9.1.5B5. Transport in Humans

Coronary Heart Disease — Combined Science 0653 - Biology Revision Notes & Topical Questions

5 min read 6 parts Lesson 9 of 15 Unit quiz

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Part 1 of 4The heart needs its own blood supply

Cardiac muscle

Cardiac muscle The wall of the heart is made of muscle that contracts non-stop throughout life, so its cells respire constantly.
Blood inside the chambers cannot supply these cells quickly enough, so the muscle has its own blood vessels.

Coronary arteries

Coronary arteries The coronary arteries branch from the aorta and run over the surface of the heart.
They deliver oxygen and glucose to the muscle cells and carry away carbon dioxide and other wastes.

1Fatty deposits form

Fatty deposits form Cholesterol and other fatty material build up in the artery wall as plaques.

2The artery narrows

The artery narrows The lumen gets smaller and the wall becomes stiff, so it cannot stretch properly as blood is forced through.

3Blood flow is reduced

Blood flow is reduced Less oxygen and glucose reach the heart muscle, so less aerobic respiration can take place.

4Symptoms appear

Symptoms appear Partial blockage can cause severe chest pain known as angina, especially during exertion.

5Complete blockage

Complete blockage If a coronary artery is completely blocked, the muscle cells it supplies cannot respire or contract.
- This is a heart attack.

Risk factor	How it raises the risk
Diet high in saturated fat	Raises blood cholesterol, so more plaque forms in the arteries.
Smoking	Chemicals damage artery walls and raise blood pressure, and carbon monoxide reduces the oxygen carried by the blood.
Lack of exercise	Contributes to weight gain, high blood pressure and higher cholesterol.
High blood pressure	Puts extra strain on artery walls and encourages damage and plaque formation.
Stress	Can raise blood pressure and may lead to unhealthy habits such as smoking and poor diet.
Genetic inheritance and age	Some people inherit a tendency to high cholesterol, and risk rises with age; these cannot be changed.

Lower the chance of CHD

Stop smoking

Stop smoking Removes the damage to artery walls and allows the blood to carry more oxygen.

Healthier diet

Healthier diet Eat less animal fat and more fruit and vegetables to reduce blood cholesterol and help control body mass.

Regular exercise

Regular exercise Helps with weight loss, lowers blood pressure and cholesterol and can reduce stress.

Manage stress

Manage stress Relaxation, enough sleep and a balanced lifestyle help blood pressure stay lower.

Term	Meaning
Coronary artery	A blood vessel that supplies the heart muscle itself with oxygenated blood.
Plaque	A fatty deposit, mainly cholesterol, that builds up inside the wall of an artery.
Angina	Severe chest pain caused by a restricted blood flow to part of the heart muscle.
Heart attack	Death of part of the heart muscle after its blood supply is completely blocked.
Cholesterol	A fatty substance in the blood that can be deposited in artery walls.
Risk factor	Something that increases the chance of developing a disease.

Saying that the heart is supplied by the blood inside its chambers. The muscle is supplied by the coronary arteries.

Confusing the coronary arteries with the pulmonary artery or the aorta, which are different vessels.

Stating that a risk factor definitely causes the disease. It only increases the chance of getting it.

Writing that angina and a heart attack are the same. Angina is pain from reduced flow; a heart attack follows complete blockage.

Forgetting to link blocked arteries to less oxygen for respiration in the muscle cells.

Last updated: 20 October 2026