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29 Cards in this Set
- Front
- Back
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Where are bile salts synthesized?
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In the liver from CHOLESTEROL
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What are the properties of bile salts?
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1) Combine with fat-soluble substances to form water soluble complexes (facilitate digestion, transport and absorption of fat)
2) Reduce surface tension and stabilize emulsions 3) Assist in the transport and absorption of fat and fat-soluble vitamins (A,D,E,K) |
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What happens to bile salts after a certain concentration?
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Bile salts come together to form molecular aggregates Micelles
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What are micelles?
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Have a water soluble shell and a core that is lipid soluble
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Where are bile acids on the micelle?
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On the hydrophilic (water soluble) side
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What is the size of the bile salt pool?
How much bile is synthesized daily? How much bile is released daily into intestine? |
Pool: 3.5g
Daily synthesis: 0.5g Daily release: 15-20 g |
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Why don't these numbers add up?
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Most of the bil is reabsorbed into portal blood and returned to the liver
.: the entire bile salt pool is recirculated |
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Where are most of the bile salts reabsorbed?
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Distal ileum (90% of bile salts reabsorbed here, returned to the liver and recirculated)
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What happens to the remaining 10%?
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Escapes into the colon.
Bacteria modify it some of it will still be reabsorbed |
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What is the enterohepatic ciculation?
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Liver --> SI --> duodenum--> reabsorption in portal blood
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What are the fcts of bile salt?
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1) Intraportal: regulate volume of bile secreted by liver.
Regulate synthesis of new bile salts 2) Intrahepatic: keep choesterol in solution 3) Intraintestinal: Emulsify and transport fats 4) Intracolonic: keeps stool from being too hard |
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How do bile salts regulate hepatic bile flow?
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The more bile salts are returned to the liver via portal blood, the larger the **volume** of bile secreted
Positive fdbk: inc amt of bile, inc amount of BS returned |
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What happens to this volume if the ileum is removed?
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Smaller amount of bile salts will be secreted
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How do bile salts in the intraportal regios regulate the synthesis of NEW bile salts?
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The more bile salts are returned, the smaller amount of new bile salts are synthesized
->negative fdbk: more bile salts returned, the less need to be synthesized |
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What happens if the distal ileum is removed?
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Must synthesize new bile salts
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What is the intrahepatic fct of bile salts?
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Keep cholesterol in solution (since its insoluble in water)
->solubility of cholesterol is increased by 2x10^6 in bile |
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What happens if cholesterol is ppt out of solution?
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Can give rise to gallstones
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What are the intraintestinal fcts of bile salts?
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1) Act as detergents and help form stable emulsions
2) Assist in the transport from lumen intointestinal cell of fat and fat-soluble vitamin A,D,E, K |
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What are the intraclonic function of bile salts?
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Inhibit Na+ transport and H2O absorption (small amts of BS in colon keep feces from being too hard)
**Excess BS in colon --> Diarrhea (this can happen if distal ileum is removed) |
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What is used to regulate bile flow?
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Choleretics
Cholagogues |
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What are choleretics?
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Agents that cause the LIVER to secrete a larger volume of bile
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What are cholagogues?
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Agents that cause an increase in the emptying of the GALL BLADDER (causes GB to contract, relax sphincter of Oddi)
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What is the law of reciprocal activity?
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Contraction of GB and relaxation of Oddi (and vice versa)
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What happens in the intestinal phase of secretion?
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Most secretions begin, as meal enters the intestine
Main secretion |
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What effect does the vagus have on the: liver, GB contraction/sphincter relaxation, pancreas low vol/high enz, pancreas highvol/low enz
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Vagus: involved in cephalic and gustatory
Liver: weak choloretic agent GB cont: Powerful contraction Pancreas low vol/high enz: +++ Pancreas high vol/low enz: -- low pH |
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What effect does the gastrin have on the: liver, GB contraction/sphincter relaxation, pancreas low vol/high enz, pancreas highvol/low enz
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Low effect on all of them
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What effect does the CCK have on the: liver, GB contraction/sphincter relaxation, pancreas low vol/high enz, pancreas highvol/low enz
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CCK: secreted in response to fat, inhibits gastric emptying
No effect on liver and highvol/low enz: no effect GB cont/pancreas low vol/high enz: high effect (contract GB to release concentrated BS + lipases from pancreas) |
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What effect does the secretin have on the: liver, GB contraction/sphincter pancreas low vol/high enz, pancreas highvol/low enz
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Liver: +
Pancreas:high vol/low enz: +++ high pH GB cont/pancreas ow vol high enz: low |
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What effect do bile salts have on the: liver, GB contraction/sphincter relaxation, pancreas low vol/high enz, pancreas highvol/low enz
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Liver: +++
Low for all the others |
