What Stress Does to the Body

Abstract

Stress is thought to be an important factor in many health problems. Early stress researchers found that regardless of the environmental stressor, a generalized physiological response was activated in the organism called the "fight or flight," or stress response and termed the General Adaptation Syndrome by Hans Selye. When an individual encounters a stressor, the body part that first notes the stimulus passes the signal to the brain. The message passes through the reticular activating system to the hypothalamus and thalamus. When the hypothalamus experiences the stressor signal, it simultaneously activates the two major stress pathways: the autonomic nervous system and the endocrine system. When the sympathetic part of the autonomic nervous system is activated by the hypothalamus, involuntary functions such as heart rate, blood pressure, respiration, and body fluid regulation are affected. At the same time, the pituitary gland is stimulated, which in turn orders the release of several chemical hormones. The chemical cortisol provides fuel for the "fight or flight" response by increasing blood sugar so that there is energy for action. Aldosterone increases the blood pressure. Epinephrine (adrenaline) and norepinephrine are also produced, along with thyroxine.