Stress is the body's adaptive response to abnormal circumstances. A person in a physically or mentally demanding or dangerous situation is said to be under stress. Internal medical and mental disorders can also produce stress responses. Chronic repetition of certain emotions such as anger or despair, changes in work or home situations, or reactions to surgery are just a few of the other ways in which stress can occur. More than one stress-causing factor can be present at a time.
Physiological effects linked with stress include ulcers, high blood pressure, and heart disease.
Stress can also adversely affect the immune system, causing the body to be less resistant to a wide range of other health problems. The effects of stress can be complex, but they all involve a certain group of basic body responses. These responses arose in the course of evolution, as organisms met situations of physical danger. This in turn triggers the adrenal glands to release epinephrine and various other hormones that speed up the heart rate, raise blood pressure, and increase muscle tension. We observe these same effects in certain social, emotional or occupational situations, however inappropriate they may be in such circumstances.