Neurobiological Foundations of Stress.

Modern understanding of stress stems from classic work in the 1930s by Hans Selye, who developed the notion of the general adaptation syndrome (Selye, 1936). Selye posited that the body shows a common, integrated set of responses in an attempt to adapt to many different kinds of stress. Until his work, many scientists viewed different kinds of stress as having different effects on the body; for example, the effect of exposure to severe cold was thought to be very different from the effect of blood loss. Indeed, each particular type of stressor does have unique effects. However, Selye showed that different severe stressors also have common features. He identified three stages. First is the shock (or alarm) phase, involving decreased blood pressure, body temperature, and muscle tone (the reader has no doubt experienced at least some degree of shock following a minor or not so minor injury, particularly if blood loss occurred). Selye termed the second phase of the adaptation response the stage of resistance, when the body fights back. If the stress is severe and continues for a long period, the body defenses break down and the third stage, exhaustion, ensues. Among other things, this stage includes a marked impairment of the immune system. [ABSTRACT FROM AUTHOR]