1. KA 7d: Learning Outcomes
State where cholesterol is synthesised
State the type of diet that can increase cholesterol levels in the blood
Give 2 reasons why cholesterol is important for cellular functions
Define HDL and LDL
Describe the role of HDL in the body
Describe the role of LDL in the body
Describe the effect of the of the negative feedback response when a cell has sufficient cholesterol levels
State what a high HDL to LDL ratio may result in
Describe 2 lifestyle choice which can improve the health of an individual
Describe the role of ‘statins’

2. Tasks: Watch the following video:
Answer the Qs on the sheet as you watch it!
Once you have finished, go round 3 other people to fill in any missing answers (you have 1 minute!)

3. Why is cholesterol so bad?
Higher blood cholesterol level = higher risk of heart disease
Most cholesterol is synthesised by the liver from saturated fats in the diet (but every cell can also produce cholesterol) = if you have high cholesterol already, it will increase further because your body can also make more! -
– answers TV

4. Why is cholesterol so good?
Component of the cell membrane
Precursor for steroid synthesis
natural steroid hormones are generally synthesised from cholesterol in the gonads and adrenal glands -
– answers TV

5. What are LDLs and HDLs? Essentially, they are TRANSPORTERS
Insoluble cholesterol must combine with proteins to form soluble LIPOPROTEINS to be transported in blood
Two major transport lipoproteins:
HIGH DENSITY LIPOPROTEINS (HDLs)
LOW DENSITY LIPOPROTEINS(LDLs)

6. Low Density Lipoproteins
Main cholesterol carriers in blood, transports cholesterol made by liver to body cells.
Body cells have LDL receptors
When LDL-cholesterol complex attaches it is engulfed and then used by the cell

7. Low Density Lipoproteins

8. Low Density Lipoproteins
Body cell has sufficient cholesterol
Negative feedback is triggered
Inhibits the synthesis of new LDL receptors
Less LDL taken up by body cells, so more is left circulating in blood vessels!
Endothelial cells now take up cholesterol and cholesterol deposited in artery walls … ATHEROSCLEROSIS!

9. High Density Lipoproteins
HDLs transport cholesterol from body tissues to liver to be broken down
Prevents high level of cholesterol build up in blood stream (lowers blood cholesterol levels and helps remove plaque, so does not contribute to atherosclerosis)
HDL known as ‘good cholesterol’
However a balance of HDL and LDL required…

10. High Density Lipoproteins
Normal cholesterol carried by:
HDL – 20-30%
LDL – 60-70%
A higher ratio of HDL to LDL will result in lower blood cholesterol and a reduced chance of atherosclerosis.
Reverse is also true

11. Treating High Cholesterol - STATINS
Most effective drugs in lowering cholesterol levels in the blood
Method 1:
Statins reduce blood cholesterol by inhibiting the synthesis of cholesterol by liver cells

12. Treating High Cholesterol - STATINS
Most effective drugs in lowering cholesterol levels in the blood
Method 2:
Competitive inhibition with an enzyme which makes cholesterol (statin competes with active site thus not allowing original molecule to enter – so overall decreasing the amount of cholesterol).

13. Familial Hypercholesterolaemia (FH)
Autosomal Dominant gene
Only 1 ‘faulty’ allele required
Causes:
Decreased LDL receptors on cells
Change in receptor shape on cells
Genetic testing can determine if the FH gene has been inherited
Treatments:
Lifestyle modification of diet - reducing fats and oils
Medication – statins
Extreme treatment – filtration of blood

14. B

15. Summary - Treatments and Drugs
Regular physical activity tends to raise HDL levels, dietary changes aim to reduce the levels of total fat in the diet and to replace saturated with unsaturated fats.
Drugs such as statins reduce blood cholesterol by inhibiting the synthesis of cholesterol by liver cells.

16. Cholesterol is synthesised by all cells, although 25% of total production takes place in the ______. A diet high in ________ fats or cholesterol causes an increase in cholesterol levels in the blood. Cholesterol is a component of cell _________ and a precursor for _________ synthesis.
HDL transports excess cholesterol from the body cells to the _________ for elimination. This prevents accumulation of cholesterol in the _________.
LDL transports cholesterol to _________. Most cells have LDL ________ that take LDL into the cell where it releases cholesterol.
Once a cell has sufficient cholesterol a _________ _________ system inhibits the synthesis of new LDL receptors and LDL circulates in the blood where it may deposit _________ in the _________ forming atheromas.
A higher ratio of HDL to LDL will result in _________ blood cholesterol and a _________ chance of atherosclerosis.
Regular physical activity tends to raise HDL levels, dietary changes aim to _________ the levels of total fat in the diet and to replace saturated with unsaturated fats. Drugs such as _____ reduce blood cholesterol by ________ the synthesis of cholesterol by liver cells.

17. Cholesterol is synthesised by all cells, although 25% of total production takes place in the liver. A diet high in saturated fats or cholesterol causes an increase in cholesterol levels in the blood. Cholesterol is a component of cell membranes and a precursor for steroid synthesis.
HDL transports excess cholesterol from the body cells to the liver for elimination. This prevents accumulation of cholesterol in the blood.
LDL transports cholesterol to body cells. Most cells have LDL receptors that take LDL into the cell where it releases cholesterol.
Once a cell has sufficient cholesterol a negative feedback system inhibits the synthesis of new LDL receptors and LDL circulates in the blood where it may deposit cholesterol in the arteries forming atheromas.
A higher ratio of HDL to LDL will result in lower blood cholesterol and a reduced chance of atherosclerosis.
Regular physical activity tends to raise HDL levels, dietary changes aim to reduce the levels of total fat in the diet and to replace saturated with unsaturated fats. Drugs such as statins reduce blood cholesterol by inhibiting the synthesis of cholesterol by liver cells.

18. KA 7d: Learning Outcomes
State where cholesterol is synthesised
State the type of diet that can increase cholesterol levels in the blood
Give 2 reasons why cholesterol is important for cellular functions
Define HDL and LDL
Describe the role of HDL in the body
Describe the role of LDL in the body
Describe the effect of the of the negative feedback response when a cell has sufficient cholesterol levels
State what a high HDL to LDL ratio may result in
Describe 2 lifestyle choice which can improve the health of an individual
Describe the role of ‘statins’