Stress is a term in psychology and biology, borrowed from physics and engineering and first used in the biological context in the 1930s, which has in more recent decades become commonly used in popular parlance. It refers to the consequence of the failure of an organism—human or other animal—to respond adequately to mental, emotional, or physical demands, whether actual or imagined. When the person perceives a threat, their nervous system responds by releasing a flood of stress hormones, including adrenaline and cortisol. These hormones rouse the body for emergency action. The stress response is the body’s way of protecting the person. When working properly, it helps in staying focused, energetic, and alert.
Signs of stress may be cognitive, emotional, physical, or behavioral.
Inability to concentrate
Seeing only the negative
Anxious or racing thoughts
Irritability or short temper
Agitation, inability to relax
Sense of loneliness and isolation
Depression or general unhappiness
Aches and pains
Diarrhea or constipation
Chest pain, rapid heartbeat
Loss of sex drive
Eating more or less
Sleeping too much or too little
Isolating yourself from others
Procrastinating or neglecting responsibilities
Using alcohol, cigarettes, or drugs to relax
Nervous habits (e.g. nail biting, pacing)
General adaptation syndrome
Physiologists define stress as how the body reacts to a stressor, real or imagined, a stimulus that causes stress. Acute stressors affect an organism in the short term; chronic stressors over the longer term.
Selye researched the effects of stress.
Alarm is the first stage. When the threat or stressor is identified or realized, the body’s stress response is a state of alarm. During this stage, adrenaline will be produced in order to bring about the fight-or-flight response. There is also some activation of the HPA axis, producing cortisol.
Resistance is the second stage. If the stressor persists, it becomes necessary to attempt some means of coping with the stress. Although the body begins to try to adapt to the strains or demands of the environment, the body cannot keep this up indefinitely, so its resources are gradually depleted.
Exhaustion is the third and final stage in the GAS model. At this point, all of the body’s resources are eventually depleted and the body is unable to maintain normal function. The initial autonomic nervous system symptoms may reappear (sweating, raised heart rate, etc.). If stage three is extended, long-term damage may result, as the body’s immune system becomes exhausted, and bodily functions become impaired, resulting in decompensation.
The result can manifest itself in obvious illnesses such as ulcers, depression, diabetes, trouble with the digestive system, or even cardiovascular problems, along with other mental illnesses.
Source and References http://en.wikipedia.org/wiki/Stress_(biology)