FIGHT OR FLIGHT

The fight-or-flight response (also called the fight, flight, freeze, or fawn response in post-traumatic stress disorder, 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. 
This response is recognized as the first stage of the General Adaptation Syndrome that regulates stress responses among vertebrates and other organisms.

We actually live in a world where this response can be charged as a crime.....let that sink in.