Coronary heart disease (CHD) occurs when the coronary arteries become narrowed by a build-up of fatty deposits. Explain how a narrowing of the coronary arteries leads to a heart attack.
Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).
Coronary heart disease is one of the leading causes of death in the UK. The coronary arteries supply the heart muscle with blood. When these arteries become partially or fully blocked, the consequences for the heart can be severe.
Model answer (5 marks)
The coronary arteries supply the heart muscle with oxygenated blood and nutrients.
Fatty deposits (plaque) narrow the lumen of the coronary arteries, reducing the volume of blood that can flow through.
With less blood flow, fewer oxygen molecules (and glucose) reach the cardiac muscle cells.
The heart muscle cells cannot carry out aerobic respiration at a sufficient rate, so ATP production falls.
When the energy supply falls below the level required for contraction, the affected part of the heart muscle dies, leading to a heart attack.
Fatty deposits (plaque) narrow the lumen of the coronary arteries, reducing the volume of blood that can flow through.
With less blood flow, fewer oxygen molecules (and glucose) reach the cardiac muscle cells.
The heart muscle cells cannot carry out aerobic respiration at a sufficient rate, so ATP production falls.
When the energy supply falls below the level required for contraction, the affected part of the heart muscle dies, leading to a heart attack.
Examiner tips
- Use the exact sequence: supply → narrowing → reduced flow → less oxygen → reduced ATP → cell death. Include the term "plaque" or "fatty deposits" to show understanding. Mention that the heart muscle stops contracting to link cell death with a heart attack.
Common mistakes
- Confusing coronary arteries with systemic arteries. Failing to mention that oxygen is required for aerobic respiration. Not linking reduced ATP to loss of contraction and cell death.
Mark scheme (5 marks)
- The coronary arteries supply the heart muscle with oxygenated blood (and/or glucose/nutrients)
- Fatty deposits narrow the lumen of the coronary arteries, reducing blood flow
- Less oxygen (and/or glucose) is delivered to the heart muscle cells
- The heart muscle cells cannot carry out aerobic respiration at a sufficient rate / energy release is reduced
- The heart muscle cells die / part of the heart muscle stops contracting, causing a heart attack
Key terms in this question
coronary arteries · heart attack · fatty deposits
Related
- All Pearson Edexcel A-Level Biology A (9BI0) revision notes →
- How to answer a "Explain" question →
- Decode the mark scheme abbreviations →
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