. The sympathetic division of the autonomic nervous system becomes energized. It increases heart rate and blood pressure, diverts blood away from digestive organs and into the skeletal muscles, and increases perspiration. The endocrine system goes into emergency action. The adrenal glands especially show significant changes. The adrenal cortex becomes enlarged, and produces large amount of stress hormone epinephrine. It also releases its stored-up supply of the hormones known as steroids. These hormones aid the action of the autonomic nervous system and increase levels of blood sugar.
In the counter-shock phase, the body temporarily recovers from the symptoms.
2. The Stage of Resistance
If the stressor persists, people move into the next stage of the GAS. Selye called this the stage of resistance. The adrenal glands return to their normal size. The glucose and salt levels of the blood are restored.
During the second stage of the GAS, the body’s resources have been fully mobilized, and resistance is costly. If an individual is faced with a new stress psychological or physical-his body is less able to deal with it.
3. The Stage of Exhaustion
The stage of resistance does not last indefinitely. If the stressor continues for a long time, the body’s resources may not be sufficient to deal with it. In that case, the body enters the phase of exhaustion. Once again, the adrenal glands become enlarged, the kidneys get damaged, and serious physical changes may occur in the brain. The result is illness.
If the person faces a second stressor when he has already entered the GAS, the progress towards the stage of exhaustion is much more rapid.