The
fight-or-flight response (also called the
fight, flight, freeze, or fawn response [in
PTSD],
hyperarousal, or the
acute stress response) is a physiological reaction that occurs in response to a perceived
harmful event,
attack, or threat to survival. It was first described by
Walter Bradford Cannon. His theory states that animals react to threats with a general discharge of the
sympathetic nervous system, priming the animal for fighting or fleeing. More specifically, the
adrenal medulla produces a hormonal cascade that results in the secretion of
catecholamines, especially
norepinephrine and
epinephrine. The hormones
estrogen,
testosterone and
cortisol, and the neurotransmitters
dopamine and
serotonin, also affect how organisms react to stress.
