Risk Factors for Coronary Heart Disease (Edexcel IGCSE Biology): Revision Note

Heart Disease

• The coronary arteries are the blood vessels which supply cardiac muscle with oxygen and glucose

• In coronary heart disease (CHD), layers of fatty material (plaque) build up inside the coronary arteries

  • These fatty deposits are mainly formed from cholesterol

  • There are two sources of cholesterol in the body:

    • Dietary cholesterol (from animal products eaten)

    • Cholesterol synthesised by the liver

Buildup of plaque in the coronary arteries narrows the lumen

• If a coronary artery becomes partially or completely blocked by these fatty deposits, the flow of blood through the arteries is reduced, resulting in a lack of oxygen for the heart muscle

  • Partial blockage of the coronary arteries creates a restricted blood flow to the cardiac muscle cells and results in severe chest pains called angina

  • Complete blockage means cells in that area of the heart will not be able to respire aerobically, leading to a heart attack

The effect of a narrowed lumen in a coronary artery is reduced blood flow to the heart

Risk factors of coronary heart disease

• There are several risk factors which will increase the chances of coronary heart disease:

• Obesity

  • Carrying extra weight puts a strain on the heart

  • Increased weight can lead to Type 2 diabetes which further damages your blood vessels

• High blood pressure

  • This increases the force of the blood against the artery walls and consequently leads to damage of the vessels

• High cholesterol

  • Speeds up the build up of fatty plaques in the arteries leading to blockages

• Smoking

  • Chemicals in smoke cause an increase in plaque build up and an increase in blood pressure

  • Carbon monoxide also reduces the oxygen carrying capacity of the red blood cells