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17 Cards in this Set
- Front
- Back
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ENTEROCYTE villus vs. crypt: nutrient transport
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High in villus, low in crypt
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ENTEROCYTE villus vs. crypt: Net water transport
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Villus: absorption, Crypt: secretion
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ENTEROCYTE villus vs. crypt: Permeability
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Villlus: low, Crypt: high
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Which part of the intestine absorbs the most water? Which part most EFFICIENTLY absorbs water?
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Jejunum absorbs the most, but colon is the most EFFICIENT
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Osmolarity of lumen in comparison to PLASMA
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Isosmotic
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Movement of water from the lumen is active or passive?
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Passive
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Which solute/ion most influences movement of water?
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Sodium
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2 methods of water moving through lumen
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Transcellular or paracellular (through tight junctions between cells)
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Which ions does water follow in its absorption in the intestine
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SODIUM and chloride
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Potassium: absorption active or passive?
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PASSIVE -- follows water
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Sodium and Chloride: absorption active or passive?
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ACTIVE
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MOST Inflammatory mediators in GIT cause absorption or secretion?
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Secretion (why IBD causes diarrhea)
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Secretory vs. osmotic diarrhea
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Secretory -- due to infection, enterotoxin, Osmotic -- due to substance in the lumen drawing water out
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How does decreased motility cause diarrhea?
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Bowel not moving -- bacteria moves up into small intestine. Causes decreased electrolyte absorption AND secrete osmotically active substances into lumen (draws out water)
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2 driving forces of SECRETORY diarrhea
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Secretion of chloride or bicarbionate, blocked absorption of sodium
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Mechanism of Toxin A in cholera
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Causes secretion of chloride ions and inhibits absorption of non-nutrient sodium and chloride CONSTITUTIVELY
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Principle behind oral rehydration therapy for cholera
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Cholera toxin ONLY blocks the non-nutrient transport of sodium/chloride. By administering salt with GLUCOSE you increase the nutrient transport of sodium and water follows.
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