fight-or-flight reaction

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A set of physiological changes, such as increases in heart rate, arterial blood pressure, and blood glucose, initiated by the sympathetic nervous system to mobilize body systems in response to stress.

The set of processes that occur in the body when it is confronted with some form of physical or mental stress. For example, if a person is faced with danger (as from a vicious animal about to attack), the nervous system signals for adrenaline and other hormones to be released into the blood. These hormones prepare the body either to confront the attacking animal or to flee to safety (thus, “fight or flight”). Changes in the body include increased heart rate, dilated pupils of the eye (to improve vision), and increased supply of blood to the muscles (to prepare the body for action).

A set of physiological changes, such as increases in heart rate, arterial blood pressure, and blood glucose, initiated by the sympathetic nervous system to mobilize body systems in response to stress. Also called emergency theory.

Coordinated result of increased secretion of adrenal medullary hormones and of stimulation and resulting increased activity of the sympathetic nervous system. Creates the optimum situation for the survival of the individual by fighting the adversary or fleeing from it. The reaction comprises constriction of the blood vessels of alimentary tract and skin but dilatation of those to skeletal muscles; increased cardiac rate and output, and coronary dilatation occur; also elevation of the blood sugar levels and metabolic rate, dilatation of the pupils, evacuation of blood from the spleen, bronchodilatation, piloerection and decrease in coagulation time.