The cough reflex occurs when stimulation of cough receptors in the respiratory tract by dust or other foreign particles produces a cough, which causes rapidly moving air which usually remove the foreign material before it reaches the lungs. This typically clears particles from the bronchi and trachea, the tubes that feed air to lung tissue from the nose and mouth.[1] The larynx (voice box) and carina (at the bottom of the trachea, as it splits into bronchi) are especially sensitive. Cough receptors in the surface cells (epithelium) of the respiratory tract are also sensitive to chemicals. Terminal bronchioles and even the alveoli are sensitive to chemicals such as sulfur dioxide gas or chlorine gas.[1]
The cough receptors or rapidly adapting irritant receptors are located mainly on the posterior wall of the trachea, larynx, and at the carina of trachea, the point where the trachea branches into the main bronchi. The receptors are less abundant in the distal airways and absent beyond the respiratory bronchioles. When triggered, impulses travel via the internal laryngeal nerve, a branch of the superior laryngeal nerve which stems from the vagus nerve (CN X) to the medulla of the brain. This is the afferent neural pathway. Unlike other areas responsible for involuntary actions like swallowing, there is no definitive area that has been identified as the cough center in the brain.
The efferent neural pathway then follows, with relevant signals transmitted back from the cerebral cortex and medulla via the vagus and superior laryngeal nerves to the glottis, external intercostals, diaphragm, and other major inspiratory and expiratory muscles. The mechanism of a cough is as follows:
The abdominal muscles contract to accentuate the action of the relaxing diaphragm; simultaneously, the other expiratory muscles contract. These actions increase the pressure of air within the lungs.
The vocal cords relax and the glottis opens, releasing air at over 100 mph.
The bronchi and non-cartilaginous portions of the trachea collapse to form slits through which the air is forced, which clears out any irritants attached to the respiratory lining.
Stimulation of the auricular branch of the vagus nerve supplying the ear may also elicit a cough. This ear-cough reflex is also known as Arnold's nerve reflex (ANR), linked to the auricular branch of vagus nerve. It is an example of vagal hypersensitivity.[2][3] Weakness of the respiratory muscles, tracheostomy, or vocal cord pathology (including paralysis or anesthesia) may prevent effective clearing of the airways.
Dysfunctionedit
The reflex is impaired in the person whose abdominals and respiratory muscles are weak. This problem can be caused by disease conditions that lead to muscle weakness or paralysis, by prolonged inactivity, or as outcome of surgery involving these muscles.[citation needed] Bed rest interferes with the expansion of the chest and limits the amount of air that can be taken into the lungs in preparation for coughing, making the cough weak and ineffective.[citation needed] This reflex may also be impaired by damage to the internal branch of the superior laryngeal nerve which relays the afferent branch of the reflex arc.[citation needed] This nerve is most commonly damaged by swallowing a foreign object, such as a chicken bone, resulting in it being lodged in the piriform recess (in the laryngopharynx) or by surgical removal of said object.
Testingedit
The cough reflex can be tested by inhaling air with nebulized 200 μmol/L capsaicin.[4]
^ abHall, John (2011). Guyton and Hall Textbook of Medical Physiology with Student Consult Online Access (12th ed.). Philadelphia: Elsevier Saunders. p. 473. ISBN978-1-4160-4574-8.
^Zhang, Mengru; Morice, Alyn H. (2023-08-29). "Unravelling vagal hypersensitivity in chronic cough: A distinct disease". The Journal of Physiology. doi:10.1113/JP284641. ISSN 0022-3751. PMID 37642341.
^Dicpinigaitis, Peter V.; Kantar, Ahmad; Enilari, Oladunni; Paravati, Francesco (2018). "Prevalence of Arnold Nerve Reflex in Adults and Children With Chronic Cough". Chest. 153 (3): 675–679. doi:10.1016/j.chest.2017.11.019. ISSN 1931-3543. PMID 29197546.
^Hegland, K. W.; Bolser, D. C.; Davenport, P. W. (2012). "Volitional control of reflex cough". Journal of Applied Physiology. 113 (1): 39–46. doi:10.1152/japplphysiol.01299.2011. PMC3774289. PMID 22492938.
Ganong WF, "Chapter 36. Regulation of Respiration" (Chapter). Ganong WF: Review of Medical Physiology, 22nd Edition:
January 01, 1970
cough, reflex, cough, reflex, occurs, when, stimulation, cough, receptors, respiratory, tract, dust, other, foreign, particles, produces, cough, which, causes, rapidly, moving, which, usually, remove, foreign, material, before, reaches, lungs, this, typically,. The cough reflex occurs when stimulation of cough receptors in the respiratory tract by dust or other foreign particles produces a cough which causes rapidly moving air which usually remove the foreign material before it reaches the lungs This typically clears particles from the bronchi and trachea the tubes that feed air to lung tissue from the nose and mouth 1 The larynx voice box and carina at the bottom of the trachea as it splits into bronchi are especially sensitive Cough receptors in the surface cells epithelium of the respiratory tract are also sensitive to chemicals Terminal bronchioles and even the alveoli are sensitive to chemicals such as sulfur dioxide gas or chlorine gas 1 Contents 1 Physiology of cough 2 Dysfunction 3 Testing 4 See also 5 References 6 Further readingPhysiology of cough editThe cough receptors or rapidly adapting irritant receptors are located mainly on the posterior wall of the trachea larynx and at the carina of trachea the point where the trachea branches into the main bronchi The receptors are less abundant in the distal airways and absent beyond the respiratory bronchioles When triggered impulses travel via the internal laryngeal nerve a branch of the superior laryngeal nerve which stems from the vagus nerve CN X to the medulla of the brain This is the afferent neural pathway Unlike other areas responsible for involuntary actions like swallowing there is no definitive area that has been identified as the cough center in the brain The efferent neural pathway then follows with relevant signals transmitted back from the cerebral cortex and medulla via the vagus and superior laryngeal nerves to the glottis external intercostals diaphragm and other major inspiratory and expiratory muscles The mechanism of a cough is as follows Diaphragm innervated by phrenic nerve and external intercostal muscles innervated by segmental intercostal nerves contract creating a negative pressure around the lung Air rushes into the lungs in order to equalise the pressure The glottis closes muscles innervated by recurrent laryngeal nerve and the vocal cords contract to shut the larynx The abdominal muscles contract to accentuate the action of the relaxing diaphragm simultaneously the other expiratory muscles contract These actions increase the pressure of air within the lungs The vocal cords relax and the glottis opens releasing air at over 100 mph The bronchi and non cartilaginous portions of the trachea collapse to form slits through which the air is forced which clears out any irritants attached to the respiratory lining Stimulation of the auricular branch of the vagus nerve supplying the ear may also elicit a cough This ear cough reflex is also known as Arnold s nerve reflex ANR linked to the auricular branch of vagus nerve It is an example of vagal hypersensitivity 2 3 Weakness of the respiratory muscles tracheostomy or vocal cord pathology including paralysis or anesthesia may prevent effective clearing of the airways Dysfunction editThe reflex is impaired in the person whose abdominals and respiratory muscles are weak This problem can be caused by disease conditions that lead to muscle weakness or paralysis by prolonged inactivity or as outcome of surgery involving these muscles citation needed Bed rest interferes with the expansion of the chest and limits the amount of air that can be taken into the lungs in preparation for coughing making the cough weak and ineffective citation needed This reflex may also be impaired by damage to the internal branch of the superior laryngeal nerve which relays the afferent branch of the reflex arc citation needed This nerve is most commonly damaged by swallowing a foreign object such as a chicken bone resulting in it being lodged in the piriform recess in the laryngopharynx or by surgical removal of said object Testing editThe cough reflex can be tested by inhaling air with nebulized 200 mmol L capsaicin 4 See also editCoughReferences edit a b Hall John 2011 Guyton and Hall Textbook of Medical Physiology with Student Consult Online Access 12th ed Philadelphia Elsevier Saunders p 473 ISBN 978 1 4160 4574 8 Zhang Mengru Morice Alyn H 2023 08 29 Unravelling vagal hypersensitivity in chronic cough A distinct disease The Journal of Physiology doi 10 1113 JP284641 ISSN 0022 3751 PMID 37642341 Dicpinigaitis Peter V Kantar Ahmad Enilari Oladunni Paravati Francesco 2018 Prevalence of Arnold Nerve Reflex in Adults and Children With Chronic Cough Chest 153 3 675 679 doi 10 1016 j chest 2017 11 019 ISSN 1931 3543 PMID 29197546 Hegland K W Bolser D C Davenport P W 2012 Volitional control of reflex cough Journal of Applied Physiology 113 1 39 46 doi 10 1152 japplphysiol 01299 2011 PMC 3774289 PMID 22492938 Further reading editCough Reflex http www healthhype com cough reflex physiology process ear cough reflexes html Ganong WF Chapter 36 Regulation of Respiration Chapter Ganong WF Review of Medical Physiology 22nd Edition https web archive org web 20071221162754 http www accessmedicine com content aspx aID 706628 Retrieved from https en wikipedia org w index php title Cough reflex amp oldid 1215835099, wikipedia, wiki, book, books, library,
