Stress (medicine)

Stress is a medical term for a wide range of strong external stimuli, both physiological and psychological, which can cause a physiological response called the general adaptation syndrome.  The use of the term stress in serious and recognized cases, such as those of post-traumatic stress disorder and psychosomatic illness.  Sympathetic nervous output produces the fight-or-flight response, causing the body to divert bloodflow to large muscles as the body prepares to run away from or fight something. Modern stressors can cause continual sympathetic nervous system activation with very little opportunity for the parasympathetic nervous system to activate. When the parasympathetic system is active, the bowel and other non-muscle organs receive good blood-flow, the pupils constrict, and the glands all function well and secrete their various compounds.