Atherosclerosis

Question 1

What is the main risk factor of atherosclerosis?

Answer 1

High cholesterol

Question 2

What is cholesterol essential for?

Answer 2

• production of steroids and fat-soluble vitamins
• maintaining membrane fluidity and permeability
• incorporating into cell membranes

Question 3

What is cholesterol carried in?

Answer 3

Cholesterol is highly insoluble so it is carried in lipoproteins:

• LDL
• chylomicron
• HDL
• VLDL
• IDL

Question 4

What are the clinical consequences of atherosclerosis?

Answer 4

• Myocardial Infarction
• Coronary artery disease
• carotid artery disease
• aneurysms
• peripheral artery disease

Question 5

Describe the exogenous pathway of cholesterol transport.

Answer 5

food stored in intestine > taken up as Chylomicron (CM) > CM travels in capillaries > LPL breaks it down to free fatty acids which is stored in adipose tissue > LPL breaks down CM reminant and expresses apoE protein > apoE protein binds to apoE receptor in liver and CM reminant is taken up by the liver as fatty acids and cholesterol.

Question 6

Describe the endogenous pathway of cholesterol transport.

Answer 6

free fatty acids and cholesterol in liver packaged into VLDL > VLDL travels in capillaries > LPL breaks it down to free fatty acids which is stored in the adipose tissue > LPL attacks VLDL and expresses IDL protein > IDL protein interacts with the liver and is converted into LDL > LDL travels in the plasma > peripheral tissues take up the LDL

Question 7

How do Statins act to lower cholesterol?

Answer 7

• competitive inhibitors of the rate-limiting step of cholesterol biosynthesis
• > decreases liver’s ability to generate cholesterol
• > stimulates LDL receptor up-regulation
• most effective at night since that is when most cholesterol biosynthesis occurs
• e.g. simvastatin, Pravastatin, Rosuvastatin

Question 8

what are the risk factors for atherosclerosis?

Answer 8

• Obesity
• Diabetes
• LDL-cholesterol
• High blood pressure
• High saturated fat diet

Question 9

what is the importance of liver in cholesterol regulation

Answer 9

• monitors levels of cholesterol
• regulates this through synthesis, absorption and bile secretion
• Drugs to treat hyperlipidaemia target this process in the liver