Activation of the sympathetic adrenal medullary axis.
Bodily changes that occur when a threat is perceived; acts as a survival mechanism.
in certain animals, a reaction necessary for survival. When confronted with danger, the animal prepares to either fight or flee. As a result of this evolutionary heritage, the fight-or-flight response in humans today is a physiological reaction to stressful situations.
A pattern of bodily responses that prepares the organism for an emergency. Most of these physiological changes result from activation of the sympathetic system and the adrenalcortical system. Includes increases in pupil size, heart rate, blood pressure, respiration, muscle tension, and the secretion of epinephrine, norepinephrine, ACTH and other hormones; decreases in saliva, mucous, digestive activity, and the size of blood vessels. See also ACTH, adrenal-cortical system, epinephrine, norepinephrine, sympathetic system.
The fight-or-flight response, also called the acute stress response, was first described by Walter Cannon in 1929. His theory states that animals react to threats with a general discharge of the sympathetic nervous system, priming the animal for fighting or fleeing. This response was later recognized as the first stage of a general adaptation syndrome that regulates stress responses among vertebrates and other organisms.
