Lipoprotein Metabolism Flashcards
What happens when you remove cholesterol from a diet
The liver will start producing it
Are triglycerides, phospholipids and cholesterol soluble or insoluble in blood
Insoluble
What apolipoprotein do LDLs and VLDLs contain
Apolipoprotein B - looser to allow LDL particles to be bigger
What apolipoprotein do HDLs contain
Apolipoprotein A - lots of kinks, tight sphere
What do receptors in the liver bind to on lipoproteins
Apolipoprotein
What’s the role of lipoproteins
Carry fat in the bloodstream
What are VLDLs
Very low density lipoproteins
Features of VLDLs
Rich in TAG
> 30nm
Atherogenic (contribute to disease)
Features of LDLs
Rich in cholesterol
20-22nm
Atherogenic (contributes to disease)
Features of HDLs
Rich in protein and phospholipid
9-15nm
Anti-atherogenic (reverse disease process)
When is the production of the LDL receptor inhibited
When cholesterol accumulates
What happens to damaged cholesterol
It’s consumed by macrophages
How does HDL inhibit atherosclerotic process
- Inhibits expression of adhesion molecules
- Inhibits oxidation of LDL
- Promote cholesterol efflux (can take cholesterol out an artery and into liver)
What changes in the transport of TAG after eating
Increased circulating TAG -> Increased TAG transported as VLDL
Where do TAG-rich VLDLs unload TAG onto
Onto HDLs and LDLs
What catabolises TAG-rich HDLs
Kidney, leading to fewer HDLs
What does TAG get hydrolysed in
TAG-rich LDLs, leading to smaller and more dense LDLs (more dangerous)
What is postprandial lipaemia
The elevation of lipid in the circulation seen in the hours after eating a fat-containing meal
What happens to the intramuscular level of fat during exercise
It drops
Light exercise reduces TAG response after a moderate-fat meal
This could be driven by a number of mechanisms
- Greater LPL activity to restore intramuscular TAG
- Less hepatic VLDL secretion as more fat is being oxidised
- Greater blood flow to previously exercised muscle and the liver
How does training improve lipoprotein lipase activity in skeletal muscle and adipose tissue
- Improved delivery of FFA to active muscle
- Improved clearance of circulating triglycerides (postprandial). CVD patients show lower TAG clearance rates after a fatty meal
How does insulin resistance impact TG
Decreases TG clearance
Increases FFA release
This is particularly a problem in the post-prandial state
What does hormone sensitive lipase (HSL) do
Breaks stored TG and releases into circulation