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Esdin LS 2 Lec 10 Digestive

Located proximally lower esophageal sphincter is

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Unformatted text preview: t release saliva 5 4/21/13 unidirectional The Esophagus sphincter: ring of smooth muscles to prevent from going back up •  Muscular tube •  Upper esophageal sphincter is located proximally •  Lower esophageal sphincter is distal •  Peristaltic waves push food down muscle contractions The Esophagus Upper esophageal sphincter Lower esophageal sphincter 6 4/21/13 big The Stomach Esophagus Gastroesophageal sphincter Smooth muscle fundus Rugae the folds, to increase surface area Pyloric sphincter body pylorus Duodenum The Stomach •  Located between the esophagus and the small intestine •  Starts the digestion of proteins •  Functions in gastric mixing and gastric emptying 7 4/21/13 bolus: in mouth, chyme: in stomach Gastric Emptying proximal: beginning of stomach Esophagus stomach is mixing, this is closed Gastroesophageal sphincter Direction of movement of peristaltic contraction Pyloric sphincter Movement of chyme Peristaltic contraction Duodenum slowly releases small pieces of food into the large intestine Gastric Mixing Peristaltic contraction 8 4/21/13 Gastric Mucosa Gastric pit lined with sp. cells small openings Mucosa inner layer Stomach lumen Submucosa outer layer Gastric Mucosa Surface epithelial cells Gastric pit Mucosa cells Chief cells Parietal cells 9 4/21/13 Gastric Mucosa •  Mucosa cells –  Release mucus rich in bicarbonate •  Chief cells important enzyme –  Release pepsinogen inactive form (ogen suffix) •  Parietal cells B-12 intrinsic factor –  Release HCl, and ______ protein important for the consumption of Vitaminblood important for formation of activates the pepsinogen --> pepsin --> now can digest proteins Pepsinogen Activation pepsin digests any proteins it encounters; because of this, we release it in inactive form so that it doesn't digest cellular proteins that are important to the body Pepsin ! HCl Pepsinogen Chief cells " Protein Smaller peptide fragments lumen mucosa Parietal cells 10 4/21/13 Accessory Digestive Organs don't directly interact with the food •  Salivary glands –  Sublingual, submandibul...
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