AQA GCSE Biology 8461: Coronary heart disease – Revision Notes

These are condensed recall notes for 4.2.2.4 Coronary heart disease: a non-communicable disease of the AQA GCSE Biology (8461) specification, Version 1.0, for teaching from September 2016 and exams from 2018 onwards. Organisation is assessed on Paper 1, set at Foundation and Higher Tier. Nothing in 4.2.2.4 is marked (HT only) or (biology only), so every line applies to both tiers. There is no required practical. The skill the specification stresses is evaluating treatments: weighing benefits against risks.

You need the heart structure and the coronary arteries from the Principles of organisation; the heart and blood vessels revision notes. Risk factors for heart disease (diet, smoking, exercise) are in the Health issues and lifestyle revision notes. The course hub is AQA GCSE Biology, and the printable checklist lists every point. To find your weak spots fast, try the free 10-minute diagnostics.

What coronary heart disease is

Coronary heart disease (CHD) is a non-communicable disease: it is not caused by a pathogen and cannot be passed from person to person.

Method in steps: the cause-and-effect chain

1. Layers of fatty material (including cholesterol) build up inside the coronary arteries.
2. The arteries narrow.
3. Less blood flows through them to the heart muscle.
4. The heart muscle gets less oxygen (and glucose).
5. Less aerobic respiration in the muscle cells, so they release less energy and can be damaged or die.

A complete blockage can cause a heart attack. Name the coronary arteries: CHD is not a blockage in the aorta or in the heart chambers.

Treating narrowed coronary arteries

Treatment	How it works	Advantages	Disadvantages
Stent	A small mesh tube placed inside the narrowed artery to hold it open	Blood flow improves straight away; the procedure is far less major than open-heart surgery; recovery is quick	Any procedure carries a risk of infection or bleeding; a blood clot can form at the stent; the artery can narrow again
Statins	Drugs that lower blood cholesterol, which slows the rate at which fatty material is deposited	No surgery; reduce the risk of heart attack and stroke; easy to take	Must be taken regularly, long term; can cause side effects (such as muscle aches); act slowly, so do not clear an existing blockage

Stents treat the narrowing that is already there. Statins reduce further build-up. They are often used together.

Faulty heart valves

Valves stop blood flowing backwards. A valve can go wrong in two ways.

Fault	Consequence
Valve does not open fully (stiff)	Less blood gets through, so the heart has to work harder
Valve leaks	Blood flows backwards, so less blood is pumped forwards with each beat

Either way, less oxygen reaches the body cells, so the person may feel tired and breathless.

Replacement valve	Advantages	Disadvantages
Biological (from animal or human tissue)	Works like a natural valve; usually no need for lifelong anti-clotting drugs	Wears out sooner, so may need replacing
Mechanical (man-made)	Very long-lasting	Patient usually needs anti-clotting drugs for life, because clots can form on it

Both need heart surgery, which carries risks.

Heart failure

When the heart can no longer pump well enough:

Treatment	Advantages	Disadvantages
Transplant of a donor heart, or heart and lungs	Can give a long-term solution	Few donors, so long waits; major surgery; risk of rejection, so immunosuppressant drugs for life
Artificial heart	Keeps a patient alive while they wait for a transplant, or lets the heart rest to aid recovery; less likely to be rejected than donor tissue	Usually a short-term measure; risk of blood clots and infection; patient depends on a power supply

Method in steps: evaluating a treatment

1. Name the treatment and say what it does.
2. Give at least one advantage (benefit).
3. Give at least one disadvantage (risk, side effect, cost, waiting time).
4. Compare with an alternative if the question gives one.
5. Finish with a justified judgement for THIS patient.

Worked reminder. A patient has one narrowed coronary artery and high cholesterol. A stent restores blood flow now; statins lower cholesterol so new fatty deposits build up more slowly. Using both treats the blockage and reduces the chance of another. The judgement depends on the patient’s fitness for a procedure and on side effects.

Must-know distinctions

• Stent vs statin: mechanical device that holds the artery open vs drug that lowers cholesterol.
• Biological vs mechanical valve: wears out sooner vs anti-clotting drugs for life.
• Donor heart vs artificial heart: long-term but rejection risk vs usually temporary.
• Coronary arteries vs aorta: the coronary arteries supply the heart muscle itself.
• Non-communicable vs communicable: CHD is not caused by a pathogen.

Quick self-test

1. Why is coronary heart disease called non-communicable?
2. Describe how fatty deposits in the coronary arteries damage the heart.
3. What is a stent, and how does it help?
4. How do statins reduce the risk of coronary heart disease?
5. Give one disadvantage of a stent and one of statins.
6. Describe the two ways a heart valve can be faulty, and one consequence of each.
7. Give one advantage and one disadvantage of a mechanical valve compared with a biological valve.
8. Give two situations in which an artificial heart might be used.
9. Give two disadvantages of a heart transplant.

Answers

1. It is not caused by a pathogen, so it cannot be passed from one person to another.
2. Fatty material builds up and narrows the arteries, so less blood flows to the heart muscle. The muscle gets less oxygen, so it respires less and can be damaged.
3. A mesh tube placed in the narrowed coronary artery. It holds the artery open so blood flow to the heart muscle improves.
4. They lower blood cholesterol, which slows the rate at which fatty material is deposited in the arteries.
5. Stent: risk of infection, a blood clot or the artery narrowing again. Statins: must be taken long term and can cause side effects.
6. It may not open fully, so less blood gets through and the heart works harder. It may leak, so blood flows backwards and less is pumped forwards.
7. Advantage: it lasts much longer. Disadvantage: the patient usually needs anti-clotting drugs for life.
8. To keep a patient alive while they wait for a transplant; to let the heart rest as an aid to recovery.
9. Any two: shortage of donors (long waits); major surgery; risk of rejection; immunosuppressant drugs for life.

Where marks are usually lost

• Writing “the arteries get blocked” without the chain: narrowed -> less blood flow -> less oxygen to the heart muscle.
• Saying statins “remove” fatty deposits. They slow the build-up.
• Saying a stent lowers cholesterol.
• Saying CHD is a blockage in the aorta or the heart chambers.
• Listing advantages only in an “evaluate” question, or ending without a judgement.
• Confusing heart valve faults (a leak or a stiff valve) with blocked arteries.

Frequently asked questions

What causes coronary heart disease? Layers of fatty material build up inside the coronary arteries, which narrow, so less blood flows to the heart muscle. The muscle gets less oxygen, so it carries out less aerobic respiration.

What is the difference between a stent and a statin? A stent is a mechanical device that holds a narrowed artery open. A statin is a drug that reduces blood cholesterol, slowing the build-up of fatty material.

What can go wrong with heart valves? A valve can leak or become stiff and fail to open fully. Faulty valves can be replaced with biological or mechanical valves.

Is coronary heart disease communicable? No. Coronary heart disease is a non-communicable disease; it is not caused by a pathogen and cannot spread between people.

How do you answer an “evaluate” question on CHD treatments? Say what the treatment does, give at least one advantage and one disadvantage, compare with an alternative if given, and finish with a justified judgement for that patient.

Official syllabus

AQA GCSE Biology (8461) specification, Version 1.0, for teaching from September 2016 and exams from 2018 onwards (AQA), section 4.2 Organisation: 4.2.2.4 Coronary heart disease: a non-communicable disease.