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WVSOM - Biochem
Lipoproteins
Question | Answer |
---|---|
What kind of diet decreases LDL Levels | Low cholesterol diets |
High HDL levels are a ______________ risk factor for coronary heart disease. | negative |
What decreases HDL levels? | smoking |
What increases HDL levels | exercise |
Serum trigylceride levels are proportional to ___________ | VLDL levels in a fasted condition |
APO C-II | cofactor activator of lipoprotein lipase (LPL) |
APO-E | ligand for binding of several lipoproteins to the LDL receptor |
Lp(a) | used to predict coronary heart disease |
3 Lipoprotein subclasses | VLDL-C LDL-C HDL-C |
chylomicrons | transport dietary lipids to where they need to go |
Chylomicrons only occur in the __________ state. | fed |
Chylomicrons synthesis occurs | outside the liver in the intestinal epithelial cells |
Very Low Density Lipoproteins carry hepatically synthesized TG to | skeletal muscles and adipose cells |
VLDL are made in the _____________. | Liver |
HDL donates ______ to VLDL to activate ___________. | Apo CII; LPL |
Lipoprotein synthesis induced by | insulin |
VLDL that leaves the liver | was synthesized in the liver or delivered to teh liver from teh diet by chylomicron remnants |
VLDL becomes | IDL |
IDL becomes | LDL |
IDL | Intermediate Density Lipoprotein |
IDL are turned to LDL in the __________ | liver |
IDL is recognized in the liver by | hepatic LDL receptors |
Conversion of IDL to LDL (3) | 1. Core TG are removed from IDL increasing density 2. Cholesterol esters are transferred from HDL to IDL (uses LCAT) 3. TG are transferred from IDL to HDL to make it more dense LDL |
LDL delievers cholesterol to ____________ | extra hepatic cells |
LDL comes from | some comes from the VLDL and some comes from the HDL addition of cholesterol ester to the IDL as they become LDL |
Uptake of LDL by extra-hepatic cells occurs via | LDL receptors on the cell's surfaces |
De-esterified cholestol delevered by LDL inhibits synthesis of | HMG-CoA reductase |
Inhibiting HMG-CoA reductase results in | extra-hepatic cholesterol synthesis |
LDL utilization in extra-hepatic cells | some is esterified by ACAT |
Deficits in extra hepatic LDL receptors limit | extra-hepatic LDL uptake |
LDL delivers cholesterol to _____________. | extra-hepatic cells |
IDL density in comparison | VLDL < IDL < LDL |
de-esterified cholesterol leads to _________ | down regulation of the genes for LDL receptor synthesis |
Down regulation of LDL receptor synthesis allows _______________ | entry into the cell of only the amount of cholesterol needed |
LRP | LDL receptor-related protein |
LRP function | recognizes a wider range of lipoproteins adn lipoprotein fragments than does teh LDL receptor |
LRP differs from LDL receptor because __________ | it is not affected by cellular cholesterol levels |
LRP may help ____________ | decrease serum lipoprotein levels |
Familial Hypercholestemia | genetically defective LDL receptors occur and LDL levels become extremely high |
95% of elevated LDL levels caused by _______ | multifactorial hypercholesterolemia due to a combination of dietary, behavioral, and genetic factors |
Elevated HDL levels correspond with a | decrease risk of coronary heart disease |
Where are HDL synthesized? | Liver |
Roles of HDL (3) | HDL activate Lipoprotein Lipase Pick up cholesterol resulting from cell membrane degradation Retrun some cholesterol directly to the liver |
How to control serum LDL levels | limiting dietary cholesterol and saturated and trans fatty acids; depends on genetic make up |
Pharmachological treatment of lowering LDL | statin drugs inhibit HMG CoA reductase Bile and cholesterol sequestering drugs decrease bile acid reabsorption and dietyar cholesterol absorption |
Lipoprotein (a) | Lp(a) thought to be a marker or predictor for cardiovascular disease |
Lp (a) found to be elevated ___________ | post-MI |
Lp(a) promotes ________ when oxidized | atherosclerotic plaque formation |
New research findings indicate (2) | 1. lipoproteins themselves are the risk factor 2. HDL and LDL are not each a specific Lipoprotein but rather occur in sub types |
Sub-types of lipoproteins are associated with | amounts of risk of coronary heart disease |