Cholesterol Metabolism & Transport

Question 1

Why elevated cholesterol levels in blood is unhealthy (3)

Answer 1

1. Atheroscletotic plaques in arteries contain lots of of cholesterol and macrophages
2. Elevated levels of cholesterol correlates with coronary heart disease
3. People with mutation in receptor in LDL have elevated levels of plasma cholesterol in the form of LDL particles (higher risk of heart attack)

Question 2

Lipoprotein structure

Answer 2

A surface monolayer of phospholipids and free cholesterol, with a hydrophobic core of triglycerides and cholesterol esters, and apolipoproteins wrapping around the entire structure, which stabilize the structure.

Question 3

Measure of density of lipoproteins

Answer 3

More lipids = less density. Less dense lipoproteins tend to be larger.

Question 4

Origin and constitution of VLDL

Answer 4

From the liver, made of triglycerides

Question 5

Origin and constitution of IDL

Answer 5

From VLDL, made of triglycerides and cholesterol

Question 6

Origin and constitution of LDL

Answer 6

From IDL, made entirely of cholesterol

Question 7

Origin and constitution of HDL

Answer 7

From the liver and the intestine, made of cholesterol and phospholipids

Question 8

Origin and constitution of chylomicrons

Answer 8

From the intestine, made entirely of triglycerides

Question 9

Origin and constitution of chylomicron remnants

Answer 9

From chylomicrons, made of triglycerides and cholesterol

Question 10

How chylomicrons form

Answer 10

Fatty acids and monoglycerides emulsify as bile salts and enzymes remove bits. These form into mycelles and pass through the epithelial cells. Here they combine with proteins in the golgi apparatus to form chylomicrons.

Question 11

Path of chylomicrons after formation

Answer 11

They are released in bunches on the other side of the epithelial cells into the lymphatic vessel where they are broken down for repurposing

Question 12

How muscles are fed chylomicrons

Answer 12

Fatty acids broken down from chylomicrons using lipoprotein lipase. The glycerol is used by the liver.

Question 13

How adipose tissue is fed chylomicrons

Answer 13

Fatty acids and triglycerides broken down from chylomicrons by lipoprotein lipase

Question 14

What chylomicron remnants are used for

Answer 14

Digestion by liver

Question 15

Why chylomicron remnants are smaller than chylomicrons

Answer 15

A protein is removed that is used by lipoprotein lipase