Why is the bodys response to stress called the fight or flight response?
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Alternate titles: defense reaction By The Editors of Encyclopaedia Britannica Last Updated: Dec 19, 2022 Article History Table of Contentsautonomic nervous system See all media Related Topics:stimulus-response behaviour...(Show more) See all related content → fight-or-flight response, response to an acute threat to survival that is marked by physical changes, including nervous and endocrine changes, that prepare a human or an animal to react or to retreat. The functions of this response were first described in the early 1900s by American neurologist and physiologist Walter Bradford Cannon. Discover how the various parts of the brain play a key role in controlling the fear response through the release of chemicals See all videos for this articleWhen a threat is perceived, the sympathetic nerve fibres of the autonomic nervous system are activated. This leads to the release of certain hormones from the endocrine system. In physiological terms, a major action of these hormones is to initiate a rapid, generalized response. This response may be triggered by a fall in blood pressure or by pain, physical injury, abrupt emotional upset, or decreased blood glucose levels (hypoglycemia). The fight-or-flight response is characterized by an increased heart rate (tachycardia), anxiety, increased perspiration, tremour, and increased blood glucose concentrations (due to glycogenolysis, or breakdown of liver glycogen). These actions occur in concert with other neural or hormonal responses to stress, such as increases in corticotropin and cortisol secretion, and they are observed in some humans and animals affected by chronic stress, which causes long-term stimulation of the fight-or-flight response. In addition to increased secretion of cortisol by the adrenal cortex, activation of the fight-or-flight response causes increased secretion of glucagon by the islet cells of the pancreas and increased secretion of catecholamines (i.e., epinephrine and norepinephrine) by the adrenal medulla. The tissue responses to different catecholamines depend on the fact that there are two major types of adrenergic receptors (adrenoceptors) on the surface of target organs and tissues. The receptors are known as alpha-adrenergic and beta-adrenergic receptors, or alpha receptors and beta receptors, respectively (see human nervous system: Anatomy of the human nervous system). In general, activation of alpha-adrenergic receptors results in the constriction of blood vessels, contraction of uterine muscles, relaxation of intestinal muscles, and dilation of the pupils. Activation of beta-receptors increases heart rate and stimulates cardiac contraction (thereby increasing cardiac output), dilates the bronchi (thereby increasing air flow into and out of the lungs), dilates the blood vessels, and relaxes the uterus. Why is it called the fight or flight response?The term 'fight-or-flight' represents the choices that our ancient ancestors had when faced with danger in their environment. They could either fight or flee. In either case, the physiological and psychological response to stress prepares the body to react to the danger.
What is the fight or flight response called?The fight-or-flight or the fight-flight-or-freeze response (also called hyperarousal or the acute stress response) is a physiological reaction that occurs in response to a perceived harmful event, attack, or threat to survival. It was first described by Walter Bradford Cannon.
What happens to the body during the fightYour heart rate and blood pressure increase.
Your blood flow is being redirected so you might experience feeling cool or like your hands and feet are cold and clammy. Your face might also appear flushed as blood and hormones circulate throughout your body. Blunt pain response is compromised.
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