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Digestive System - Digestive System The alimentary canal It...

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1 Digestive System - The alimentary canal It is a hollow tube of varying diameter, consisting of the esophagus, stomach, small intestine, and large intestine (comprising mecum, colon, rectum and anal canal). Four layers: (1) the mucosa , (2) the submucosa , (3) the muscularis externa and (4) the adventitia These layers can be strikingly different in appearance in different parts of the alimentary canal. Shear mechanic reflex most diet will trigger you drink (needs water for lubrication) Esophagus reflex and mechanical mobilize food down to the stomach The submucosa lies under mucosa and consists of fibrous connective tissue The muscularis externa is made up of three layers of smooth muscle In the empty state, the stomach is contracted and its mucosa and submucosa are thrown up into distinct folds called rugae ; when distended with food, the rugae are "ironed out" and flat. - Stomach Dilated portion of the digestive system located primarily in the upper left quadrant Stomach rotates during embryonic development so that the lesser curvature (originally the anterior surface) faces superiorly and to the right The greater curvature (originally the posterior surface) faces inferiorly and to the left three layers of muscles longitudinal layer/ circular layer/ oblique layer; Rugae of mucosa allow the stomach to expend allow space increase Store food until those food broken down Parietal cells produce gastric acid and intrinsic factor Near the top of the pits, closest to the contents of the stomach are goblet cells which form the mucus gel layer above the mucosa which help protect the stomach from self-digestion pH value = 2; high [H + ] Breakdown food The gastric emptying is determined by the osmlarity of the fluid in stomach high osm delay the gastric emptying thus the sport drink should be designed to make osm close to ph=7 can accelerate the gastric emptying! Stomach ulcer Bacterial infection (Noble Prize) Stress increase gastric acid secretion break down the stomach mucosa (Monkey study make wrong decision partner gets electrical shock! stress increase ulcer!!!)
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2 - Small intestine Part of the small intestine between the stomach proximally and the large intestine distally Jejunum is approximately 8 feet in length Wall of the jejunum is thicker than the wall of the ileum
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