Reddy's Lipid Metabolism Flashcards
What makes up the outer layer of plasma lipid particles (LDL, chylomicrons, etc)?
- amphipathic phospholipids
- unesterified cholesterol
- Apolipoproteins
What makes up the core of plasma lipid particles (LDL, chylomicrons, etc)?
- Triglycerides
- cholesterol esters
What are the lipoprotein risk factors for coronary heart disease?
- High LDL
- Low HDL
All of the following plasma lipid particles contain cholesterol. Which cholesterol is considered ‘HEALTHY / GOOD’ cholesterol?
A. Chylomicrons B. VLDL (Very Low Density Lipoprotein) C. HDL (High Density Lipoprotein) D. IDL (Intermediate Density Lipoprotein) E. LDL (Low Density Lipoprotein)
C. HDL
What are the major functions of cholesterol?
- alters fluidity of cell membranes
- starting material for bile acids
- starting material for steroid hormones
Where is the unsaturated fatty acid located on glycerol of a TAG?
-second carbon
What does phospholipase A2 do?
- releases arachidonic acid from cell membranes
- inhibited by steroids
What does the drug Orlistat do?
- inhibits intestinal lipases
- more lipids end up in feces instead of entering body
What does the drug Ezetimibe do?
- prevents cholesterol absorption in the intestine
- Can be used with other drugs to help lower cholesterol
What type of fatty acids are essential? What do we need them for?
- cis-polyunsaturated fatty acids
- needed to make local hormones and increase cell membrane fluiditiy
How are Trans-fats formed?
- artificially
- hydrogenation of oils
- cooking for a long time at high temperatures
What do apolipoproteins do?
-help in packaging, transport, binding to receptors of enzymes for chylomicrons etc.
What particle adds apolipoproteins to chylomicrons?
-HDL
What does apolipoprotein C do?
-helps in docking VLDL and chylomicrons in tissues and activating lipoprotein lipase
What does apolipoprotein E do?
-recognizes receptors and helps in lipid particle uptake by the liver
What does HDL do?
- adds lipoproteins to lipid particles
- picks up cholesterol from periphery and delivers to liver for elimination
- transfers fatty acids from VLDL to liver
HDL cholesterol is considered ‘HEALTHY / GOOD’ cholesterol.
The reason is:
A. HDL is small in size and has high density
B. HDL tags Zip codes, thus help remove lipids from plasma
C. HDL is made both in liver and intestine while VLDL is made only
in liver
D. HDL transfers cholesterol from peripheral tissues (via plasma)
to liver for excretion / reuse
E. HDL contains Apolipoproteins
TWO correct answers
-
What does LDL do?
-delivers cholesterol to the peripheral tissues and liver
What do VLDLs do?
-deliver de novo TAG to peripheral tissues
What is the effect of lower concentration of choleterol in cells on LDL receptors?
- leads to more LDL receptors so that more LDL from plasma can be taken up and increase cellular cholesterol levels
- more LDL receptors is good because plasma cholesterol levels will go down
Where does the liver get its cholesterol?
- makes it from acetate
- picks up from plasma (LDLs etc)
How do LDLs lead to atherosclerosis?
- damaged endothelial wall allows cholesterol-rich LDL to inflitrate wall
- macrophages in the intima take up cholesterol and fibroblasts proliferate = wound response
- macrophages release cytokines, leukocytes are recruited
- ulceration of the plaque area promotes thrombosis formation leading to obstruction and infarction
What is the main contributor to plaque in the arteries?
-circulating LDL
What are the two ways in which we excrete cholesterol?
- Free cholesterol with feces
- bile acids lost in feces
