ABSTRACT
Many people conceptualize stress as external to the body, but we define stress as an internal process involving normal physical responses of the body to challenging stimuli. Two pioneering scientists, Walter Cannon and Hans Selye, developed stress theory. Trained in different disciplines, both demonstrated the profound influence of fear, anger, and helplessness on the body. Walter Cannon's work was influenced by Claude Bernard, a French physiologist, who theorized, "One of the most characteristic features of all living beings is their ability to maintain the constancy of their internal milieu, despite changes in the surroundings." Somatotrophin (STH), also called growth hormone, elevates glucose and lipids in the blood under conditions of emotional arousal, exertion, cold exposure, trauma, or hypoglycemia. Some hormones decrease under stress, including follicle stimulating hormone (FSH) and luteinizing hormone (LH), leading to lowered female fecundity.
