Vagovagal reflex refers to gastrointestinal tract reflex circuits where afferent and efferent fibers of the vagus nerve[1] coordinate responses to gut stimuli via the dorsal vagal complex in the brain. The vagovagal reflex controls contraction of the gastrointestinal muscle layers in response to distension of the tract by food. This reflex also allows for the accommodation of large amounts of food in the gastrointestinal tracts.
Vagovagal reflex
Control of stomach acid secretions. (ECL-cell at top center.)
The vagus nerve, composed of both sensory afferents and parasympathetic efferents, carries signals from stretch receptors, osmoreceptors, and chemoreceptors to dorsal vagal complex where the signal may be further transmitted to autonomic centers in the medulla. Efferent fibers of the vagus then carry signals to the gastrointestinal tract up to two-thirds of the transverse colon (coinciding with the second GI watershed point).
Function
The vagovagal reflex is active during the receptive relaxation of the stomach in response to swallowing of food (prior to it reaching the stomach). When food enters the stomach a "vagovagal" reflex goes from the stomach to the brain, and then back again to the stomach causing active relaxation of the smooth muscle in the stomach wall. If vagal innervation is interrupted then intra-gastric pressure increases. This is a potential cause of vomiting due to the inability of the proximal stomach smooth muscle to undergo receptive relaxation.
The vagal afferents are activated during the gastric phase of digestion when the corpus and fundus of the stomach are distended secondary to the entry of a food bolus. The stimulation of the mechanical receptors located in the gastric mucosa stimulates the vagus afferents. The completion of the reflex circuit by vagus efferents leads to the stimulation of postganglionic muscarinic nerves. These nerves release acetylcholine to stimulate two end effects. One, the parietal cells in the body of the stomach are stimulated to release H+. Two, the ECL cells of the lamina propria of the body of the stomach are stimulated to release histamine. Vagal stimulation of the peptidergic neurons, occurring simultaneously, leads to the release of gastrin-releasing-peptide. Finally, the Delta cells are inhibited to reduce the inhibition of gastrin release.
^Herman MA, Cruz MT, Sahibzada N, Verbalis J, Gillis RA (January 2009). "GABA signaling in the nucleus tractus solitarius sets the level of activity in dorsal motor nucleus of the vagus cholinergic neurons in the vagovagal circuit". Am. J. Physiol. Gastrointest. Liver Physiol. 296 (1): G101–11. doi:10.1152/ajpgi.90504.2008. PMC2636929. PMID 19008339.
Binder, Henry. "Organization of the Gastrointestinal System."Medical Physiology. 1st ed. 2002. Print.
January 06, 2023
vagovagal, reflex, confused, with, vasovagal, response, refers, gastrointestinal, tract, reflex, circuits, where, afferent, efferent, fibers, vagus, nerve, coordinate, responses, stimuli, dorsal, vagal, complex, brain, vagovagal, reflex, controls, contraction,. Not to be confused with Vasovagal response Vagovagal reflex refers to gastrointestinal tract reflex circuits where afferent and efferent fibers of the vagus nerve 1 coordinate responses to gut stimuli via the dorsal vagal complex in the brain The vagovagal reflex controls contraction of the gastrointestinal muscle layers in response to distension of the tract by food This reflex also allows for the accommodation of large amounts of food in the gastrointestinal tracts Vagovagal reflexControl of stomach acid secretions ECL cell at top center IdentifiersTHH3 04 02 0 00030Anatomical terminology edit on Wikidata The vagus nerve composed of both sensory afferents and parasympathetic efferents carries signals from stretch receptors osmoreceptors and chemoreceptors to dorsal vagal complex where the signal may be further transmitted to autonomic centers in the medulla Efferent fibers of the vagus then carry signals to the gastrointestinal tract up to two thirds of the transverse colon coinciding with the second GI watershed point Function EditThe vagovagal reflex is active during the receptive relaxation of the stomach in response to swallowing of food prior to it reaching the stomach When food enters the stomach a vagovagal reflex goes from the stomach to the brain and then back again to the stomach causing active relaxation of the smooth muscle in the stomach wall If vagal innervation is interrupted then intra gastric pressure increases This is a potential cause of vomiting due to the inability of the proximal stomach smooth muscle to undergo receptive relaxation The vagal afferents are activated during the gastric phase of digestion when the corpus and fundus of the stomach are distended secondary to the entry of a food bolus The stimulation of the mechanical receptors located in the gastric mucosa stimulates the vagus afferents The completion of the reflex circuit by vagus efferents leads to the stimulation of postganglionic muscarinic nerves These nerves release acetylcholine to stimulate two end effects One the parietal cells in the body of the stomach are stimulated to release H Two the ECL cells of the lamina propria of the body of the stomach are stimulated to release histamine Vagal stimulation of the peptidergic neurons occurring simultaneously leads to the release of gastrin releasing peptide Finally the Delta cells are inhibited to reduce the inhibition of gastrin release See also EditVasovagal episodeVagus influence on gastric secretions 2 References Edit Herman MA Cruz MT Sahibzada N Verbalis J Gillis RA January 2009 GABA signaling in the nucleus tractus solitarius sets the level of activity in dorsal motor nucleus of the vagus cholinergic neurons in the vagovagal circuit Am J Physiol Gastrointest Liver Physiol 296 1 G101 11 doi 10 1152 ajpgi 90504 2008 PMC 2636929 PMID 19008339 Enterochromaffin like Cells at the US National Library of Medicine Medical Subject Headings MeSH Binder Henry Organization of the Gastrointestinal System Medical Physiology 1st ed 2002 Print Retrieved from https en wikipedia org w index php title Vagovagal reflex amp oldid 1089415031, wikipedia, wiki, book, books, library,
