1. Cardiovascular Disease
Physiology and Health
Higher Human Biology
Subtopic 15 (b)
Cardiovascular Disease
Cholesterol

2. Learning Intentions
To explain the role of LDL and HDL in controlling cholesterol
To describe how to lower blood cholesterol levels and how to screen for familial hypercholerterolaemia

3. Cholesterol Cholesterol is a type of lipid It’s important because :
1. it’s a precursor for steroids
2. it’s part of the cell membrane
It’s produced in liver cells from saturated fats in your diet

5. Lipoproteins Molecules that contain lipid and protein.
Present in the blood
Help transport lipids about the body

6. LDLs Low density lipoproteins Produced in the liver
Help transport cholesterol
Transports about 60-70% of blood cholesterol

7. Cells make LDL receptors and insert them in the cell membrane
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Cells make LDL receptors and insert them in the cell membrane
LDL-cholesterol molecule attaches and is taken into the cell for use

8. Negative Feedback
Cholesterol levels are controlled by negative feedback:
Cell has adequate supply of cholesterol
LDL receptor synthesis is inhibited
Less LDL-cholesterol is absorbed
But…….
4. LDL-Cholesterol is taken up by endothelial cells lining an artery
5. Cholesterol is deposited in an atheroma in the wall of the artery……..
….. ATHEROSCLEROSIS

9. HDLs High density lipoproteins
Help transport excess cholesterol from body cells to the liver to eliminate excess
Not taken into artery walls
Transports about 20-30% of blood cholesterol

10. HDL and LDL

11. LDL
liver
cells
HDL

12. HDL and LDL Balance Higher HDL – LDL Higher LDL – HDL
= lower blood cholesterol
Higher LDL – HDL
= higher blood cholesterol
= higher chance of CVD
Statins are drugs that can inhibit cholesterol synthesis and lower blood cholesterol levels.

13. Staying Healthy
HDL levels can be raised by replacing saturated fat with unsaturated fat and consuming less fat overall.
Regular physical exercise raises HDL levels and lowers the risk of CVD.

14. Familial Hypercholesterolaemia
Inherited – autosomal dominant
Gene mutation causes a decrease / structural change in LDL receptors in cell membranes
LDL cholesterol can’t unload cholesterol to the cells so it stays in the blood.
Younger sufferers may suffer CVD if untreated.

15. Page 188

16. Screening and Treatment
Genetic screening can be used to test for FH.
Modified lifestyles and taking medication such as statins can help.

17. Learning Intentions
To explain the role of LDL and HDL in controlling cholesterol
To describe how to lower blood cholesterol levels and how to screen for familial hypercholerterolaemia