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Stress is a person's response to a stressor such as an environmental condition or a stimulus. Stress is a body's method of reacting to a challenge.

According to the stressful event, the body's way to respond to stress is by sympathetic nervous system activation which results in the fight-or-flight response. Stress typically describes a negative condition or a positive condition that can have an impact on a person's mental and physical well-being.

The term stress had none of its contemporary connotations before the 1920s. It is a form of the Middle English destresse, derived via Old French from the Latin stringere, "to draw tight."[1] The word had long been in use in physics to refer to the internal distribution of a force exerted on a material body, resulting in strain. In the 1920s and 1930s biological and psychological circles occasionally used the term to refer to a mental strain or to a harmful environmental agent that could cause illness. Walter Cannon used it in 1926 to refer to external factors that disrupted what he called homeostasis.[2] But "[...] Stress as an explanation of lived experience is absent from both lay and expert life narratives before the 1930s".[3]
Homeostasis is a concept central to the idea of stress. In biology, most biochemical processes strive to maintain equilibrium, a steady state that exists more as an ideal and less as an achievable condition. Environmental factors, internal or external stimuli, continually disrupt homeostasis; an organism’s present condition is a state of constant flux moving about a homeostatic point that is that organism’s optimal condition for living. Factors causing an organism’s condition to diverge too far from homeostasis can be experienced as stress. A life-threatening situation such as a physical insult or prolonged starvation can greatly disrupt homeostasis. On the other hand, an organism’s effortful attempt at restoring conditions back to or near homeostasis, often consuming energy and natural resources, can also be interpreted as stress. In such instances, an organism’s fight-or-flight response recruits the body's energy stores and focuses attention to overcome the challenge at hand.[citation needed]
The ambiguity in defining this phenomenon was first recognized by Hans Selye (1907-1982) in 1926.

Stress (biology) Walter Cannon used it in 1926 to refer to external factors that disrupted what he called homeostasis.[2] But "...stress as an explanation of lived experience is absent from both lay and expert life narratives before the 1930s".[3] Physiological stress represents a wide range of physical responses that occur as a direct effect of a stressor causing an upset in the homeostasis of the body.

Stress (biology)

Upon immediate disruption of either psychological or physical equilibrium the body responds by stimulating the nervous, endocrine, and immune systems. The reaction of these systems causes a number of physical changes that have both short and long term effects on the body. Use of the word Stress. Biological background. Stress (psychological) In psychology, stress is a feeling of strain and pressure.

Stress (psychological)

Small amounts of stress may be desired, beneficial, and even healthy. Positive stress helps improve athletic performance. It also plays factor in motivation, adaptation, and reaction to the environment. Excessive amounts of stress however, may lead to many problems in the body that could be harmful. Stress can be external and related to the environment,[1] but may also be created by internal perceptions that cause an individual to have anxiety or other negative emotions surrounding a situation, such as pressure, discomfort, etc., which they then deem stressful. Humans experience stress, or perceive things as threatening, when they do not believe that their resources for coping with obstacles (stimuli, people, situations, etc.) are enough for what the circumstances demand.

Defense physiology. Defense physiology is a term used to refer to the symphony of body function (physiology) changes which occur in response to a stress or threat.

Defense physiology

When the body executes the “fight-or-flight" reaction or stress response, the nervous system initiates, coordinates and directs specific changes in how the body is functioning (physiology), preparing the body to deal with the threat. (See also General Adaptation Syndrome.) Trier social stress test. Sketch of the administration of the Trier Social Stress Test History[edit] Psychosocial stress is associated with a variety of biomarkers, such as salivary and blood serum cortisol, prolactin, human growth hormone (hGH), adrenocorticotropic hormone (ACTH), and heart rate.[1] Prior to 1993, a number of laboratory tasks were used to elicit these stress markers for research, including the cold pressor test, the Stroop test, public speaking, and others.[2] These studies encountered two problems: First, there was large interindividual variability in the physiological response to stress, and second, the methods previously used tended to produce effects that were too small to be reliably measured.

Trier social stress test

Consequently, the results from these studies tended to be inconsistent and unreliable.[1] In the years since, the TSST has been widely used in stress research. Holmes and Rahe stress scale. Development[edit] In 1967, psychiatrists Thomas Holmes and Richard Rahe examined the medical records of over 5,000 medical patients as a way to determine whether stressful events might cause illnesses.

Holmes and Rahe stress scale

Patients were asked to tally a list of 43 life events based on a relative score. A positive correlation of 0.118 was found between their life events and their illnesses. Their results were published as the Social Readjustment Rating Scale (SRRS),[1] known more commonly as the Holmes and Rahe Stress Scale. Subsequent validation has supported the links between stress and illness.[2] Supporting research[edit]


Neurochemistry. Biological mechanisms. Psychological concepts. Clinical symptoms and disorders.