Cholesterol and Lipids

Question 1

Where is cholesterol found?

Answer 1

It is a precursor to steroid hormones, bile salts and vitamin D, a component of lipoproteins, found in atherosclerotic plaque and gall stones

Question 2

What are the 4 fates of cholesterol?

Answer 2

1. Transport (esterified and assembled into VLDL for transport to tissues)
2. Bile acids (used to emulsify fatty meals)
3. Steroid hormones and vitamin D
4. Membranes (makes them less fluid)

Question 3

How is cholesterol synthesised?

Answer 3

Acetyl-CoA is converted to mevalonic acid by HMG-CoA reductase (rate limiting step) which is then converted to cholesterol

Question 4

How is cholesterol carried around the body?

Answer 4

Esterified to make it more hydrophobic, and then incorporated into lipoproteins

Question 5

What are chylomicrons?

Answer 5

Formed in the intestinal mucosa, packages TAGs and cholesterol-ester from the gut into the tissues

Question 6

What are VLDLs?

Answer 6

Formed in the liver, carry TAGs from the liver to tissues via the blood

Question 7

What is LDL?

Answer 7

Low density lipoprotein, derived from VLDL, carries remaining cholesterol-ester to tissues
- circulates for longer, delivers more and more cholesteorl

Question 8

What is HDL?

Answer 8

High density lipoprotein, made in the liver and intestine
- good cholesterol involved in “reverse” cholesterol transport –> scavenges cholesterol from membranes and cells, acts on macrophages to stop them from becoming foam cells

Question 9

What is hypercholesterolaemia?

Answer 9

Increased total cholesterol in blood (above 6.2mM)

Question 10

What is hypertriglyceridaemia?

Answer 10

Increased blood levels of triglycerides