PHYS 1525 Gastrointestinal Physiology

PHYS 1525 Gastrointestinal Physiology - moderate inhibition...

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Visceral Physiology December 8, 2008 Gastrointestinal Physiology 1) Nervous control of GI tract motility - Enteric nervous system made up of: Myenteric (Auerbach’s) plexus – outer plexus lying between longitudinal and circular muscle layers – mainly controls GI movement Submucosal (Meissner’s) plexus – inner plexus – mainly controls GI secretions and local blood flow 2) GI hormones (name, source, major function) - Gastrin Secreted by the “G” cells of the antrum of the stomach in response to stimuli associated with eating a meal Major functions – stimulation of gastric acid secretion and stimulation of growth of the gastric mucosa - Cholecystokinin Secreted by the “I” cells in the mucosa of the duodenum and jejunum mainly in response to digestive products of fat, fatty acids, and monoglycerides in the intestinal contents Major function – contraction of the gallbladder and
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Unformatted text preview: moderate inhibition of stomach contraction to allow adequate time for digestion of fats in the upper intestinal tract-Secretin Secreted by the S cells in the mucosa of the duodenum in response to acidic gastric juice emptying into the duodenum from the stomach Major function mild effect on the motility of the GI tract and acts to promote pancreatic secretion of bicarbonate -Gastric inhibitory peptide Secreted by the mucosa of the upper small intestine, mainly in response to fatty acids and amino acids but to a lesser extent in response to carbohydrates Major function mild effect in decreasing motor activity of the stomach and therefore slow the emptying of gastric contents into the duodenum-Motilin Secreted by the upper duodenum during fasting Major function increases gastrointestinal motility...
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