lec 10 gisystem.pptx

lec 10 gisystem.pptx - GI Hormones Introduction to the...

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Page 1 Introduction to the endocrinology of the GI tract: neurogenic components, endocrine components and regulatory mechanisms. Enteroendocrine cells, hormone families, hormones of the GI tract and their neuroendocrine control. GI hormones: Gastrin / CCK family: gastrin, CCK; Secretin family: secretin, VIP, GIP, GLP; PP family: PPY, peptide YY, NPY; Other GI hormones: neurotensin, galanin, GRP, motilin, TRH, CGRH, SS, enkephalins, endorphins, SP. Neuroendocrine control of food intake Pathologies associated with GI hormones GI Hormones 18 VIP Introduction GI Hormones and “story lines” serosa muscle, circular layer submucosal plexus (synapses) submucosa muscularis mucosae mucosa oral end aboral end GI tract lumen muscle, longuitudinal layer myenteric plexus (synapses)
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Page 2 The GI tract GI Hormones Pathologies Introduction Overview of the GI tract: neurogenic and endocrine components, and regulatory mechanisms S ± E The gastrointestinal tract. A. The stomach and its functional segments. The lining of the body or corpus contains the acid secreting oxyntic mucosa. The antrum and pylorus control access to the initial portion of the intestine, the duodenum. B. The accessory digestive organs, the liver and pancreas. Bile contains excretory products and the sterols and phospholipids that emulsify ingested fats and facilitate their digestion and absorption. C. The intestines. The duodenum is about 30 cm long and leads into the jejunum (about 2.5 meters long), which in turn leads into the ileum (about 3.8 meters long). The large intestine, the colon, is comprised of the ascending, transverse, and descending portions. The GI tract GI Hormones Pathologies Introduction Overview of the GI tract: neurogenic and endocrine components, and regulatory mechanisms S ± E Gastric glands. Hormone secreting cells in the epithelial lining of the stomach and intestinal tract are present in deep invaginations of the mucosal surface scattered among cells of various functions. A. Schematic representation of an oxyntic pit. Note that the acid-producing parietal cells, the enzyme- producing chief cells, and the mucus-producing cells and the differentiating cells that renew the mucosal surface are all “open” to the lumen and come in direct contact with the luminal contents. The ECL (enterochromaffin-like) cells, the somatostatin-secreting D cells, and the ghrelin producing cells are “closed” and have no direct contact with luminal contents. B. Schematic representation of the antral pit. Note that parietal cells are absent, and that the somatostatin producing D cells, the gastrin- producing G cells, and the enterochromaffin cells are “open” and come in contact with the luminal contents. A similar arrangement of cells is seen in the crypts of the mucosae of the small and large intestines.
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Page 3 The GI tract GI Hormones Pathologies Introduction Overview of the GI tract: neurogenic and endocrine components, and regulatory mechanisms S ± E
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lec 10 gisystem.pptx - GI Hormones Introduction to the...

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