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27 Cards in this Set
- Front
- Back
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GI Physiology 2010 part II
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-Regulates emptying of gastric contents at a rate which chyme can be processed by duodenum
-Prevents regurgitation of duodenal contents back into stomach |
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Where is the chemoreceptor trigger zone for vomiting located?
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-Rostral medulla
-outside blood brain barrier and can be reached by chemicals in the blood |
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explain the nucleus tractus solitarius (solitary nucleus) and its involvement in vomiting?
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Receives input from vagus, labyrinhs and chemoreceptor trigger zone
-coordinates somatic motor response in reponse to vomiting |
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How can motion sickness (semicircular canal stimulation) be prevented?
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-impulses are transmitted to chemoreceptor trigger zone before going to vomiting center. Antihistamines (H1) blockers can prevent motion sickness by acting
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ipecac
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-stimulates vomiting
-stimulates receptor in stomach or duodenum |
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How does morphine and horomones (pregnancy) stimulate vomiting?
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Act at chemoreceptor trigger zone
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retrograde propulsion during emesis is driven entirely by _______
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extrinsic nerves
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Clinical consequences of vomiting?
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-metabolic alkalosis
-dehydration -hypokalemia |
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How long does it take for chyme to go thru small intestine?
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-2 hours
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What things are absorbed through the stomach instead of the small intestine?
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-alcohol, asprin and perhaps a small amount of fat are absorbed through the stomach
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circular folds vs villi vs microvilli in small intestine
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-circular folds: increase surface area by 3-fold, folds of mucosal and submucosal
-villi: increase surface area by 10-fold, contain blood and lacteals -microvilli: 20-fold, contain enzymes, and brush border. |
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T or F basic electrical rhythm (frequecny of slow waves) are dependent on extrinsic innervation?
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FALSE
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Most common type of movement in the small intestine?
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segmentation
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frequency of segmentation and slow waves in the small intestine?
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11 or 12 contractions/min in duodenum and 8 or 9 contractions/min in ileum
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How far do peristalic waves travel in the small intestine?
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less than 5 cm (segmentation is more prominent)
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local reflex in small intestine?
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-propells bolus aborally
-mediated by intramural plexuses |
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intestinointestinal reflex in small intestine?
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-over distention in one segment of the intestine relaxed the rest of the intestine.
-requires extrinsic innervation |
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gastroileal reflex in small intestine?
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-increased secretory and motor activity in the stomach increase motility in terminal part of the ileum and quickens the movement of chyme through the ileoc
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What is responsible for the MMC complex in the small intestine?
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-ENS and the hormone motilin
-extrinsic innervation is not required |
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properties of the MMC in the small intestine?
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-cleans and empties small intestine
-inhibits migration of colonic bacteria into ileum -disrupted by psychological stress (causes over growth of bacteria in ileum) -ends promptly with eating |
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sympathetic innervation of the colon?
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-from mesenteric and hypogastric ganglia
-inhibits motility |
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Hirschsprung's disease
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-result of congenital abnormality in which enteric nervous system does not develop properly, but can also caused by radiation damage during cancer therapy
-colon becomes constricted in the region where the intramural plexus is absent |
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Exocrine secretion
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-gland cells release their secretory products into ducts
-ducts open onto an epithelial surface of the body |
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endocrine secretion
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-a hormone elaborated in an endorcrine cell is released into the blood stream to act at a distant target
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neurocrine secretion
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-hormone synthesized in neuron and relased into the blood stream to act on a distant target
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paracrine secretion
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-hormone relased from a cell diffuses short distance in interstitial fluid to nearby target cell
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secretagogue
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-substance that stimulates secretion from a cell
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