A person goes for a run on a hot day. Explain how the body responds to maintain a constant core body temperature during this activity.

Eduqas GCSE Biology — 4.3 Homeostasis in humans · Explain · 4 marks · View as Markdown

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

Model answer (4 marks)

Body temperature rises above the set point of about 37 °C.
Thermoreceptors in the hypothalamus and skin detect the increase.
The hypothalamus signals the sweat glands to produce more sweat, which evaporates from the skin surface.
Blood vessels near the skin surface dilate (vasodilation), allowing more heat to be lost to the surroundings.

Examiner tips

  • Use the word ‘detect’ for thermoreceptors, ‘signal’ for the hypothalamus, and ‘evaporate’ for sweat; include vasodilation as a heat‑loss mechanism.
  • Show the sequence: rise in temperature → detection → sweating + vasodilation.
  • Use UK spelling and correct units (°C).

Common mistakes

  • Forgetting to mention the hypothalamus as the control centre.
  • Describing only sweating without vasodilation, or vice‑versa.
  • Using ‘heat loss’ without specifying the mechanisms (evaporation and vasodilation).

Mark scheme (4 marks)

  1. Body temperature rises above the set point / normal level (approximately 37 °C)
  2. Thermoreceptors in the hypothalamus / skin detect the rise in temperature
  3. Sweat glands produce more sweat which evaporates from the skin surface
  4. Blood vessels near the skin surface dilate (vasodilation) allowing more heat to be lost to the surroundings

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