Coronary Heart Disease (Cambridge O Level Biology)

• The heart is made of muscle cells that need their own supply of blood to deliver oxygen, glucose and other nutrients and remove carbon dioxide and other waste products
• The blood is supplied by the coronary arteries
• A coronary artery can become partially or completely blocked by fatty deposits called ‘plaques’ (mainly formed from saturated fat and cholesterol)
  • The coronary arteries lose elasticity, meaning they cannot stretch to accommodate the blood which is being forced through them; this leads to coronary heart disease, or CHD
• 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 and can no longer contract, leading to a heart attack

Plaque can build up in the coronary arteries, reducing the supply of blood to the heart muscle

The effect of CHD on the coronary arteries diagram

CHD can lead to a heart attack

Risk factors for CHD table

Factor	Explanation
Poor diet	Eating more saturated fat increases cholesterol levels, increasing the chance of the buildup of fatty plaques.
Stress	When under stress, hormones produced can increase blood pressure, increasing the chance of a blockage in the coronary arteries.
Smoking	Nicotine in cigarettes will cause blood vessels to become narrower, increasing blood pressure which will cause the buildup of fat globules. If this occurs in the coronary artery, this will cause coronary heart disease.
Genetic predisposition	Studies show that people with a family history of coronary heart disease are more likely to develop it themselves, suggesting it partly has a genetic basis.
Age	The risk of developing coronary heart disease increases as a person gets older.
Gender	Males are more likely to develop coronary heart disease than females.

Reducing the risks of developing coronary heart disease

• Quit smoking
• Diet - reduce animal fats and eat more fruits and vegetables - this will reduce cholesterol levels in the blood and help with weight loss if overweight
• Exercise regularly - again, this will help with weight loss, decrease blood pressure and cholesterol levels and help reduce stress