Dyslipidemias Flashcards
Importance of cholesterol:
-membrane structure and function + maintenance
Cholesterol is a precursor for:
- cholesteryl acids (storage/cartage?)
- bile acids (digestion/absorption; solubilize cholesterol in gall bladder; major route to eliminate cholesterol
- steroid hormones
- Vit D
Sources of cholesterol:
- 50% diet
- 50% endogenous biosynthesis
Sites of cholesterol biosysntesis
- liver 50%
- other tissues (intestines, skin, adrenal cortex, reproductive tissues) 50%
Role of liver regarding cholesterol:
- major site of biosynthesis
- major distribution point for cholesterol
- Liver HMG-CoA reducatase –> affected by statins
- major route for cholesterol elimination from the body (conversion to bile acids)
role of plasma lipoproteins:
- delivery of lipids (TAAGs, cholesterol, cholesterol esters) to the body
- shelter these hydrophobic lipids from water
Mechanisms for delivery of lipids to cells- fatty acids of TAGs:
- fatty acids from TAGs are released from lipoproteins by lipases (LPL and HL) in capillary walls
- free FA are then absorbed by cells
Mechanism for delivery of lipids-cholesterol, cholesteryl esters, and unhydrolyzed TAGs:
- endocytosis of the lipoprotein after binding to surface cell receptor
- degraded in lysosomes
Synthesis site for chylomicrons
-enterocytes
Synthesis site for VLDLs
-liver
Synthesis site for IDLs
-in circulation for VLDLs
Synthesis site for L:DLs
-in circulation from IDLs
Synthesis site for HDLs
- 80% liver
- 20% intestine
Chylomicrons
- major components
- major role:
- 88% TAGs
- 4% cholesterol/cholesteryl esters
-Dietary TAGs to tissues & remnants to liver
VLDL
- major components
- major role:
- 50% TAGs
- 23% cholesterol/cholesteryl esters
-TAGs FROM the liver
IDL
- major components
- major role:
- 29% TAGs
- 43% cholesterol/cholesteryl esters
-more dense
- C, CE TO liver
- converted to LDL
LDL
- major components
- major role:
- 13% TAGs
- 58% cholesterol/cholesteryl esters
- more more dense!
- C and CE TO liver and extra hepatic tissues
HDL
- major components
- major role:
- 13-16% TAGs
- 35-41% cholesterol/cholesteryl esters
- MOST DESIRABLE - we want to get rid of cholesterol
- C and CE FROM extra-hepatic tissues TO liver (reverse C and CE transport)
reverse cholesterol is:
bringing back to liver- get rid of cholesterol
Lipoprotein lipase (LPL)
- location
- role
- capillary walls
- hydrolyzes TAGs in chylomicrons, VLDLs, and IDLs
- induced by insulin
Hepatic lipase (HL) -role?
-hydrolyses TAGs in IDLs to LDLs
Lecithin (PC) - Cholesterol Acyl transferase (LCAT)
- where?
- role?
- on HDLs
- transfers fatty acids from lecithin to C to form CE in HDLs
- C is kept in lipoprotein monolayer
Apo B-100
- found in?
- role?
- VLDLs
- IDLs
- LDLs
-Binds LDL receptor
Apo B-48
- found in?
- role?
- chylomicrons and remnants
- structural role
ApoE
- found where?
- role?
- Chylomicrons
- VLDLs
- IDLs
- HDLs
- Binds LDL receptor
- reservoir on HDLs
Apo C-11
- found where
- role?
- Chylomicrons
- VLDLs
- IDLs
- HDLs
- activates lipoprotein lipase
- reservoir on HDLs
Apo A-1
- found where?
- role?
- HDLs
- activates LCAT
Which particle brings cholesterol back to liver for excretion or whatever?
- HDL
- IDL (can also take away from liver)
- LDL (can also take away from liver)
Which particle brings cholesterol away from the liver for use?
- VLDL
- IDL (can also bring back to liver)
- LDL (can also bring back to liver)
