Term
what's the most important enzyme to start cholesterol synthesis?
what does it convert to what?
which drugs inhibit it?
how is it activated / inactivated?
what hormone stimulates activation? |
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Definition
HMG-CoA
converts Acetyl-CoA to Mevalonate
statins inhibit it
activated by dephosphorylasing by HMG-CoA reductase phosphorylase
inactivated by protein kinase that adds a phosphate
activated by insulin |
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Term
what does SREBP (sterol regulatory element binding protein) do?
what acts as negative feedback for it? |
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Definition
it stimulates synthesis of the enzyme HMG-CoA reductase
cholesterol acts as negative feedback |
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Term
what are the two Primary bile acids?
which enzyme is the rate limiting step for bile acid synthesis? what does the enzyme do? |
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Definition
Glycocholic acid & Taurocholic acid
7α-hydroxylase (adds an OH group to cholesterol) |
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Term
how is 7α-hydroxylase negatively regulated?
what hormone & enzyme does it require for activation? |
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Definition
neg regulation by bile acids
requires thyroid hormones & Vit C
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Term
how does the body get rid of excess cholesterol?
what's the role of bile acids in this? (3 functions) |
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Definition
through feces
bile acids solubilize cholesterol preventing precipitation of it into gallbladder
they also act as emulsifying agents making dietary triacylglycerides accessible to pancreatic enzymes
they facilitate intestinal absorption of fat-soluble vitamins |
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Term
what are the three symptoms of an obstructed bile duct?
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Definition
pale (lack of bile) floating stools (high fat content)
Itching: bile in blood stream
jaundice: conjugated bilirubin |
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