Glomus cell

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A glomus cell (type I) is a peripheral chemoreceptor, mainly located in the carotid bodies and aortic bodies, that helps the body regulate breathing. When there is a decrease in the blood's pH, a decrease in oxygen (pO2), or an increase in carbon dioxide (pCO2), the carotid bodies and the aortic bodies signal the medulla oblongata (specifically the dorsal inspiratory center in the medulla oblongata) to increase the volume and rate of breathing.[1] The glomus cells have a high metabolic rate and good blood perfusion and thus are sensitive to changes in arterial blood gas tension. Glomus cells are very similar structurally to neurons, and they are indeed derived from the neural crest, while type II glomus cells are sustentacular cells having a similar function to neuroglia.[2][3][4]

Autonomic ganglia innervate the glomus cells, and some presynaptic sympathetic ganglia synapse with glomus cells.[5] The nerve fibers pick up the signals sent by glomus cells and transmit them to the central nervous system for treatment.[6] The signalling within the chemoreceptors is thought to be mediated by the release of neurotransmitters by the glomus cells, including dopamine, noradrenaline, acetylcholine, substance P, vasoactive intestinal peptide and enkephalins.[7] Vasopressin has been found to inhibit the response of glomus cells to hypoxia, presumably because the usual response to hypoxia is vasodilatation, which in case of hypovolemia should be avoided.[8] Furthermore, glomus cells are highly responsive to angiotensin II through AT1 receptors, providing information about the body's fluid and electrolyte status.[9]

Clusters of glomus cells, of which the carotid bodies and aortic bodies are the most important, are called non-chromaffin or parasympathetic paraganglia. They are also present along the vagus nerve, in the inner ears, in the lungs, and at other sites. Neoplasms of glomus cells are known as paraganglioma, among other names, they are generally non-malignant.[10]

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  1. ^ Lahiri S, Semenza G, Prabhakar NR, eds. (2003). Oxygen sensing : responses and adaptation to Hypoxia. New York: Dekker. pp. 200, 232. ISBN 0824709608. 
  2. ^ Pearse AG, Polak JM, Rost FW, Fontaine J, Le Lièvre C, Le Douarin N (1973). "Demonstration of the neural crest origin of type I (APUD) cells in the avian carotid body, using a cytochemical marker system". Histochemie. 34 (3): 191–203. doi:10.1007/bf00303435. PMID 4693636. 
  3. ^ Lawson, W (January 1980). "The neuroendocrine nature of the glomus cells: an experimental, ultrastructural, and histochemical tissue culture study". The Laryngoscope. 90 (1): 120–44. doi:10.1288/00005537-198001000-00014. PMID 6243386. 
  4. ^ Eyzaguirre, C; Fidone, SJ (November 1980). "Transduction mechanisms in carotid body: glomus cells, putative neurotransmitters, and nerve endings". The American Journal of Physiology. 239 (5): C135–52. doi:10.1152/ajpcell.1980.239.5.C135. PMID 6108075. 
  5. ^ Singh, Inderbir. Textbook of human histology : (with colour atlas & practical guide) (6a ed.). New Delhi: Jaypee Brothers Medical Publishers. p. 332. ISBN 9380704348. 
  6. ^ Eyzaguirre, C.; Abudara, Verónica (31 March 1999). "Carotid body glomus cells: chemical secretion and transmission (modulation?) across cell-nerve ending junctions". Respiration Physiology. 115 (2): 135–149. doi:10.1016/S0034-5687(99)00020-1. PMID 10385028. 
  7. ^ Pardal, R.; Ludewig, U.; Garcia-Hirschfeld, J.; Lopez-Barneo, J. (11 February 2000). "Secretory responses of intact glomus cells in thin slices of rat carotid body to hypoxia and tetraethylammonium". Proceedings of the National Academy of Sciences. 97 (5): 2361–2366. doi:10.1073/pnas.030522297. PMC 15806Freely accessible. PMID 10681419. 
  8. ^ Wang, ZZ; He, L; Stensaas, LJ; Dinger, BG; Fidone, SJ (February 1991). "Localization and in vitro actions of atrial natriuretic peptide in the cat carotid body". Journal of Applied Physiology. 70 (2): 942–6. PMID 1827111. 
  9. ^ Allen, A. M. (1 August 1998). "Angiotensin AT1 receptor-mediated excitation of rat carotid body chemoreceptor afferent activity". The Journal of Physiology. 510 (3): 773–781. doi:10.1111/j.1469-7793.1998.773bj.x. PMC 2231066Freely accessible. 
  10. ^ Anne Marie McNicol (2010). "Chapter 12: Adrenal medulla and paraganglia". Endocrine Pathology: Differential Diagnosis and Molecular Advance (Springer ed.). p. 281. 

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