B1 Cholesterol

Question 1

Major risk factors of coronary heart disease (7)

Answer 1

Age/ male
Smoking 
Hypertension 
High LDL-C/ Low HDL-C
Diabetes
Fam history: premature coronary HD, peripheral vascular disease or stroke

Question 2

Liver: describe role of

1. Hepatic artery
2. Portal vein

Answer 2

1. supplies 25% of total blood flow & most of required O2

2. drains most of GI. Supplies 75% of blood & transport recently absorbed material from intestines to liver

Question 3

Functions of Liver

Answer 3

protein, carbohyrdate & lipid homeostasis
Stores glycogen, Vitamins & iron
Contains reticuloendothelial system for the synthesis and breakdown of blood cells.
Metabolise, detoxify & excrete endogenous and exogenous compounds (incld. drugs & toxins)

Question 4

What is a good range for HDL-C, LDL-C and Triglycerides

Answer 4

1. > 1mmol/L
2. <2-3mmol/L
3. <1.7mmol/L

Question 5

Describe cholesterol

• where is it found in the body
• where is majority synthesised
• where does the rest come from

Answer 5

Waxy, fat-like substance
Steroid alcohol (sterol)
Found in all cells of the body
75% of cholesterol is synthesized in liver (in the cytoplasm & ER)
((Small amounts are synthesized by the lining of the small intestine and the individual cells of the body))
25% comes from diet (de novo: new synthesis)

Question 6

what is the rate limiting step of cholesterol production

- what drug can block

Answer 6

HMG-CoA Reductase
- Statins
prevents conversion to mevalonic acid etc.
Ultimately prevents cholesterol formation & biproducts

Question 7

What does Triparanol do?

Answer 7

Inhibits late step in pathway (desmosterol).

W/drawn from market due to side effects: lead to desmosterol accumulation

Question 8

what is cholesterol used for

Answer 8

1. Cell membranes: builds & maintains
2. Sex hormones: e.g. progesterone, estrogen & testosterone
3. Hormones released by the adrenal gland: e.g. cortisol & aldosterone
4. Production of bile acids: digestion in intestine
5. Vitamin D: synthesises from sun light
6. Insulates nerve fibres

Question 9

Describe role of

1. Chylomicrons
2. VLDL
3. IDL
4. LDL
5. HDL

Answer 9

1. Carry triglycerides (fat) from the intestines —> liver —> skeletal muscle —> adipose tissue
2. Carry (newly synthesised) triglycerides from liver —> adipose tissue
3. intermediate between VLDL and LDL (not ~detectable in blood)
4. Carries cholesterol to cells from liver (too much carried = harmful buildup: arterial disease)
5. Takes cholesterol away from the cells and back to the liver ((prevents arterial disease))

Question 10

Where are oral drugs typically absorbed

Describe first pass metabolism

Answer 10

1. small intestines
2. Drug gets metabolized at a specific location in the body that results in a reduced concentration of the
   active drug upon reaching its site of action or the systemic circulation.