Coronary Heart Disease A Non-Communicable Disease — AQA GCSE Biology

SPEC 4.2.2.4–4.2.2.7 • ORGANISATION — DISEASE

CHD, Health & Cancer

When the circulatory system goes wrong — coronary heart disease, the three named treatments, health and disease interactions, and benign vs malignant tumours.

The Stent Trap

A reliable 2-mark question on Paper 1 asks you to explain how a stent treats coronary heart disease. Most students know what a stent is — and still lose marks.

AQA mark schemes need two distinct points: the stent opens / widens / keeps open the blocked vessel, AND this allows more blood / oxygen / glucose to reach the heart muscle. "The stent helps the heart" scores zero. — pattern recurring across AQA CHD questions

What You Get From This Lesson

CHD with its three named treatments (and the exact mark-scheme wording), the definition of health and how diseases interact, and the difference between benign and malignant tumours — with the "secondary tumours" phrase you can't skip.

What You'll Learn

By the end of this lesson, you'll be able to:

Lesson Objectives

Describe coronary heart disease and explain how each of the three named treatments works (stents, statins, faulty valve replacement).

Define health and explain the difference between communicable and non-communicable diseases, plus how they can interact.

Distinguish benign from malignant tumours using mark-scheme wording (especially "secondary tumours"), and name the major risk factors for cancer.

Spec ref: 4.2.2.4 (CHD), 4.2.2.5 (Health), 4.2.2.6 (Lifestyle), 4.2.2.7 (Cancer). Paper 1, Higher tier.

Coronary Heart Disease (CHD)

The coronary arteries supply the heart muscle with oxygenated blood. In CHD, those arteries get narrowed by fatty deposits.

Mechanism (memorise the sequence)

Layers of fatty material build up inside the coronary arteries.

This narrows the arteries, reducing blood flow.

Less oxygen (and glucose) reaches the heart muscle cells.

Heart muscle cells respire less → release less energy → can lead to heart attack if the artery becomes completely blocked.

Naming Alert

Be specific: it's the coronary arteries that narrow — not "arteries in the heart" or just "blood vessels". Naming the right vessel often carries a mark.

Three Named Treatments

The spec names three treatments you must know. Each one comes with pros and cons — exam questions often ask you to evaluate, meaning give both sides.

Stents

A wire mesh tube fitted inside the artery to physically open / widen the narrowed vessel.

Statins

Drugs that lower blood cholesterol, slowing fatty material buildup.

Valve replacement

Replacing leaky or stiff heart valves with biological (animal) or mechanical valves.

Memory Trick

The three treatments target different problems: stents fix a narrowed artery directly; statins slow the underlying cholesterol buildup; valve replacement fixes a different heart problem (faulty valves, not narrowing).

Stents

A stent is a wire mesh tube inserted into a narrowed coronary artery. It physically holds the vessel open, restoring blood flow to the heart muscle.

✓ Pros

Effective at restoring blood flow long-term.

Relatively quick procedure compared to open-heart surgery.

Reduces risk of heart attack.

✗ Cons

Surgical risk during fitting.

Risk of blood clot forming near the stent.

The artery can re-narrow over time.

Mark-Scheme Wording

For "how a stent works" — use "opens / widens / keeps open". AQA mark schemes explicitly do NOT credit "unblocks" (a stent doesn't remove the fatty material; it just pushes the artery open). Pair this with "allows more blood / oxygen / glucose to reach the heart muscle" for the second mark.

Statins

Statins are drugs taken regularly that lower blood cholesterol levels. Lower cholesterol → slower fatty material deposition in arteries → reduced risk of CHD developing further.

✓ Pros

Reduce risk of heart attack and stroke.

Widely available; cheap; non-surgical.

✗ Cons

Must be taken for life .

Possible side effects (muscle pain, liver damage).

Take time to be effective — not for emergencies.

CRITICAL — Use The Term "Statins"

AQA mark schemes require the exact spec term: "statins". Common wrong answers that score ZERO:

"Anti-cholesterol drug" — this is a description, not the named term.

"Blood thinners" — these are different drugs (anticoagulants, e.g. warfarin).

"Insulin" — this is for diabetes.

Memorise the word statins verbatim.

Faulty Heart Valves

Some people develop problems with their heart valves — these are separate from CHD but also part of the spec for cardiovascular treatments.

Two Types of Valve Problem

Leaky valve — doesn't close properly, so blood flows backwards (regurgitation).

Stiff valve — doesn't open fully, so blood flow is restricted.

Either way, the heart has to work harder, and less blood gets to where it needs to go.

ReplacementProsCons

Biological valve (from a pig, cow, or human donor)No need for lifelong anticoagulant drugs; lower risk of blood clots.Wears out faster than mechanical — may need replacing again.

Mechanical valve (man-made)Very long-lasting / durable.Requires lifelong anticoagulants to prevent blood clots.

When The Whole Heart Fails

If the heart can no longer pump effectively — called heart failure — more drastic options are needed.

Heart Transplant

A diseased heart is replaced with a healthy donor heart (from a recently deceased person). Sometimes lungs are transplanted too.

✓ Pros

Cures heart failure — gives a normal-functioning heart back.

✗ Cons

Donor shortage; risk of rejection (patient needs immunosuppressants); major surgery.

Artificial Heart

A man-made pump used temporarily:

To keep a patient alive while waiting for a donor heart.

To allow the natural heart to rest and recover .

✓ Pros

No rejection issue (not biological tissue).

✗ Cons

Not a permanent fix; blood clots can form on the mechanical surface.

Health vs Disease

Before risk factors, get the definitions right. Mark schemes are precise about both.

Spec definitions

Health is the state of physical and mental wellbeing — not just the absence of disease.

Disease is a major cause of ill health. Two categories:

Communicable

Caused by pathogens (bacteria, viruses, fungi, protists). Can spread from one organism to another.

Examples: measles, salmonella, athlete's foot. Covered in detail in Module 3.

Non-communicable

Cannot be passed from one organism to another. Often linked to lifestyle, age, or genetics.

Examples: CHD, type 2 diabetes, most cancers, asthma.

Other Factors

The spec also lists diet, stress, and life situations as factors affecting both physical and mental health — not just whether someone has a "disease".

Diseases Interact

A specific spec point — different types of disease can trigger or worsen each other. Four examples to know:

Immune system defect→ more likely to suffer from infectious diseases (e.g. HIV reduces immunity → opportunistic infections).

Viruses living in cells→ can trigger cancers (e.g. HPV → cervical cancer).

Immune reactions to a pathogen→ can trigger allergies such as skin rashes and asthma.

Severe physical ill health→ can lead to depression and other mental illness.

Why This Matters

Exam questions sometimes give a scenario (e.g. "a person with HIV develops tuberculosis") and ask you to explain the link. The link is usually one of the four interactions above.

Risk Factors

A risk factor is an aspect of lifestyle, or a substance in the body or environment, linked to an increased rate of a disease. The spec lists these specific links — learn them as written:

Risk / lifestyle factorDisease(s) it's linked to

Diet, smoking and lack of exerciseCardiovascular disease (incl. CHD)

ObesityType 2 diabetes (spec-specific link)

AlcoholThe liver and brain function

SmokingLung disease AND lung cancer

Smoking AND alcohol (during pregnancy)Effects on unborn babies

Carcinogens , including ionising radiationCancer

Spec note: diseases interact

Many diseases are caused by the interaction of a number of factors — not just one. A person's risk depends on genes, lifestyle, environment, and other diseases all combining. Non-communicable diseases also have major human and financial costs at individual, local, national, and global levels.

Obesity Trap — "Lifestyle factor" ≠ "Risk factor"

AQA mark schemes flag this regularly. Obesity is a RISK FACTOR for Type 2 diabetes (per spec), but NOT a "lifestyle factor". If a question asks for a lifestyle factor that increases disease risk, write "poor diet" or "lack of exercise" — NOT "obesity". Obesity is the outcome of those lifestyle factors.

Causation vs Correlation

A causal mechanism has been proven for some risk factors (e.g. smoking → tar damages cilia → mutations → lung cancer). For others, only a correlation is shown — the link is statistical, not necessarily causal. Mark schemes distinguish these.

Cancer: Benign vs Malignant

Cancer is caused by changes in cells that lead to uncontrolled growth and division. The spec wants you to distinguish two tumour types.

Benign Tumours

Growths of abnormal cells contained in one area .

Usually within a membrane .

Do NOT spread to other parts of the body.

Generally not life-threatening.

Malignant Tumours (Cancers)

Invade neighbouring tissues.

Cells spread in the blood to other parts of the body.

Form secondary tumours elsewhere.

Life-threatening.

Mark-Scheme Phrase

For malignant tumours, the credit-worthy phrase is "forms secondary tumours" — not just "spreads" or "moves around". The full phrase: "malignant tumour cells spread in the blood to form secondary tumours".

Cancer Risk Factors

The spec lists three categories of risk factor for cancer:

Genetic

Some people inherit faulty genes that increase their risk. Example: BRCA1/BRCA2 mutations increase breast cancer risk.

Lifestyle

Smoking → lung cancer (carcinogens in tar)

UV exposure → skin cancer

Alcohol → liver cancer

Diet → various cancers (some links)

Carcinogens

Substances or radiation that cause cancer. Includes ionising radiation (X-rays, UV, gamma rays) and chemicals (e.g. in tobacco smoke, asbestos).

PEE Tip

When asked "explain why smoking causes lung cancer" — the answer needs a causal chain: tobacco smoke contains carcinogens → damages DNA in lung cells → mutations → uncontrolled cell division → malignant tumour.

Worked Example

A doctor recommends fitting a stent for a patient with coronary heart disease. Explain how the stent helps to treat the disease.2 marks

POINT

Two distinct effects of the stent — physical action on the artery, plus consequence for the heart muscle.

EVIDENCE

The stent is a wire mesh that opens / widens the narrowed coronary artery (mark-scheme wording — not "unblocks").

EXPLAIN

Model answer: "The stent opens (widens) the narrowed coronary artery. This allows more blood (carrying oxygen and glucose) to flow to the heart muscle, so the heart muscle can carry out aerobic respiration to release the energy needed to contract." ✓✓

Mark 1: "opens / widens / keeps open" the vessel. Mark 2: "allows more blood / oxygen / glucose" to reach the heart muscle. Vague phrases like "helps the heart" or "unblocks the vessel" score zero. Be specific, and link the action to the consequence.

Three Examiner Alerts

Alert 1 — Stents "open / widen", not "unblock"

For stent questions, the credit-worthy phrase is "opens / widens / keeps open". AQA mark schemes explicitly reject "unblocks the vessel" — a stent doesn't remove the fatty material, it just holds the vessel open.

Alert 2 — "Statins" verbatim

Memorise the exact spec term: statins. AQA examiner reports consistently flag students writing "anti-cholesterol drugs" (a description, not the term), "blood thinners" (wrong drug class), or "insulin" (for diabetes) — all score zero.

Alert 3 — Malignant tumours form "secondary tumours"

When distinguishing benign from malignant, the mark-scheme phrase for malignant is "spreads (in the blood) to form secondary tumours". Just saying "spreads" is often not enough — the phrase "secondary tumours" is what locks in the mark.

Common Errors — Wrong vs Right

Wrong

"Stent unblocks the vessel."

Right

"Stent opens / widens / keeps open the vessel."

Wrong

"Statins thin the blood."

Right

"Statins lower blood cholesterol, slowing fatty buildup."

Wrong

"All tumours spread to other parts of the body."

Right

"Benign tumours stay in one area; malignant tumours spread in the blood to form secondary tumours."

Wrong

"Non-communicable diseases are caused by germs."

Right

"Non-communicable diseases are not caused by pathogens — risk factors include diet, smoking, alcohol."

Wrong

"Obesity is a lifestyle factor."

Right

"Obesity is a risk factor for type 2 diabetes. The lifestyle factors are poor diet and lack of exercise."

Wrong

"CHD blocks the heart."

Right

"CHD narrows the coronary arteries, reducing blood flow to the heart muscle."

Three Things To Remember

1. CHD & Three Named Treatments

Coronary heart disease = fatty material narrows the coronary arteries. Three treatments: stents (open/widen the vessel), statins (lower blood cholesterol), faulty valve replacement (biological or mechanical). Heart transplants and artificial hearts for heart failure.

2. Health & Risk Factors

Health = state of physical AND mental wellbeing. Diseases are communicable (pathogens, spread) or non-communicable (lifestyle/genetics, don't spread). Spec-named factors: diet/smoking/exercise → cardiovascular disease; obesity → type 2 diabetes; alcohol → liver and brain function; smoking → lung disease/cancer; smoking & alcohol → unborn babies; carcinogens (incl. ionising radiation) → cancer. Diseases interact (viruses → cancers; immune defects → infections).

3. Cancer — Benign vs Malignant

Cancer = uncontrolled cell division. Benign tumours stay in one area within a membrane — don't spread. Malignant tumours invade neighbouring tissues and spread in the blood to form secondary tumours. Risk factors: genetic, lifestyle, carcinogens (incl. ionising radiation).

Next Lesson

Lesson 2.08 — Plant Tissues, Transpiration & Translocation. Switching from animals to plants: leaf structure, xylem & phloem, how water moves up a plant, and what guard cells actually do.