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34 Cards in this Set
- Front
- Back
Muscles of chewing are innervated by ..
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motor branch fo CN V
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How does our jaw drop while chewing?
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reflex inhibition of muscle of mastication
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Why is chewing important?
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create more surface area on the food to the enzymes can degrade it; also so we dont choke
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3 stages of swallowing
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voluntary, pharyngeal, esophageal
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Voluntary stage of swallowing
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push food to the back of the mouth
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Pharyngeal stage of swallowing
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soft palate closes passage to nose. pharynx comes closer together. vocal cords tighten/epiglottis closes. upper esophageal sphincter relaxes. pharyngeal muscles swallow
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Pharyngeal stage of swallowing involves what nerves?
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sensory: trigeminal, glossopharyngeal. motor: glossopharyngeal and vagus, also CN 12
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What happens during the esophageal stage of swallowing?
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peristalsis
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What is primary peristalsis?
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continued peristalsis when food enters after pharyngeal stage of swallowing
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What is secondary peristalsis?
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if primary peristalsis doesn't get the food into the stomach, intrinsic nervous innervation starts new peristalsis to move it more
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What type of muscle is in the esophagus?
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upper 1/3 = skeletal (CN 9 and 10). lower 2/3 = smooth (CN10)
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What happens if the vagus nerve to esophagus is cut?
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myenteric plexus will take over after a few days
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What is achalasia?
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lower esophageal sphincter does not open as food approaches
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In obese patients with high intra-abdominal pressure, why do they not always get gastric reflux?
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there is an additional valve-like closure at the end of the esophagus that provide more closure when there is extra pressure in the abdominal cavity. otherwise we would get GERD every time we coughed
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Stomach peristalsis begins in what part?
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starts in body and moves to antrum and gets stronger
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How does retropulsion occur in the stomach?
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persistalsis towards pyloric muscle, but pyloric muscle closes and food goes back up. important for mixing purposes
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What happens when the stomach is empty for more than several hours?
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hunger contractions
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What is the pyloric pump?
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strong antral contractions to move chyme into the duodenum
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To enter the duodenum, the food moves through the ...
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pyloric sphincter
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2 Gastric factors that promote emptying
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distension (food volume) + gastrin secretion (increases pyloric pump)
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5 factors (non-hormonal) in the duodenum that inhibit gastric emptying
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duodenum distension, irritation, chyme acidity, chyme osmolality, already digested chyme
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Hormonal factors from the duodenum that inhibit gastric emptying
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CCK, Secretin, GIP
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Segment contractions in the small intestine have what function?
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mixing/chopping chyme
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Frequency of segmentation in the small intestine is controlled by ...
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slow wave frequency
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Hormonal factors that INCREASE peristalsis in the small intestine
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CCK, Gastrin, insulin, motilin, serotonin
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Hormonal factors that DECREASE peristalsis in the small intestine
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secretin, glucagon
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What is the peristaltic rush?
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during intestinal irritation or diarrhea to quickly move large amounts of chyme down the Gi tract
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What are haustrations?
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out-pouchings of the unstimulated areas of the intestines while other parts are contracting
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Why would a patient with an inflamed appendix not have regular bowel movements?
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if the cecum (where the appendix is attached) is irritated, it prevents ileum peristalsis and closes the ileo-cecal sphincter
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Function of haustrations in the colon
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mixing
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What are mass movements in the colon?
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propulsive movements
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What causes mass movements in the colon?
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stomach/duodenum distension, irritation, extrinsic autonomics
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External anal sphincter innervation
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pudendal nerve (skeletal muscle, voluntary)
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Why does peritonitis cause decreased intestinal motility?
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peritonitis inhibits excitatory enteric nerves
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