stress

A stressor is a chemical or biological agent, environmental condition, external stimulus or an event that causes stress to an organism.An event that triggers the stress response may include:

environmental stressors (hypo or hyper-thermic temperatures, elevated sound levels, over-illumination, overcrowding)
daily stress events (e.g., traffic, lost keys, money, quality and quantity of physical activity)
life changes (e.g., divorce, bereavement)
workplace stressors (e.g., high job demand vs. low job control, repeated or sustained exertions, forceful exertions, extreme postures)
chemical stressors (e.g., tobacco, alcohol, drugs)
social stressor (e.g., societal and family demands)Stressors have physical, chemical and mental responses inside of the body. Physical stressors produce mechanical stresses on skin, bones, ligaments, tendons, muscles and nerves that cause tissue deformation and in extreme cases tissue failure. Chemical stresses also produce biomechanical responses associated with metabolism and tissue repair. Physical stressors may produce pain and impair work performance. Chronic pain and impairment requiring medical attention may result from extreme physical stressors or if there is not sufficient recovery time between successive exposures.Stressors may also affect mental function and performance. One possible mechanism involves stimulation of the hypothalamus, CRF (corticotropin release factor) -> pituitary gland releases ACTH (adrenocorticotropic hormone) -> adrenal cortex secretes various stress hormones (e.g., cortisol) -> stress hormones (30 varieties) travel in the blood stream to relevant organs, e.g., glands, heart, intestines -> flight-or-fight response. Between this flow there is an alternate path that can be taken after the stressor is transferred to the hypothalamus, which leads to the sympathetic nervous system. After which, the adrenal medulla secretes epinephrine. Mental and social stressors may affect behavior and how individuals respond to physical and chemical stressors.
Life requires everyone to make sudden and planned adjustments to meet its demands, but the greater the demand comes with a greater adjustment and possibly more stress. Determining the impact of these various stressors allow individuals to decide the relationship between the types of stressors and the degree of distress. Identifying the stressor-stress relationship must involve quantifying the impact of life demands and all stress spurred from it. To do this, subjective measures and objective measures will be used depending on the situation. Individuals determine the degree of adjustment themselves in subjective measures, but a degree of adjustment will be or has already been assigned to the individual in an objective measure. The degrees of adjustment are measured by life change units, where one unit equals a degree of adjustment necessary to cope with the life change. The practice of measuring life change units led to the creation of many scales composed of these units that are tailored to certain life events or situations, such as social readjustment and college students .
Once the relationship between the stressor (event) and the stress, the individual can then begin to focus on the stress magnitude and the stress itself. For life events with a lower magnitude of impact, the ability to cope and adjust may not be very complex and relatively brief. But for others, life events with high magnitudes can impact their lives in many ways for an extended amount of time. The various stressors listed above can all have events or stressors that range anywhere from minor to traumatic. Traumatic events are very debilitating stressors, and often times these stressors are uncontrollable. Traumatic events can deplete an individual's coping resources to an extent where the individual may develop acute stress disorder or even post-traumatic stress disorder. Acute stress disorder is a psychological disorder where a traumatic event that is life threatening or threatens an injury causes a reaction of fear and helplessness lasting up to four weeks. Post-traumatic stress disorder has symptoms of lasting longer than one month, and the first symptom is a history of experiencing a traumatic event followed with a reaction of intense fear, helplessness, or horror. The traumatic event is persistently reexperienced in one of these ways: recurrent distressing recollections, dreams, flashbacks, illusions, or a sense of reliving the experience, and distress or physical arousal by reminders of this event. The individual suffers from a persistent avoidance of reminders of the event. People who have been abused, victimized, or terrorized are often more susceptible to stress disorders .
No matter the magnitude of the stressor and stress, most stressor-stress relationships can be evaluated and determined by either the individual or a psychologist. Without proper attention, stress can produce severe effects on mental health and the immune system, which can eventually lead to effects on the physical body. Therapeutic measures are often taken to help replenish and rebuild the individual's coping resources while simultaneously aiding the individual in dealing with the current stressor.

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