1.10 Understand the course of events that leads to atherosclerosis (endothelial dysfunction, inflammatory response, plaque formation, raised blood pressure)
1.11 Understand the blood clotting process (thromboplastin release, conversion of
prothrombin to thrombin and fibrinogen to fibrin) and its role in cardiovascular
disease (CVD)
Atherosclerosis
- = Hardening of arteries
- Occurs when plaques (made up of a yellowish fatty substance) build up inside the arteries
- One of the causes of cardiovascular disease (CVD)
👇 You would need to know how atherosclerosis develops for IAL Edexcel Biology👇
How atherosclerosis develops
- Damage to endothelial lining of artery (e.g. high blood pressure, smoking)
- Trigger inflammatory response – white blood cells accumulate in the artery wall
- Cholesterol builds up forming a atheroma
- Calcium salts and fibers build up forming a plaque which narrows the artery
- Obstructed flow of blood lead to increased blood pressure, causing further damage to endothelial lining (positive feedback mechanism).
Blood clotting
Blood clotting is a vital defence mechanism but when a blood clot develops inside a blood vessel, can block blood flow and cause detrimental results
Steps in blood clot formation
- Stimulated by damage to blood vessel
- Blood platelets attach to the exposed collagen fibers in the blood vessel wall
- Platelets release thromboplastin, which is a clotting factor
- Thromboplastin converts prothrombin (inactive) into thrombin (active) in the presence of calcium ions and vitamin K
- Thrombin causes the conversion of soluble fibrinogen into insoluble fibrin
- The fiber forms a network of fibers which traps blood cells and debris to form a clot
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References:
1. Edexcel AS Biology Revision Guide. Edexcel.