Stress, Theory and Physiology of

Stress is a normal and necessary aspect of human life. Although the term stress has multiple meanings in colloquial speech, in biomedical studies it refers to novel, ego-involving experiences in which the individual perceives lack of control and the possibility of negative consequences. An individual's reaction to stress is related to his or her genetic makeup and life history, and it is well-known that different individuals may show quite different responses to the same stressful situation, with one adapting successfully (in fact, some people deliberately put themselves in stressful situations because it brings out their best performance) while another may experience long-term psychological [Page 1070]or emotional problems in response. Formal studies of human response to stress have been pursued at least since the early 20th ...