Editing Fight-or-flight response (section)

==Physiology ==

===Autonomic nervous system===
{{See also|Autonomic nervous system}}
The autonomic nervous system is a control system that acts largely unconsciously and regulates [[heart rate]], [[digestion]], [[respiratory rate]], [[pupillary dilation|pupillary response]], [[Micturition|urination]], and [[sexual arousal]]. This system is the primary mechanism in control of the fight-or-flight response and its role is mediated by two different components: the sympathetic nervous system and the parasympathetic nervous system.<ref name="Human Physiology - Janig">{{cite book|editor-last=Janig|editor-first=W|title=Human Physiology|year=1989|publisher=Springer-Verlag|location=New York, NY|pages=333–370|author1=Schmidt, A |author2=Thews, G |edition=2|chapter=Autonomic Nervous System}}</ref>

[[File:The Autonomic Nervous System.jpg|thumb|455x455px|Comparison of Sympathetic and Parasympathetic nervous systems]]

====Sympathetic nervous system====
{{See also|Sympathetic nervous system}}
The sympathetic nervous system originates in the [[spinal cord]] and its main function is to activate the arousal responses that occur during the fight-or-flight response.<ref name=":2">{{Cite book |last1=Myers |first1=David G. |title=Psychology |last2=DeWall |first2=C. Nathan |publisher=MacMillan Publishing |year=2021 |edition=13 |pages=422}}</ref> The sympathetic nervous system transfers signals from the dorsal hypothalamus, which activates the heart, increases vascular resistance, and increases blood flow, especially to the muscle, heart, and brain tissues.<ref name=":02">{{Cite journal |last1=Kozlowska |first1=Kasia |last2=Walker |first2=Peter |last3=McLean |first3=Loyola |last4=Carrive |first4=Pascal |date=2015 |title=Fear and the Defense Cascade: Clinical Implications and Management |journal=[[Harvard Review of Psychiatry]] |volume=23 |issue=4 |pages=263–287 |doi=10.1097/HRP.0000000000000065 |issn=1067-3229 |pmc=4495877 |pmid=26062169}}</ref> It activates the adrenal medulla, releasing catecholamines that amplify the sympathetic response. Additionally, this component of the autonomic nervous system utilizes and activates the release of [[norepinephrine]] by the adrenal glands in the reaction.<ref name="Autonomic Nervous System - Chudler2">{{cite web |last=Chudler |first=Eric |title=Neuroscience For Kids |url=http://faculty.washington.edu/chudler/auto.html |access-date=19 April 2013 |publisher=University of Washington}}</ref>

====Parasympathetic nervous system====
{{See also|Parasympathetic nervous system}}
The parasympathetic nervous system originates in the sacral spinal cord and [[Medulla oblongata|medulla]], physically surrounding the sympathetic origin, and works in concert with the sympathetic nervous system. It is known as the calming portion of the autonomic nervous system.<ref name=":22">{{Cite book |last1=Myers |first1=David G. |title=Psychology |last2=DeWall |first2=C. Nathan |publisher=MacMillan Publishing |year=2021 |edition=13 |pages=422}}</ref> While the sympathetic nervous system is activated, the parasympathetic nervous system decreases its response. Efferent [[Vagus nerve|vagal fibers]] originating from the nucleus ambiguous fire in parallel to the respiratory system, decreasing the vagal cardiac parasympathetic tone.<ref name=":03">{{Cite journal |last1=Kozlowska |first1=Kasia |last2=Walker |first2=Peter |last3=McLean |first3=Loyola |last4=Carrive |first4=Pascal |date=2015 |title=Fear and the Defense Cascade: Clinical Implications and Management |journal=[[Harvard Review of Psychiatry]] |volume=23 |issue=4 |pages=263–287 |doi=10.1097/HRP.0000000000000065 |issn=1067-3229 |pmc=4495877 |pmid=26062169}}</ref> After the fight or flight response, the parasympathetic system's main function is to activate the "rest and digest" response and return the body to [[homeostasis]]. This system utilizes and activates the release of the neurotransmitter [[acetylcholine]].<ref name="Autonomic Nervous System - Chudler">{{cite web |last=Chudler |first=Eric |title=Neuroscience For Kids |url=http://faculty.washington.edu/chudler/auto.html |access-date=19 April 2013 |publisher=University of Washington}}</ref>

===Reaction===
The reaction begins in the [[amygdala]], which triggers a neural response in the [[hypothalamus]]. The initial reaction is followed by activation of the [[pituitary gland]] and secretion of the hormone [[Adrenocorticotropic hormone|ACTH]].<ref name="ACTH Action">{{cite web |last=Margioris |first=Andrew |title=ACTH Action on the Adrenal |url=http://www.endotext.org/adrenal/adrenal5/adrenal5.htm |publisher=Endotext.org |access-date=18 April 2013 |author2=Tsatsanis, Christos |date=April 2011 |url-status=dead |archive-url=https://web.archive.org/web/20130306182338/http://www.endotext.org/adrenal/adrenal5/adrenal5.htm |archive-date=6 March 2013 }}</ref> The [[adrenal gland]] is activated almost simultaneously, via the sympathetic nervous system, and releases the hormone [[epinephrine]]. The release of chemical messengers results in the production of the hormone [[cortisol]], which increases [[blood pressure]], [[blood sugar]], and suppresses the [[immune system]].<ref name="physiological reactions - Padgett & Glaser">{{cite journal|last=Padgett|first=David|author2=Glaser, R|title=How stress influences the immune response|journal=Trends in Immunology|date=August 2003|volume=24|issue=8|pages=444–448|doi=10.1016/S1471-4906(03)00173-X|pmid=12909458|citeseerx=10.1.1.467.1386}}</ref>

The initial response and subsequent reactions are triggered in an effort to create a boost of energy. This boost of energy is activated by epinephrine binding to [[cells (biology)|liver cells]] and the subsequent production of [[glucose]].<ref name="Glycogen Metabolism - King">{{cite web |last=King |first=Michael |title=PATHWAYS: GLYCOGEN & GLUCOSE |url=http://neuromuscular.wustl.edu/pathol/diagrams/glycogen.htm |publisher=[[Washington University in St. Louis]]}}</ref> Additionally, the circulation of cortisol functions to turn [[fatty acids]] into available energy, which prepares muscles throughout the body for response.<ref name="Cell Communication in Fight or Flight">{{cite web |title=HOW CELLS COMMUNICATE DURING THE FIGHT OR FLIGHT RESPONSE |url=http://learn.genetics.utah.edu/content/begin/cells/fight_flight/ |publisher=University of Utah |access-date=18 April 2013 |url-status=dead |archive-url=https://web.archive.org/web/20130808004906/http://learn.genetics.utah.edu/content/begin/cells/fight_flight/ |archive-date=8 August 2013 }}</ref>

Catecholamine hormones, such as [[Epinephrine|adrenaline]] ([[epinephrine]]) or [[noradrenaline]] (norepinephrine), facilitate immediate physical reactions associated with a preparation for violent [[muscular]] action.<ref name=gleitman>{{Cite book|author= [[Henry Gleitman]], Alan J. Fridlund and [[Daniel Reisberg]] |title= Psychology |edition= 6 |year= 2004 |publisher= [[W. W. Norton & Company]] |isbn= 978-0-393-97767-7 }}</ref>

===Function of physiological changes===
The physiological changes that occur during the fight or flight response are activated to give the body increased strength and speed in anticipation of fighting or running. Some of the specific physiological changes and their functions include:<ref name="Physiological Changes - Tripod2">{{cite web |last=Stress Management for Health Course |title=The Fight Flight Response |url=http://stresscourse.tripod.com/id11.html |access-date=19 April 2013}}</ref><ref name="The Science of Stress - Olpin2">{{cite web |last=Olpin |first=Michael |title=The Science of Stress |url=http://faculty.weber.edu/molpin/healthclasses/1110/bookchapters/stressphysiologychapter.htm |url-status=dead |archive-url=https://web.archive.org/web/20171120215838/http://faculty.weber.edu/molpin/healthclasses/1110/bookchapters/stressphysiologychapter.htm |archive-date=2017-11-20 |access-date=2013-04-25 |publisher=Weber State University}}</ref><ref name=":23">{{Cite book |last1=Myers |first1=David G. |title=Psychology |last2=DeWall |first2=C. Nathan |publisher=MacMillan Publishing |year=2021 |edition=13 |pages=422}}</ref>

* Increased [[blood flow]] to the muscles activated by diverting blood flow from other parts of the body to make taking quick action easier.
* Increased blood pressure and heart rate enhance cardiac output in order to supply the body with more energy.
* The [[liver]] secretes increased amounts of [[glucose]] (through adrenaline-induced [[glycogenolysis]])<ref>{{Cite web |title=Glycogenolysis {{!}} Glucose Metabolism, Liver Function & Regulation {{!}} Britannica |url=https://www.britannica.com/science/glycogenolysis |access-date=2025-01-09 |website=www.britannica.com |language=en}}</ref> and fats into the blood to provide the body with a fuel source to meet energy demands.
* The [[respiratory rate]] increases to supply the oxygen necessary to help burn the extra glucose.
* The [[Coagulation|blood clotting]] function of the body speeds up in order to reduce [[bleeding]] and prevent excessive blood loss in the event of an injury sustained during the response.
* Increased [[Muscle tone|muscle tension]] in order to provide the body with extra speed and strength, which can result in trembling or shaking until the tension is released.
* The pupils [[Mydriasis|dilate]] to let in more light, allowing for better vision of the body's surroundings.