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32 Cards in this Set
- Front
- Back
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LES & cardia |
secrete mucus & HCO3-; prevent reflux, allow entry of food, regulate belching |
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fundus & body |
secrete H+, HCO3-, intrinsic factor, mucus, pepsinogens, lipase; act as reservoir, tonic force during emptying |
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antrum & pylorus |
secrete mucus & HCO3-; mixing, grinding, sieving, regulate emptying |
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parietal cell |
secrete HCl, intrinsic factor |
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chief cells |
secrete pepsinogen (pepsin digests protein) & gastric lipase |
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enterochromaffin-like cells |
secrete histamine (stimulate acid secretion) |
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enteroendocrine cells |
secrete gastrin (stimulate acid & pepsinogen secretion), somatostatin (inhibit gastrin & HCl secretion) |
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cephalic phase in stomach |
DVC -> PSNS -> ENS -> ACh incr. pepsinogen & HCl secretion, GRP incr. gastrin secretion |
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how is pepsinogen activated? |
HCl |
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gastric phase in stomach |
stomach distended -> short & long neural reflexes -> ENS -> incr. HCl, pepsinogen, gastrin |
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HCl secretion stimulation |
ACh, gastrin, and histamine |
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<pH in 3.5 in antrum |
increase in somatostatin -> decr. gastrin secretion -> decr. HCl & pepsinogen secretion |
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small intestine stimulated by |
luminal distention, H+ ions, hypertonic sol'n, products of digestion |
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ionic components of gastric juice |
very high H+, high Cl-, low K+ and Na+ |
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non-parietal vs/ pure parietal secretions |
non = mostly NaCl; pure = mostly HCl |
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resting state secretions |
mainly non-parietal cells (low HCl, high Na) |
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meal state secretions |
mainly parietal secretions (high HCl, low Na) |
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parietal cell secretion process |
CO2 diffuses into cell --CA --> H2CO3 -> H+ + HCO3- -> H+ actively transported into gastric duct; HCO3- countertransported w/ Cl- -> Cl- diffuse into duct |
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parietal cell changes during secretion |
increase in intracellular canaliculi (tubulovesicle fusion); mitochondria supply ATP for active transport of H+ |
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gastric proton pump |
in apical membrane of parietal cells; target for antisecretory drugs (prilosec) |
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metabolic abnormalities a/w prolonged vomiting |
alkalosis, hypokalemia, hypochloremia, dehydration |
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mucus secretion stimulation |
ACh, physical stimulation |
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mucus purpose |
contains bicarb (neutralize H+), impedes HCl and pepsin movement to mucosal cels |
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motor responses during gastric phase |
1) receptive relaxation 2) mixing & grinding 3) emptying |
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control of receptive relaxation |
vagus nerve activity relaxes musculature in proximal stomach (incr. in volume w/o incr. in intraluminal pressure) |
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peristalsis in stomach |
wave occurs ~ every 20s due to pacemaker cells in longitudinal sm (basal electrical rhythm) |
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control of gastric emptying |
neural and hormonal mechanisms -> affect intragastric pressure, freq./strength of antral peristalsis, pyloric resistance, intraduodenal pressure/resistance |
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enterogastrones |
hormones that inhibit gastric functions; CCK, secretin, PYY, GLP-1 |
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particle size & gastric emptying |
>10mm particles require grinding to smaller particles (takes longer to empty) |
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larger volume in stomach... |
more rapid initial emptying |
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osmolality & gastric emptying |
most rapid w/ isosmotic non-caloric foods |
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pH & gastric emptying |
acidic contents = slower emptying |
