What do I remember? What is thrombosis? What effect does a ruptured atheroma have on thrombus formation? What are the roles of thrombin, fibrinogen and fibrin in thrombus formation? How is a thrombus different to an embolus? What effect does a thrombosis have on the heart and brain? What is peripheral vascular disease? Describe two examples of peripheral vascular disease

Higher Human Biology Unit 2 Physiology and Health 3. Cholesterol and Familial cholesterolaemia

What do I need to know? What is cholesterol? Where is cholesterol formed? What is the function of cholesterol? What causes an increase in blood cholesterol? What’s the difference between HDL and LDL? What is the role of LDL in atheroma formation? What ratio of HDL to LDL is beneficial? How can cholesterol levels be reduced? What is familial cholesterolaemia and what is its effect? How is familial cholesterolaemia treated?

What is cholesterol? Cholesterol is a sterol due to hydroxyl group and its steroid rings Part of family of compounds called lipids Lipids are simple fats (saturated/unsaturated) and more complex steroids

Synthesis of cholesterol Formed in all cells 25% of all cholesterol in body synthesised in liver from saturated fats gained from diet

Function of cholesterol Synthesis of steroids Cell membrane Major component of cell Without cholesterol membranes would be too fluid and too permeable to some substances membranes Important in formation of steroids It is a precursor molecule for many substances E.g. steroid hormones E.g. oestrogen and progesterone

What causes an increase in cholesterol? A diet high in saturated fat causes an accumulation of cholesterol in the blood A condition called familial hypercholesterolaemia also raises cholesterol levels

The difference between LDL and HDL? Low density lipoproteins Transports cholesterol to body cells Most cells synthesise and insert LDL receptors in their plasma membranes LDL-cholesterol binds to receptor LDL-cholesterol engulfed by cell Cholesterol released for use

Difference between LDL and HDL cont’d If too much cholesterol: negative feedback occurs Synthesis of LDL receptors inhibited Less receptors less cholesterol taken up by body cells More cholesterol in blood Endothelial cells of arteries absorb some cholesterol Leads to atheroma

High density lipoprotein HDL High density lipoprotein Transports excess cholesterol from body cells to liver for elimination Prevents accumulation of cholesterol in the blood HDL-cholesterol not absorbed by arterial walls Does not contribute to atherosclerosis Higher ratio of HDL:LDL decreases blood cholesterol and reduces risk of cardiovascular disease

How can cholesterol levels be reduced? Statins – inhibit synthesis of cholesterol in liver

What is familial hypercholesterolaemia? Revision!! What is meant by autosomal? What is meant by dominant? FH is an autosomal dominant disorder Individuals predisposed to high cholesterol Number of LDL receptors reduced/altered

How is familial hypercholesterolaemia treated? Genetic testing can confirm diagnosis Lifestyle modifications E.g.? Medication Treatment designed to prevent early accumulation of cholesterol and increased risk of cardiovascular disease

What do I know? What is cholesterol? Where is cholesterol formed? What is the function of cholesterol? What causes an increase in blood cholesterol? What’s the difference between HDL and LDL? What is the role of LDL in atheroma formation? What ratio of HDL to LDL is beneficial? How can cholesterol levels be reduced? What is familial cholesterolaemia and what is its effect? How is familial cholesterolaemia treated?

Activities Testing your knowledge Qs p186 No. 3