Lipoproteins: Blood Transport

Question 1

What helps in the transportation of long chain and very long chain free FA from adipocytes to other tissues?

Answer 1

Albumin

Question 2

What do lipoproteins consist of?

How are they bonded?

Answer 2

TG, C, CE, phospholipids

Non-covalently

Question 3

Why does HDL have highest density?

Answer 3

Because they have highest protein content and protein weighs more than lipids

Question 4

Why does chylomicron and VLD have the two lowest densities?

Answer 4

Because they have the highest TG composition and TG weighs less than other components such as proteins

Question 5

Where do TG found in chylomicrons come from?

Answer 5

The diet

Question 6

Where do TG found in VLDL come from?

Answer 6

biosynthsis

Question 7

Where are chylomicrons produced?

Answer 7

In intestinal epithelial cells from dietary fats

Question 8

Where are VLDL produced?

Answer 8

In the liver mainly from dietary carbohydrate

Question 9

What are the major functions of chylomicrons?

Answer 9

Carries TG in the blood

Question 10

What are the major functions of VLDL?

Answer 10

Carries TG in the blood

Question 11

What are the major functions of HDL?

Answer 11

1. Returns cholesterol from peripheral tissues to the liver

2. Exchanges proteins and lipids with other lipoproteins

Question 12

What are the major functions of apoB-100

Answer 12

ligand for LDL receptor

secretion of VLDL

Question 13

What are the major functions of apC-II?

Answer 13

Activator of lipoprotein lipase

Question 14

What is the function of LPL in lipoprotein metabolism?

Answer 14

processing of chylomicrons and VLDL

Question 15

What is the function of HTGL (hepatic TG lipase) in lipoprotein metabolism?

Answer 15

Converts IDL to LDL

Question 16

What is the function of LCAT in lipoprotein metabolism?

Answer 16

catalyzes transfer of long chain fatty acids to cholesterol, forming CE

Question 17

What is the function of ACTA in lipoprotein metabolism?

Answer 17

intracellular enzyme that esterifies cholesterol

Question 18

Does insulin stimulate of inhibits synthesis and secretion of LPL?

Answer 18

Stimulates

Question 19

Which apoprotein activates LPL?

Answer 19

apo-CII

Question 20

Where is ACAT found?

Answer 20

in cells

catalyzes C to CE

Question 21

Where is LCAT found?

Answer 21

In the blood

Question 22

Why is LDL bad?

Answer 22

Oxidized LDL produces foam cells from macrophage
Foam cells form fatty streaks
Foam cells are the first step in atherosclerosis

Question 23

How does fatty streaks lead to plaques?

Answer 23

• Extensive formation of fatty streaks causes further endothelial damages
• Damaged endothelial cells release TXA2
• TXA2 promotes platelet aggregation
• Platelets and macrophages at the site of injury can release growth factors
• Cells secrete fibrous material (plaque) that forms a cap
• Macrophage cells are trapped by the fibrous cap and dies

Question 24

How do plaques lead to blood cloths?

Answer 24

• calcification occurs in the cap
• this forms a thick and tough deposit
• when rupture and hemorrhage of the plaque occurs, a blood clot or thrombus is formed
• this can further block blood vessels causing a MI

Question 25

How do statins work to lower LDL?

Answer 25

• Statin inhibits cholesterol synthesis
• There is down regulation of intracellular cholesterol
• This causes upregulation of LDL-receptors which reduces the amount of LDL in the blood
• This is followed by down regulation of serum cholesterol; intracellular cholesterol homeostasis