1. What do I know? What is atherosclerosis?
What causes atherosclerosis to occur?
What effect does atherosclerosis have on arteries and blood pressure?
Which cardiovascular diseases is atherosclerosis associated with?

2. Unit 2 Physiology and Health 2. Thrombosis
Higher Human Biology
Unit 2 Physiology and Health
2. Thrombosis

3. What do I need to know? 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

4. What is thrombosis?
Thrombosis is the formation of a blood clot

5. Atheromas involvement in thrombosis
When an atheroma reaches a critical size the endothlium can rupture
Release of clotting factors that activate a cascade of reactions
Inactive enzyme prothrombin converted to active thrombin

6. Thrombus formation The diagram summarises how the thrombus forms
The enzyme thrombin converts fibrinogen to fibrin
Fibrin forms a network of fibres
The fibrin fibres form a scaffold for platelets to form clot and also for scab formation

7. Thrombus and embolus

8. Coronary – myocardial infarction
Effect of Embolus
Brain - stroke
Coronary – myocardial infarction

9. Effects of an embolus - theory
Coronary thrombosis
Brain thrombosis
Travelling embolus lodges in coronary artery
Myocardial infarction occurs – heart attack
Muscle tissue no blood supply
Deprived of oxygen
Muscle tissue dies
Travelling embolus lodges in artery of brain
Stroke occurs
Brain tissue no blood supply
Deprived of oxygen
Brain tissue dies

10. What is peripheral vascular disease?
The narrowing of the arteries due to atherosclerosis of arteries other than those of heart and brain
E.g. legs
Pain is experienced because the leg muscles are deprived of oxygen due to limited blood supply

11. Two examples Deep vein thrombosis Pulmonary embolism
Clot forms in vein commonly in leg
Caused when part of a clot/thrombus splits off and travels to lung via vena cava and pulmonary artery
Symptoms:
- chest pain
- difficulty breathing
- palpitations
Treatment: anticoagulants

12. Two examples
DVT
Pulmonary embolism

13. Activities
Testing your knowledge Qs p186 No’s 1, 2 and 4