Autonomic nervous system

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Autonomic Nervous System

The autonomic nervous system (ANS) is the branch of the peripheral nervous system that allows for communication between the internal organs and the brain, and is responsible for regulating many involuntary processes in the body. The ANS is constantly active, responding to information from an individual’s environment and his or her body to regulate functions such as heart rate, breathing, and digestion.[1][2][3][4]

Function[edit | edit source]

The ANS is split into two main divisions: the sympathetic nervous system (SNS) and parasympathetic nervous system (PNS). The PNS and SNS serve the same organs, but one system will activate a bodily function while the other will inhibit it.[3] This opposition is operated by two main chemical messengers: norepinephrine, which activates (excitatory) and acetylcholine, which inhibits (inhibitory).[1] The two divisions complement each other to regulate the body’s responses.[3] Functions regulated by the ANS include:

Sympathetic nervous system[edit | edit source]

The sympathetic nervous system (SNS) regulates what is referred to as the “fight-or-flight” response, which prepares the body against a perceived stress or threat. Stimulation of the SNS activates an internal alarm response. This causes an increase in:

During perceived stress, the SNS is activated while the PNS is less predominant. This redirects the body’s resources toward processes that are important in an emergency situation, resulting in a decrease in bodily functions controlled by the PNS, which are less important in an emergency situation.[1]

Parasympathetic nervous system[edit | edit source]

The parasympathetic nervous system (PNS) is dominant in conditions referred to as “rest and digest”. It controls body processes during ordinary situations. This division of the ANS helps return the body to resting state after confronting a stressor, helping to conserve energy.[1]

Functions of the PNS include:

Autonomic disorder and dysfunction[edit | edit source]

Symptoms of autonomic dysfunction include:

  • Orthostatic intolerance: dizziness or light-headedness when a person stands up due to a significant decrease in blood pressure, attributed to cardiovascular deconditioning and/or postural idiopathic autonomic neuropathy
  • Alterations in sweating, resulting in heat intolerance
  • Exercise intolerance: inability to regulate heart rate during exercise
  • Gastroparesis: feeling prematurely full due to slow emptying of stomach
  • Constipation or loss of bowel control
  • Hyper or hypoactive bladder
  • Vision problems: inability of pupils to react to light quickly, blurry vision
  • Sexual response problems (men and women)[2][5]

Myalgic encephalomyelitis and the ANS[edit | edit source]

Altered ANS functioning has been seen in many myalgic encephalomyelitis (ME) patients, as they experience various altered autonomic responses. Symptoms of autonomic dysfunction in ME include:

The vagus nerve hypothesis[edit | edit source]

The vagus nerve hypothesis suggests that infection and inflammation of the vagus nerve, a prominent nerve within the ANS, would disrupt normal autonomic function. The vagus nerve communicates information between numerous internal organs and the brain. Infection of the vagus nerve could signal an exaggerated sickness response and perpetuate further dysfunction.[15]

See also[edit | edit source]

Learn more[edit | edit source]

References[edit | edit source]

  1. McCorry, Laurie Kelly (Aug 15, 2007). "Physiology of the Autonomic Nervous System". American Journal of Pharmaceutical Education. 71 (4). ISSN 0002-9459. PMID 17786266. 
  2. "Overview of the Autonomic Nervous System - Brain, Spinal Cord, and Nerve Disorders - Merck Manuals Consumer Version". Merck Manuals Consumer Version. Retrieved Aug 31, 2018. 
  3. "How the Autonomic Nervous System Regulates Body Functions". Verywell Mind. Retrieved Aug 31, 2018. 
  4. pmhdev. "Autonomic Nervous System - National Library of Medicine". PubMed Health. Retrieved Aug 31, 2018. 
  5. 5.05.1 "Neurology | Autonomic Nervous System". YouTube. Nov 11, 2017 – via Ninja Nerd Science. 
  6. Frith, J.; Zalewski, P.; Klawe, J. J.; Pairman, J.; Bitner, A.; Tafil-Klawe, M.; Newton, J. L. (Sep 2012). "Impaired blood pressure variability in chronic fatigue syndrome--a potential biomarker". QJM: monthly journal of the Association of Physicians. 105 (9): 831–838. doi:10.1093/qjmed/hcs085. ISSN 1460-2393. PMID 22670061. 
  7. Van Cauwenbergh, Deborah; Nijs, Jo; Kos, Daphne; Van Weijnen, Laura; Struyf, Filip; Meeus, Mira (Apr 17, 2014). "Malfunctioning of the autonomic nervous system in patients with chronic fatigue syndrome: a systematic literature review". European Journal of Clinical Investigation. 44 (5): 516–526. doi:10.1111/eci.12256. ISSN 0014-2972. 
  8. Rowe, Peter C.; Lucas, Katherine E. (Mar 2007). "Orthostatic Intolerance in Chronic Fatigue Syndrome". The American Journal of Medicine. 120 (3): e13. doi:10.1016/j.amjmed.2006.02.033. ISSN 0002-9343. 
  9. "Heart rate variability in patients with fibromyalgia and patients with chronic fatigue syndrome: A systematic review". Seminars in Arthritis and Rheumatism. 43 (2): 279–287. Oct 1, 2013. doi:10.1016/j.semarthrit.2013.03.004. ISSN 0049-0172. 
  10. 10.010.1 Jones, David E. J.; Hollingsworth, Kieren G.; Jakovljevic, Djordje G.; Fattakhova, Gulnar; Pairman, Jessie; Blamire, Andrew M.; Trenell, Michael I.; Newton, Julia L. (Jul 12, 2011). "Loss of capacity to recover from acidosis on repeat exercise in chronic fatigue syndrome: a case-control study". European Journal of Clinical Investigation. 42 (2): 186–194. doi:10.1111/j.1365-2362.2011.02567.x. ISSN 0014-2972. 
  11. Burnet, Richard B; Chatterton, Barry E (Dec 2004). "Gastric emptying is slow in chronic fatigue syndrome". BMC Gastroenterology. 4 (1). doi:10.1186/1471-230x-4-32. ISSN 1471-230X. 
  12. Maes, Michael; Mihaylova, Ivana; Leunis, Jean-Claude (Apr 2007). "Increased serum IgA and IgM against LPS of enterobacteria in chronic fatigue syndrome (CFS): indication for the involvement of gram-negative enterobacteria in the etiology of CFS and for the presence of an increased gut-intestinal permeability". Journal of Affective Disorders. 99 (1-3): 237–240. doi:10.1016/j.jad.2006.08.021. ISSN 0165-0327. PMID 17007934. 
  13. "Tufts Libraries EZproxy Login". Retrieved Aug 31, 2018. 
  14. "Autonomic correlations with MRI are abnormal in the brainstem vasomotor centre in Chronic Fatigue Syndrome". NeuroImage: Clinical. 11: 530–537. Jan 1, 2016. doi:10.1016/j.nicl.2016.03.017. ISSN 2213-1582. 
  15. VanElzakker, Michael B. (Sep 2013). "Chronic fatigue syndrome from vagus nerve infection: a psychoneuroimmunological hypothesis". Medical Hypotheses. 81 (3): 414–423. doi:10.1016/j.mehy.2013.05.034. ISSN 1532-2777. PMID 23790471. 

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From MEpedia, a crowd-sourced encyclopedia of ME and CFS science and history.