Lipid Metabolism and CVD

Question 1

what are the 2 key lipids

Answer 1

• cholesterol
• triacylglyceride

Question 2

how likely are you to come across key lipids clinically

Answer 2

• Xanthomata
• Xanthelasma
• Corneal arcus
• Milky blood/serum

Question 3

how likely are you to come across key lipids As cardiovascular disease risk factor

Answer 3

• Coronary heart disease
• Cerebrovascular disease
• Peripheral vascular disease
• As risk factor for acute pancreatitis (triglycerides)

Question 4

when are lipids measured in practise

Answer 4

• Total cholesterol (HDL + LDL + VLDL)
• HDL cholesterol
• Triglycerides as requested
• We calculate the total/HDL cholesterol ratio
• LDL cholesterol calculated as requested – if possible

Question 5

what are transported in the blood within lipoproteins

Answer 5

non-polar lipids

Question 6

what are lipoproteins

Answer 6

microscopic spherical particles consisting of:

• Hydrophobic core containing esterified cholesterol and triglycerides
• Hydrophilic coat comprising a monolayer of amphipathic cholesterol, phospholipids and one or more apoproteins

Question 7

what are apoproteins

Answer 7

they allow lipoproteins to bind to cells

• are recognized by receptors in the liver and other tissues

Question 8

how many classes of lipoproteins are there?

Answer 8

4

Question 9

what are the 4 classes of lipoproteins

Answer 9

• HDL particles: contain apoA-I and apoA-II
• LDL particles: contain apoB-100
• VLDL (very low-density lipoprotein): contain apoB-100
• Chylomicrons: contain apoB-48

Question 10

what do ApoB-containing lipoproteins do

Answer 10

Deliver TAGs to muscle for ATP biogenesis and adipocytes for storage

Question 11

what is LDL clearance dependent on

Answer 11

LDL receptors expressed by liver (most important) and other tissues

Question 12

what does Cellular uptake of LDL particles occurs via

Answer 12

receptor mediated endocytosis

Question 13

Within the cell, what is cholesterol released from

Answer 13

cholesteryl ester by hydrolysis

Question 14

what is the cause of Cardiovascular disease (atherosclerosis) cuased by elevated LDL and decreased HDL

Answer 14

diet
lifestyle
genetic factors

Question 15

Increased LDL →

Answer 15

pathogenesis of atherosclerosis

Question 16

what does HDL do

Answer 16

accepts excess cholesterol from plasma membrane of cells (e.g. macrophages) and delivers it to liver - reverse cholesterol transport

Question 17

what is the only organ that can remove cholesterol

Answer 17

the liver

Question 18

mechanism of action for statins

Answer 18

Block denovo synthesis of cholesterol, causing liver to upregulate LDL receptors

Question 19

what else do statins do other than lowering cholesterol

Answer 19

• Blocks pathway for producing cholesterol
• Act as competitive inhibitors of HMG-CoA reductase - rate limiting step in cholesterol synthesis in hepatocytes
• less cholesterol in cell
• Decrease in hepatocyte cholesterol synthesis causes a compensatory increase in LDL receptor expression and enhanced clearance of LDL

Question 20

what else does cholesterol prevent

Answer 20

• smooth muscle migration
• foam cell formation
• T cell activation
• adherance and aggregation of platlets and leukocytes