<P> The fight - or - flight response ( also called 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 , preparing 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 , as well as the neurotransmitters dopamine and serotonin , also affect how organisms react to stress . </P>
what happens to the body during the fight or flight response
the adrenal medulla produces a hormonal cascade that results in the secretion of catecholamines , especially norepinephrine and epinephrine