Lipid transport

Question 1

Describe the whole of lipid transport

Answer 1

1. Dietary lipids emulsified by bile in the SI where Pancreatic Lipases breaks down the lipids into FAs and glycerol
2. The FAs and glycerol are taken up into the epi cells where they are recombined into TAGs.
3. These TAGs get surrounded by phospholipids to form chylomicrons and these chylomicrons are then transported into lacteals that drain into the left thoracic vein
4. Enter circulation, to capillery beds, broken down by lipoprotein lipase to FAs and glycerol that are taken up by muscles and adipocytes
5. chylomicron leaves the capillary bed as chylomicron remnant. travels to the liver.
6. Lysosomal degration of the remnant to form cholesterol, glycerol and FAs
7. These form VLDL
   8Travel to capillery beds where broken down by lipoprotein lipase into glycerol and FAs
8. IDL is what remains
9. IDL either goes back to the liver for lysosomal degradation or is broken down further into FAs and glycerol. What is left now is LDL
10. LDL can either be taken up by peripheral tissue or can be oxidised

Question 2

How is LDL taken up by peripheral tissue?

Answer 2

Tissue requiring cholesterol express LDL receptors
LDL binds
Taken into cell by endocytosis
Lysosomes degrade the LDL

Question 3

What is the risk of having LDLs?

Answer 3

Increased likelihood of atherosclerosis
LDL can be oxidised
can cause CV diseases since macrophages–>foam cells

Question 4

Describe how HDL can be synthesised

Answer 4

1 of 2 ways
Nascent HDL synthesised in the liver and intestine
or
HDL bud of chylomicron or VLDL when digested by LPL

Question 5

What does HDL do?

Answer 5

Accumulates phospholipids and cholesterol from cells lining the blood vessels
So it removes cholesterol from cholesterol laden cells and returns it to the liver where its broken down and the cholesterol is used in bile salts

Question 6

What two ways can lipids be transported in blood?

Answer 6

Bound to albumin

Carried as lipoprotein particles

Question 7

Where do you get your cholesterol from?

Answer 7

Diet and synthesised in liver

Question 8

WHat is cholesterol used for? 3

Answer 8

Component of membranes
Precursor of steroid hormones
Precursor of bile acids

Question 9

Name 4 examples of steroid hormones

Answer 9

cortisol
aldosterone
testosterone
Oestrogen

Question 10

What are the 3 roles of apo lipoproteins?

Answer 10

Structural- Packages the lipids
functional- co factor for enzymes
ligand for cell surface receptors

Question 11

What are the three clinical signs of hypercholesterolemia?

Answer 11

tendon xanthomas- nodules on the tendon
Xanthelasmas- Yellow patches on the eyelids
Corneal arcus- white circle around the eye

Question 12

Whhat treatment do yoou use for hyperlipoproteinemias>

Answer 12

Firstly change diet and lifestyle
(Diet. Decrease cholesterol and saturated lipid. Increase fibre intake)
Then….
Drugs like statins and bile salt sequestrants (Binds to bile salts in the GI tract. forces liver to produce more bile acids so uses more cholesterol

Question 13

Describe the mechanism of action of statins?

Answer 13

Inhibits HMG-CoA reductase used in the synthesis of cholesterol