Coronary Heart Disease
Master Coronary Heart Disease for GCSE Biology with this free worksheet and full mark scheme — Foundation and Higher exam-style questions with worked answers for AQA, Edexcel and OCR. Understand how fatty deposits narrow the coronary arteries, and be ready to evaluate treatments such as stents and statins.
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Topic overview
Coronary heart disease occurs when layers of fatty material build up inside the coronary arteries, narrowing them.
The coronary arteries supply the heart muscle itself with blood. When they narrow, blood flow is reduced, so less oxygen reaches the heart muscle and less energy is released by respiration. If an artery becomes blocked completely, part of the heart muscle dies, causing a heart attack.
Treatments include stents, which are inserted to hold the artery open, and statins, which are drugs that reduce blood cholesterol and so slow the rate of fatty deposit formation. Each has advantages and drawbacks, and questions often ask you to evaluate rather than simply describe.
Revision notes
The cause
Fatty material builds up in the coronary arteries, narrowing the lumen and reducing blood flow to the heart muscle.
Less blood means less oxygen and glucose reaching the muscle, so less energy is released by respiration. Complete blockage causes a heart attack.
Stents
A stent is a mesh tube inserted into the artery to hold it open, restoring blood flow.
Advantages: effective for a long time, and recovery from surgery is relatively quick. Drawbacks: the risk of complications during surgery, and the risk of a blood clot forming near the stent.
Statins
Statins reduce the amount of low-density cholesterol in the blood, slowing the rate at which fatty material is deposited.
Advantages: they reduce heart attacks and strokes, and may increase beneficial cholesterol. Drawbacks: they must be taken long-term, can have side effects such as muscle pain, and their effect is not immediate.
Key points
- Coronary arteries supply the heart muscle with blood.
- Fatty deposits narrow them, reducing blood flow.
- Less oxygen means less energy released by respiration.
- Stents hold the artery open.
- Statins reduce blood cholesterol.
- Both treatments have advantages and drawbacks.
Worked examples
Example 1
Explain why narrowing of the coronary arteries reduces the function of the heart. [3 marks]
Model answer
Narrowed arteries reduce blood flow to the heart muscle (1 mark), so less oxygen reaches the muscle cells (1 mark). This means less energy is released by respiration, so the heart cannot contract as effectively (1 mark).
Example 2
Give one advantage and one disadvantage of using a stent. [2 marks]
Model answer
Advantage: it holds the artery open so blood flow to the heart muscle is restored, and the effect lasts a long time (1 mark). Disadvantage: there is a risk of complications during the operation, or of a blood clot forming near the stent (1 mark).
Example 3
Explain how statins reduce the risk of a heart attack. [2 marks]
Model answer
Statins reduce the level of cholesterol in the blood (1 mark), which slows the rate at which fatty material is deposited in the coronary arteries, so they are less likely to become blocked (1 mark).
Common mistakes
Saying coronary arteries carry blood to the body.
They supply the heart muscle itself. The aorta carries blood to the body.
Saying statins unblock arteries.
They slow further deposits by lowering cholesterol; they do not remove existing blockages.
Giving only advantages when asked to evaluate.
Evaluation questions need both sides and usually a judgement.
Forgetting to link reduced oxygen to reduced energy.
That chain of reasoning is usually where the marks are.
Exam tips
- Follow the chain: narrowed artery, less blood, less oxygen, less energy.
- Give both an advantage and a disadvantage when evaluating a treatment.
- Be precise that statins slow deposits rather than removing them.
- Name the coronary arteries specifically.
Key terms
- Coronary artery
- An artery supplying blood to the heart muscle.
- Stent
- A mesh tube inserted to hold an artery open.
- Statin
- A drug that lowers blood cholesterol.
- Cholesterol
- A fatty substance that can build up in artery walls.
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Written and reviewed against the current AQA, Edexcel and OCR specifications. Spotted an error? Let us know.