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Control of Feeding - Anatomy & Physiology (view source)
Revision as of 08:19, 17 July 2008
, 08:19, 17 July 2008→Phases of Gastric Secretion
*Vagus nerve (CN X)
*Vagus nerve (CN X)
**Parasympathetic fibres
**Synapse in submucosal plexus
*[[Endocrine System - Gut - Anatomy & Physiology|Gastrin]] secreted from endocrine cells in pyloric mucosa
*[[Endocrine System - Gut - Anatomy & Physiology|Gastrin]] secreted from endocrine cells in pyloric mucosa
*Postganglionic fibres activate chief, parietal, mucous and G cells
*Histamine secreted from paracrine action
*Histamine secreted from paracrine action
*Increase stomach motility by release of hydrochloric acid and pepsinogen
*Increase stomach motility by release of hydrochloric acid and pepsinogen
*Short phase
*Overlaps with gastric phase of secretion
*Inhibited by stress, increased by aggression
[[Image:gastric control of secretion diagram.jpg|thumb|right|150px|Gastric control of secretion - Copyright RVC 2008]]
[[Image:gastric control of secretion diagram.jpg|thumb|right|150px|Gastric control of secretion - Copyright RVC 2008]]
===Gastric===
===Gastric===
*Chemical and mechanical receptors in stomach
*Chemical and mechanical receptors in stomach respond to stretch and chemical stimulation
*Increase in pH of gastric contents
*Response to undigested materials, especially proteins
*Histamine and gastrin released
*Histamine and gastrin released
*Negative feedback loop by sympathomimetic somatostatin released by paracrine method to inhibit gastrin secretion (when pH falls below 3)
*Negative feedback loop by sympathomimetic somatostatin released by paracrine method to inhibit gastrin secretion (when pH falls below 3)
*Submucosal and myenteric plexuses activated in vagus reflex arcs
*Postganglionic release of ACh at parietal cells
*Neural response and presence of peptides in chyme stimulate gastrin release
*Parietal and chief cells stimulate via gastrin acting in the bloodstream
*Long response
[[Image:Intestinal control of secretion diagram.jpg|thumb|right|150px|Intestinal control of secretion - Copyright RVC 2008]]
[[Image:Intestinal control of secretion diagram.jpg|thumb|right|150px|Intestinal control of secretion - Copyright RVC 2008]]
===Intestinal===
===Intestinal===
*Chyme in the duodenum inhibits acid secretion and motility
*Chyme in the [[Duodenum - Anatomy & Physiology|duodenum]] inhibits acid secretion and motility by decreasing the stomach distension and increasing the stretch of the [[Duodenum - Anatomy & Physiology|duodenum]] leading to the enterogastric reflex
*A drop in pH below 4.5 causes release of secretin which inhibits parietal and chief cells and stimulate buffer release from the [[Pancreas - Anatomy & Physiology|pancreas]]
*Chyme causes release of secretin, [[Endocrine System - Gut - Anatomy & Physiology|GIP]] and [[Endocrine System - Gut - Anatomy & Physiology|CCK]]
*Chyme causes release of secretin, [[Endocrine System - Gut - Anatomy & Physiology|GIP]] and [[Endocrine System - Gut - Anatomy & Physiology|CCK]] decreasing gastric sectreions and motility
[[Image:Pancreatic control of secretion diagram.jpg|thumb|right|150px|Pancretic control of secretion - Copyright RVC 2008]]
[[Image:Pancreatic control of secretion diagram.jpg|thumb|right|150px|Pancretic control of secretion - Copyright RVC 2008]]
===Pancreatic===
===Pancreatic===