Stress is a biological term which refers to the consequences of the failure of a human or animal body to respond appropriately to emotional or physical threats to the organism, whether actual or imagined.

It includes a state of alarm and adrenaline production, short-term resistance as a coping mechanism, and exhaustion. It refers to the inability of a human or animal body to respond. Common stress symptoms include irritability, muscular tension, inability to concentrate and a variety of physical reactions, such as headaches and accelerated heart rate.]

 It covers a huge range of phenomena from mild irritation to the kind of severe problems that might result in a real breakdown of health.

Neurochemistry and physiology

The neurochemistry of the stress response is now believed to be well understood, although much remains to be discovered about how the components of this system interact with one another, in the brain and throughout in the body. In response to a stressor, corticotropin-releasing hormone (CRH) and arginine-vasopressin (AVP) are secreted into the hypophyseal portal system and activate neurons of the paraventricular nuclei (PVN) of the hypothalamus. The locus ceruleus and other noradrenergic cell groups of the adrenal medulla and pons, collectively known as the LC/NE system, also become active and use brain epinephrine to execute autonomic and neuroendocrine responses, serving as a global alarm system.

The autonomic nervous system provides the rapid response to stress commonly known as the fight-or-flight response, engaging the sympathetic nervous system and withdrawing the parasympathetic nervous system, thereby enacting cardiovascular, respiratory, gastrointestinal, renal, and endocrine changes. The hypothalamic-pituitary-adrenal axis (HPA), a major part of the neuroendocrine system involving the interactions of the hypothalamus, the pituitary gland, and the adrenal glands, is also activated by release of CRH and AVP. This results in release of adrenocorticotropic hormone (ACTH) from the pituitary into the general bloodstream, which results in secretion of cortisol and other glucocorticoids from the adrenal cortex. These corticoids involve the whole body in the organism's response to stress and ultimately contribute to the termination of the response via inhibitory feedback.]

Stress can significantly affect many of the body's immune systems, as can an individual's perceptions of, and reactions to, stress. The term psychoneuroimmunology is used to describe the interactions between the mental state, nervous and immune systems, as well as research on the interconnections of these systems. Chronic stress has also been shown to impair developmental growth in children by lowering the pituitary gland's production of growth hormone, as in children associated with a home environment involving serious marital discord, alcoholism, or child abuse.

Common sources

Both negative and positive stressors can lead to stress. Some common categories and examples of stressors include: sensory input such as pain, bright light, or environmental issues such as a lack of control over environmental circumstances, such as food, housing, health, freedom, or mobility. Social issues can also cause stress, such as struggles with nonspecific or difficult individuals and social defeat, or relationship conflict, deception, or break ups, and major events such as birth and deaths, marriage, and divorce. Life experiences such as poverty, unemployment, depression, obsessive compulsive disorder, heavy drinking, online places such as MySpace, or insufficient sleep can also cause stress. Students and workers may face stress from exams, project deadlines, and group projects.

Adverse experiences during development (e.g. prenatal exposure to maternal stress, poor attachment histories, sexual abuse) are thought to contribute to deficits in the maturity of an individual's stress response systems. O

Stress management

Responses to stress include adaptation, psychological coping such as stress management, anxiety, and depression. Over the long term, distress can lead to diminished health or illness; to avoid this, stress must be managed. Stress management encompasses techniques intended to equip a person with effective coping mechanisms for dealing with psychological stress, with stress defined as a person's physiological response to an internal or external stimulus that triggers the fight-or-flight response. Stress management is effective when a person utilizes strategies to cope with or alter stressful situations. There are several ways of coping with stress, such as controlling the source of stress or learning to set limits and to say "No" to some demands that bosses or family members may make.