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37 Cards in this Set
- Front
- Back
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how many carbons does cholesterol contain
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27
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how many double bonds are in cholesterol
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1
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what is the polar part of cholesterol
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the OH group
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how many rings are in cholesterol
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4
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what is cholesterol a precursor to
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bile acids, vitamin D, steroids
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what cholesterol a component of
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gall stones
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what % of cholesterol circulates as a free molecule
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30%
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what does the other % of cholesterol circulate as
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the other 70% circulates on long chain FA
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how does cholesterol circulate
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via lipoproteins
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what is the committed step of cholesterol synthesis
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HMG CoA reductase
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what is the rate limiting enzyme in cholesterol biosynthesis
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HMG CoA reductase
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what are the activators of HMG CoA reductase
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fasting, insulin, T3
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what are the inactivators of HMG CoA reductase
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high intake of cholesterol, glucagon, cortisol
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where does cholesterol biosynthesis occur
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in the cytosol
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what is the major organ of cholesterol biosynthesis
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liver (main), but also occurs in intestin, and adrenal cortex
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what do statin drugs do
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inhibit HMG CoA reductase from making cholesterol
reduce amount of LDL increase activity of LDL receptors |
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what is the stored form of cholesterol
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cholesterol ester
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what are the ways intracellular cholesterol is regulated
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statin drugs can inhibit HMG CoA reductase thereby inhibiting amount of intracellular cholesterol made
high amounts cholesterol can also inhibit HGM CoA reductase and the LDL receptors |
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where are bile acids synthesized
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the liver
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info on primary bile acids
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synthesized in liver
stored in gall bladder/duodenum |
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secondary bile acids info
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formed in intestine by bacterial enzymes
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what happens to bile acids at physiological pH
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they form Na or K salts
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what are one of the functions of bile acids
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bile acids emulsify ingested lipids into globules aiding absorption of dietary fats
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how is cholesterol in bile
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cholesterol is present in high concentrations in bile
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what forms the micelles
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cholesterol forms the micelles with phospholipids and bile acids
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how are gall stones formed
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when the liver secretes bile into the gall bladder if it has a ratio of cholesterol/phospholipid greater than 1 then gall stones form
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facts on gall stones
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occurs in 20% of population
can be removed via surgery cause abdominal pain |
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what is the precursor for all steroid hormones
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cholesterol
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where does biosynthesis of steroids occur
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adrenal cortex, testis, ovary
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what are the 3 major steroids
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corticosteroids (cortisol[glucocorticoids] and aldesterone [minerialcorticoids])
adrogens (testis) estrogens (ovary) |
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what do steroids all do
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they all act via binding to nuclear receptors thereby starting transcription which leads to protein synthesis
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where are steroids secreted
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urine
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what is vitamin D derived from
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cholesterol
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where are the majority of Vit D obtained
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majority is produced by malpighian cells via sun reaction small amount taken up from food
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where is vitamin D modified
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liver and kidney
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how is Vit D transported
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transported through plasma via vit D binding proteins
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what is another name for Vit D
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cholecalciferol
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