Lipid metabolism

Question 1

How are non-polar lipids transported in the blood?

Answer 1

Lipoproteins

Question 2

What is the structure of a lipoprotein?

Answer 2

Microscopic spherical particle
Hydrophobic core containing esterified cholesterol triglycerides.
Hydrophilic coat made up of a monolayer of amphipathic cholesterol, phospholipids and apoproteins.

Question 3

What are the major lipoproteins?

Answer 3

HDL
LDL
VLDL
Chylomicrons

Question 4

What is the function of ApoB-containing lipoproteins?

Answer 4

Deliver triglycerides to muscles for ATP biosynthesis and adipocytes for storage

Question 5

What type of lipoprotein transports dietary triglycerides?

Answer 5

Chylomicrons formed in the intestinal cells

Exogenous pathway

Question 6

What type of liporprotein transports triglycerides formed in the liver?

Answer 6

Very low density lipoproteins

Endogenous pathway

Question 7

Describe the life cycle of ApoB-containg lipoproteins

Answer 7

Assembly - in the liver and intestine
Intravascular metabolism
Receptor mediated clearance

Question 8

What causes the activation of chylomicrons and VLDL particles?

Answer 8

Transfer of apoCII from HDL particles

Question 9

How are LDL particles cleared?

Answer 9

LDL is cleared by many organs, but the most important is the liver.
There is cellular uptake of LDL particles via receptor-mediated endocytosis.
Cholesterol is released.
This causes inhibition of HMG-CoA reductase which reduces cholesterol synthesis by the liver and storage of cholesterol as an ester.

Question 10

Why is LDL ‘bad’ cholesterol?

Answer 10

When the endothelium of a blood vessel is injured, LDL in the blood enters into the intima of the artery. An atheromatous plaque forms.

Question 11

Why is HDL ‘good’ cholesterol?

Answer 11

It has a key role in removing excess cholesterol and returning it to the liver where it can be eliminated.

Question 12

Define dyslipidaemia

Answer 12

Elevated total or low-density lipoprotein (LDL) cholesterol levels, or low levels of high-density lipoprotein (HDL) cholesterol.

Question 13

How does primary dyslipidaemia occur?

Answer 13

Through a combination of diet and genetic factors

Question 14

How does secondary dyslipidaemia occur?

Answer 14

Consequence of other diseases

Question 15

How is primary dyslipidaemia classified?

Answer 15

Frederickson Classification

Types I-V

Question 16

What is the class of lipid-lowering drugs?

Answer 16

Statins

Question 17

Name two statins

Answer 17

Simvastain and atorvastatin

Question 18

What to stains do?

Answer 18

The lower LDL, reduce triglycerides and increase the amount of HDL.
They block an enzyme (HMG-CoA reducase) responsible for the synthesis of cholesterol in the liver. Make the liver more readily able to remove LDL from the plasma. They INCREASE CLEARANCE.

Question 19

When are statins taken?

Answer 19

At night

Question 20

What is the first line drug in patients with very high triglyceride levels?

Answer 20

Fibrates

Question 21

Give two examples of fibrates

Answer 21

Bezafibrate and gemfibrozil

Question 22

Describe drugs that inhibit cholesterol absorption

Answer 22

Bile acid binding resins that cause the excretion of bile salts resulting in more cholesterol to be converted to bile salts

Question 23

Give examples of bile acid binding resins

Answer 23

colestyramine, colestipol, colsevelam

Question 24

Name a drug that decreased LDL with little change in HDL

Answer 24

Ezetimibe