Cholesterol - Cholesterol Transportation

Question 1

Lipoprotein anatomy

Answer 1

Phospholipid mono layer containing cholesterol and apoproteins

Surround a core of cholesterol esters and triacyclglycerols

Question 2

Cholesterol esters

Answer 2

Synthesised in plasma form cholesterol and the acyl chain of phosphatidycholine

Enzyme: lecithin:cholesterol acyltransferase (LCAT)

Question 3

VLDLs

Answer 3

Synthesised in the liver —> released into circulation

Question 4

HDLs

Answer 4

Synthesised in liver and small intestines
—> take pub lipids and cholesterol from tissues back onto the the liver

“Good cholesterol” —> take cholesterol from peripheral tissues back to the liver for use or disposal
—> help lower total serum cholesterol

Question 5

IDLs

Answer 5

Formed by triacylglycerol removal from VLDs

Question 6

LDLs

Answer 6

Formed by cholesterol ester transfer from HDL to IDL

“Bad cholesterol” —> prolonged elevation of LDL levels leads to atherosclerosis
—> transport cholesterol from liver to peripheral tissues

More than 40% of their weight mad eux of cholesterol esters

Question 7

LDL and Familial hypercholesterolaemia

Answer 7

Inherited as a monogénisme dominant trait

SINGLE copy of gene —> level 2-3 times > —> susceptible to atherosclerosis in middle age

BOTH copies of gene —> 5x > —>severe atherosclerosis and coronary infarcts may occur in adolescence

Question 8

Controlling hypercholesterolaemia

Answer 8

1) inhibit de novo synthesis of LDL —> HMG-CoA-Reductase inhibitors —> statins

2) lower cholesterol absorption in gut —> resins or sequestrants
—> bind or sequester bile acid-cholesterol complexes preventing their réabsorption by the intestine