Theme 2: Lipids Flashcards
which lipoproteins are triglyceride rich?
chylomicrons and very low density lipoproteins
which lipoprotein is the main cholesterol carrier?
low density lipoproteins
what are the functions of apolipoproteins?
structural ligand binding receptor recognition activation/inhibition of lipolysis cholesterol efflux
what is the enzyme which removes free fatty acids from lipoproteins in circulation?
lipoprotein lipase
which lipoprotein delivers cholesterol to tissues?
LDL
which enzyme is involved in the conversion of IDL into LDL?
hepatic triglyceride lipase (HTGL)
which enzyme is the rate limiting enzyme in cholesterol synthesis?
HMG CoA reductase
what is the function of ABCA1 in reverse cholesterol transport?
transfers excess cholesterol from peripheral tissues to nascent HDL
which lipoprotein is involved in reverse cholesterol transport?
HDL
which lipoprotein is involved in the formation of atherosclerotic plaques?
LDL
what causes familial hypercholesterolaemia and what will be the results on a lipid profile?
reduction in receptor mediated clearance of LDL
lipid profile- elevated LDL, high total cholesterol normal fasting triglycerides
what causes familial combined hyperlipidaemia and what will be the results on a lipid profile?
overproduction of VLDL and apoB
lipid profile- elevated LDL, triglyceride and total cholesterol, may have low HDL
what causes remnant (type III) hyperlipidaemia and what will be the results on a lipid profile?
reduction in receptor mediated remnant clearance
lipid profile- elevated total cholesterol and triglycerides, cholesterol rich remnants present
what causes familial hypertriglyceridaemia and what will be the results on a lipid profile?
deficiency in lipoprotein lipase of apoCII
lipid profile- elevated triglyceride, may have low HDL
what is the mechanism of action of statins?
inhibits HMG-CoA reductase in cholesterol synthesis
up regulates LDL receptor expression which increases LDL clearance
net effect- —LDL,-TG,+HDL
what is the mechanism of action of fibrates?
agonists at PPAR-alpha receptor which regulates lipid metabolism. results in:
1. reduces TG and VLDL by increasing synthesis of lipoprotein lipase and stimulating fatty acid oxidation in liver
2. increases expression of apoA-I and apoA-II which increases HDL
3. increases hepatic LDL uptake
net effect- –VLDL, –TG, -LDL,+HDL
what is the mechanism of action of ezetimibe?
inhibits intestinal absorption of cholesterol by interfering with the NPC1L1 transport protein
net effect- reduces LDL and VLDL
what is the mechanism of action of cholestipol and cholestyramine?
they are bile acid binding resins which bind to bile acids in the gut preventing reabsorption and diverting hepatic cholesterol to bile acid synthesis. also causes increase in LDL receptors so LDL clearance increases
what is the mechanism of action of nicotinic acid?
- reduces VLDL synthesis
- reduces catabolic rate of HDL- increasing HDL
- activates lipoprotein lipase
net effect- -LDL,-VLDL, -TG, +HDL
