Endocrine System


What is the hormonal response to stress?

The stress response, also known as the general adaptation syndrome (GAS), has three basic phases: 1) the alarm phase, 2) the resistance phase, and 3) the exhaustion phase. The alarm phase is an immediate reaction to stress. Epinephrine is the dominant hormone of the alarm phase. It is released in conjunction with the sympathetic nervous system and produces the “fight or flight” response. Nonessential body functions such as digestive, urinary, and reproductive activities are inhibited.

The resistance phase follows the alarm phase if the stress lasts more than several hours. Glucocorticoids are the dominant hormones of the resistance phase. Endocrine secretions coordinate three integrated actions to maintain adequate levels of glucose in the blood. They are: 1) the mobilization of lipid and protein reserves, 2) the conservation of glucose for neural tissues, and 3) the synthesis and release of glucose by the liver.

If the body does not overcome the stress during the resistance phase, the exhaustion phase begins. Prolonged exposure to high levels of hormones involved in the resistance phase leads to the collapse of vital organ systems. Unless there is successful intervention and it can be reversed, the failure of an organ system will be fatal.


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