Lipoproteins: Blood Transport Flashcards
What helps in the transportation of long chain and very long chain free FA from adipocytes to other tissues?
Albumin
What do lipoproteins consist of?
How are they bonded?
TG, C, CE, phospholipids
Non-covalently
Why does HDL have highest density?
Because they have highest protein content and protein weighs more than lipids
Why does chylomicron and VLD have the two lowest densities?
Because they have the highest TG composition and TG weighs less than other components such as proteins
Where do TG found in chylomicrons come from?
The diet
Where do TG found in VLDL come from?
biosynthsis
Where are chylomicrons produced?
In intestinal epithelial cells from dietary fats
Where are VLDL produced?
In the liver mainly from dietary carbohydrate
What are the major functions of chylomicrons?
Carries TG in the blood
What are the major functions of VLDL?
Carries TG in the blood
What are the major functions of HDL?
- Returns cholesterol from peripheral tissues to the liver
2. Exchanges proteins and lipids with other lipoproteins
What are the major functions of apoB-100
ligand for LDL receptor
secretion of VLDL
What are the major functions of apC-II?
Activator of lipoprotein lipase
What is the function of LPL in lipoprotein metabolism?
processing of chylomicrons and VLDL
What is the function of HTGL (hepatic TG lipase) in lipoprotein metabolism?
Converts IDL to LDL
What is the function of LCAT in lipoprotein metabolism?
catalyzes transfer of long chain fatty acids to cholesterol, forming CE
What is the function of ACTA in lipoprotein metabolism?
intracellular enzyme that esterifies cholesterol
Does insulin stimulate of inhibits synthesis and secretion of LPL?
Stimulates
Which apoprotein activates LPL?
apo-CII
Where is ACAT found?
in cells
catalyzes C to CE
Where is LCAT found?
In the blood
Why is LDL bad?
Oxidized LDL produces foam cells from macrophage
Foam cells form fatty streaks
Foam cells are the first step in atherosclerosis
How does fatty streaks lead to plaques?
- 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
How do plaques lead to blood cloths?
- 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
How do statins work to lower LDL?
- 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
