Outline the main features of Selye's General Adaptation Syndrome.

Selye described three stages to the physical response to stress which he called the General Adaptation Syndrome or GAS:
The alarm stage - the stressor is perceived, causing the release of and activation of the autonomic nervous system. This leads to the release of hormones such as adrenaline, noradrenaline and from the adrenal glands. These hormones cause an increase in heart rate, blood pressure and . They also cause the mobilization of reserves (glucose is released into the bloodstream). This stage has been termed the 'fight or ' reaction.
The stage - during this stage, the body begins to adapt to the stressor. Release of adrenaline and noradrenaline is , but still stay higher than normal. Heart rate, blood and blood sugar levels return to normal.
The stage - if the stressor is long-lasting, effects of the prolonged drain on the body's resources begin to cause problems such as raised blood pressure, and depression. The body's tissue and organs are damaged - this stage is associated with diseases of or stress related illnesses.