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1.2.5Unit 1: Lifestyle, Transport, Genes and Health

Atherosclerosis — IAL Edexcel Linear Revision Notes & Topical Questions

5 min read 4 parts Lesson 17 of 29 Unit quiz

📚 IAL Edexcel Linear Hub / Topical Revision
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Part 1 of 4Development of an Atheroma

1.2.5 Atherosclerosis
1
The endothelium lining an artery is damaged, for example by high blood pressure, smoking or high levels of low-density lipoproteins.
2
An inflammatory response follows and white blood cells, mainly macrophages, move into the damaged wall and take up cholesterol.
3
Fatty deposits build up beneath the endothelium, forming fatty streaks, which are an early sign of the disease.
4
Cholesterol, dead cells, fibrous tissue and calcium salts accumulate to form a hard plaque called an atheroma.
5
The atheroma narrows the lumen and the artery loses elasticity, so blood pressure rises and flow is reduced.

Part 2 of 4Consequences

Rupture and thrombosis
  • If the atheroma ruptures, the damaged lining triggers the clotting cascade and a thrombus forms, which can block the artery.
Aneurysm
  • A weakened artery wall can swell and bulge outwards under pressure, forming an aneurysm that may burst, causing severe internal bleeding.
Coronary heart disease
  • Narrowed coronary arteries deliver less oxygen to heart muscle, which can cause chest pain known as angina.
Myocardial infarction
  • Complete blockage of a coronary artery starves part of the heart muscle of oxygen so the cells die, which is a heart attack.
Stroke
  • A blockage or bleed in an artery supplying the brain cuts off oxygen to part of the brain and leads to a stroke.

Part 3 of 4Risk Factors

Risk Factors
High blood pressure
  • Raised pressure damages the endothelium more readily, which starts the process of atheroma formation.
Smoking
  • Chemicals in tobacco smoke damage the endothelium and carbon monoxide reduces oxygen carried by the blood.
Diet
  • High intake of saturated fat and salt raises blood cholesterol and blood pressure respectively.
Other factors
  • Age, genetics, lack of exercise, obesity and diabetes all increase the likelihood of developing atherosclerosis.

Part 4 of 4Exam Checklist & Tips

1.2.5 – Key Points for the Exam

  • Atherosclerosis The disease in which atheromas form in the walls of arteries.
  • Atheroma A plaque of cholesterol, cells and fibrous tissue in an artery wall.
  • Thrombus A blood clot that forms inside a blood vessel.
  • Aneurysm A swelling of a weakened artery wall.
  • Myocardial infarction Death of heart muscle caused by a blocked coronary artery.

Common Mistakes

  • Describing platelets as red blood cell fragments; they are cell fragments from larger bone marrow cells.
  • Saying that the atheroma forms on the outer surface of the artery rather than beneath the endothelium.
  • Stating that atherosclerosis only affects coronary arteries; any artery can be affected.
  • Using the terms thrombus and atheroma interchangeably, although a thrombus is a clot and an atheroma is a plaque.

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