Stomach fundus

Peripheral Gl, vascular and bronchial smooth muscle, vascular endothelium, platelets Peripheral Smooth muscle of ileum, stomach fundus (rat), uterus, vasculature, endothelium Peripheral None identified Peripheral Post-ganglionic sympathetic neurons, sensory neurons Peripheral Cardiac muscle, post-ganglionic parasympathetic neurons (myenteric plexus), esophageal and vascular smooth muscle... 

Fundus uppermost region of the stomach located above the junction with the esophagus... 

Food is stored in the body of the stomach, which may expand to hold as much as 11 of chyme. As food enters the stomach, it undergoes a reflex relaxation referred to as receptive relaxation. It enhances the ability of the stomach to accommodate an increase in volume with only a small increase in stomach pressure. The fundus does not typically store food because it is located above the esophageal opening into the stomach. Instead, it usually contains a pocket of gas. 

For the most part, the resting pH of the stomach is nearer to 2 than 1 however, during feeding the meal causes a transient rise in pH to 4—5 depending on the volume and nature of the meal consumed. The fundus undergoes receptive relaxation to allow the proximal stomach to accommodate the food mass in the distal stomach, the food is triturated to form chyme, which is ejected into the duodenum in spurts of 2-5 mL. The division of function causes significant inhomogeneity in... 

Nomura and Ogata provided the first evidence that tunicates can produce PGs [17]. Using a rat stomach fundus bioassay, Halocynthia roretzi tissues were shown to possess low levels of PGs. The testes showed higher levels (9 ngg-1 wet tissue) than ovary and muscle tissue. The sea-squirt Styela clava did not show PGs by this method. No structures were determined in this work. Reexamination of the ability of H, roretzi to produce PGs was carried out by Ogata and coworkers [19]. Incubation of selected tissues with 14C-labeled eicosa-8,11,14-trienoic acid and subsequent isolation of PGE and PGF fractions after addition of carrier showed the branchial tissue to have the highest conversion levels. Quantitation was done by LSC. Using a TLC radioscanner, the authors determined that fractions with metabolites similar to PGE and PGF... 

Cox, D. A. and Cohen, M. L. 5-HT2B receptor signaling in the rat stomach fundus dependence on calcium influx, calcium release and protein kinase C. Behav. Brain Res. 73 289-292,1996. 

A second important nonneuronal site of histamine storage and release is the enterochromaffin-like (ECL) cells of the fundus of the stomach. ECL cells release histamine, one of the primary gastric acid secretagogues, to activate the acid-producing parietal cells of the mucosa (see Chapter 62). 

A scheme illustrating the possible mechanisms by which N -methylhistamine produced by H.p. may influence parietal cell function is shown in Figure 3. This scheme clearly shows that N -methylhistamine produced by H.p. could change the regulation of acid secretion in two opposite ways its effect on histamine formation in the fundus could reduce acid secretion, whereas the effect on somatostatin in the antrum could induce hypergastrinemia and thus increase acid secretion One could speculate that the final effect of this bacterium on acid production would depend on its distribution in the stomach. 

Schubert, M.L., Harrington, L., Makhlouf,. G.M., 1993. Histamine H3-receptors are coupled to inhibition of somatostatin secretion in the fundus and antrum of the stomach. Gastroenterology 104 (Suppl), A854. 

Vuyyuru, L., Harrington, L., Arimura, A., Schubert, ML. (1997). Reciprocal inhibitory paracrine pathways link histamine and somatostatin secretion in the fundus of the stomach. Am. J. Physiol. 273, G106-G111. 

Stomach. The stomach is the first digestive organ that a drug encounters in the alimentary canal. The human stomach can be divided anatomically into (1) the cardia, the gastroesophageal sphincter, (2) the fundus, the uppermost part of stomach, (3) the body, a reservoir for food and fluids, and (4) the antrum, the lower part of the stomach. The diameter of the stomach in the fed state is quite variable depending on the area. The antrum diameter does not change much in the fed state, whereas the diameter of the body may increase several-fold. 

Parietal (oxyntic) cells located predominantly in the body and fundus of the stomach secrete hydrochloric acid. The gastric pH is not constant owing to variation in acid secretion and gastric content. The pH in the stomach at different states of feeding and various parts of the small intestine is shown in Table 2.1. The mucus layer restricts the diffusion of hydrogen ions secreted by the intestinal epithelial cells. As a result, the pH of this 700- m-thick microclimate region is on the order 5.8 to... 

Foguet M, Hoyer D, Pardo LA, et al. Cloning and functional characterization of the rat stomach fundus serotonin receptor. EMBO J 1992 11 3481-3487. 

Foguet M, Nguyen H, Le H, Lubbert H. Structure of the mouse 5-HT1C, 5-HT2 and stomach fundus serotonin receptor genes. Neuroreport 1992 3 345-348. 

Kursar JD, Nelson DL, Wainscott DB, Cohen ML, Baez M. Molecular cloning, functional expression, and pharmacological characterization of a novel serotonin receptor (5-hydroxytryptaminc2l ) from rat stomach fundus. Mol Pharmacol 1992 42 549-557. 

Cox DA, Blase DK, Cohen ML. Bradykinin and phorbol ester but not 5-HT2B receptor activation stimulate phospholipase D activity in the rat stomach fundus. Prog Neuropsychopharmacol Biol Psychiatry 1999 23 697-704. 

Q9 The stomach secretes a very acid gastric juice with a pH of 1.5-2. The mucosa is normally protected from acid by a number of mechanisms. Mucus is produced by the large number of mucous cells in the body and fundus. It contains glycoproteins called mucins, and the mucus produced forms a kind of gel which coats the mucosal surface. In addition these cells secrete HCO3-, which is trapped in the mucus and increases the local pH to form a less acidic environment at the surface of the epithelial cells. 

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