Explain why the heart is described as a double circulatory pump.

Eduqas GCSE Biology — 1.4.2 The heart · Explain · 4 marks · View as Markdown

Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).

Model answer (4 marks)

The heart is a double circulatory pump because it moves blood through two separate circuits.
1. The right side of the heart receives de‑oxygenated blood from the body and pumps it to the lungs via the pulmonary circuit.
2. The left side receives oxygenated blood from the lungs and pumps it to the rest of the body via the systemic circuit.
3. Thus, on one complete circuit of the body, the blood passes through the heart twice – once in each circuit.
4. This arrangement allows the systemic circuit to operate at higher pressure, ensuring efficient delivery of oxygen to tissues.

Examiner tips

  • Use the phrase "double circulatory pump" early. Show the two circuits and which side of the heart pumps each. Explain the benefit of two passes – higher pressure and efficient oxygen delivery.

Common mistakes

  • Confusing the right side with oxygenated blood. Omitting the systemic circuit. Not linking the double pass to higher pressure or efficient delivery.

Mark scheme (4 marks)

  1. The heart pumps blood around two separate circuits / loops
  2. The right side of the heart pumps deoxygenated blood to the lungs (pulmonary circuit)
  3. The left side of the heart pumps oxygenated blood to the rest of the body (systemic circuit)
  4. This means blood passes through the heart twice on one complete circuit of the body / maintaining higher pressure for efficient delivery of oxygen

Key terms in this question

double circulatory pump

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