BIOLOGICAL EFFECTS OF STRESS
Imagine one of those old movies where the cavemen are get attacked by a saber toothed tiger, or even a dinosaur. In that prehistoric moment, the caveman has only two options, life or death. There is no other possible outcome. In a life or death situation the body will do anything it can do to live, even at the expense of it's own health. Therefore, in that moment, profound changes take place that change individual biochemistry to maximize chance of immediate survival. This is called the "fight or flight," response.
The sympathoadrenalmedullary system is the stress pathway involved with acute stress. This is when the higher brain centres have evaluated a situation to be stressful which triggers the hypothalamus, which activates the sympathetic branch of the autonomic nervous system (ANS). This then triggers the adrenal medulla to release adrenaline and nor adrenaline into the bloodstream to provide us with energy. When this branch has been activated we see such symptoms as increased heart rate, heavier and faster rate of respiration and sweaty palms.
The other bodily response is called the pituitary adrenal pathway and this deals with chronic stress. Once the brain centres are alarmed to stress in the pathway (stressors) the hypothalamus triggers the pituitary gland which releases ACTH into the bloodstream to stimulate the adrenal cortex to release a substance known as cortisol into the bloodstream. The function of cortisol is to maintain a steady supply of blood sugar for continued energy. This enable the body to cope with the stressor..