GENERAL ADAPTATION SYNDROME (GAS)

General adaptation syndrome, or GAS, is a term used by doctors to describe the body's short-term and long-term reactions to stress. Broken down the term can be analyzed such that:

General - responses are produced only by agents which have a general effect upon large portions of the body.

Adaptive – the body reacts to stimulate a defense.

Syndrome – the individual responses manifested are coordinated and/or dependent on each other.

Originally described by Hans Selye (1907-1982), an Austrian-born physician who immigrated to Canada in 1939, the general adaptation syndrome represents a three-stage reaction to stress. The alarm reaction (AR), the stage of resistance (SR), and the stage of exhaustion (SE).

Selye believed that the general adaptation syndrome involved two major systems of the body, the nervous system and the endocrine (or hormonal) system. He then outlined the three distinctive stages in the syndrome's evolution.

Stage 1: Alarm reaction (AR)
In the first stage of GAS, the body releases adrenaline and a variety of other psychological mechanisms to combat the stress and to stay in control. This is called fight or flight response. The muscles tense, the heart beats faster, the breathing and perspiration increases, the eyes dilate, the stomach may clench. This all begins when hypothalamus secretes two neurohormones - corticotropin-releasing hormone(CRH) and thyrotropin-releasing hormone(TRH) which stimulate the pituitary gland to produce hormones. In the case of stress the pituitary influences the work of all glands. For instance the pituitary secretes adrenocorticotropic hormone(ACTH) which stimulates the adrenal glands to secrete corticoids: adrenaline, noradrenaline, cortisone, and cortisol. The thyroid gland is stimulated by the thyroid-stimulating hormone(TSH) to secrete thyroxine. Another hormone secreted isgonadotrophin which stimulates the reproductive glands to produce less hormones. The secretion of corticoids is most characteristic of the stress response. The adrenal gland is stimulated also by the nervous system, which arouses reaction immediately. Adrenaline and noradrenaline are the hormones which cause quicker heart rate, higher blood pressure, more frequent breathing. Cortisol and cortisone suppress the immune system. Believe it or not, this is done by nature to protect you in case something bad happens. Once the cause of the stress is removed, the body will go back to normal.

Stage 2: Stage of resistance (SR)
The second stage is the body’s response to long term protection. It secretes further hormones that increase blood sugar levels to sustain energy and raise blood pressure. The adrenal cortex produces hormones called corticosteroids for this resistance reaction. Overuse by the body's defense mechanism in this phase eventually leads to disease. If this adaptation phase continues for a prolonged period of time without periods of relaxation and rest to counterbalance the stress response, sufferers become prone to fatigue, concentration lapses, irritability and lethargy as the effort to sustain arousal slides into negative stress.

Stage 3: Stage of exhaustion (SE)
By the third stage of GAS the body has run out of its reserve of body energy and immunity. Mental, physical and emotional resources suffer heavily. The body experiences "adrenal exhaustion". The blood sugar levels decrease as the adrenals become depleted, leading to decreased stress tolerance, progressive mental and physical exhaustion, illness and death. Otherwise, the organism recovers fully in the course of time. Prolonged, too frequent, or too strong, hyper-stress reactions can cause permanent disorders to the body or to the psyche.

The general adaptation syndrome is also influenced by such universal human variables as overall health and nutritional status, sex, age, racial background, level of education, socioeconomic status (SES), genetic makeup, etc. Some of these variables are biologically based and difficult or impossible to change.