Explain how the body responds to prevent the core body temperature from falling too low when a person is exposed to cold conditions.

WJEC GCSE Biology (Wales) — 2.5.3 Homeostasis · Explain · 4 marks · View as Markdown

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

Model answer (4 marks)

Thermoreceptors in the skin and the hypothalamus detect a fall in core temperature.
The hypothalamus triggers shivering – rapid, involuntary muscle contractions that generate heat.
It also causes vasoconstriction of blood vessels close to the skin, reducing heat loss.
Erector pili muscles contract, making hairs stand up and trapping an insulating layer of air.

Examiner tips

  • Use the exact terms: thermoreceptors, hypothalamus, shivering, vasoconstriction, erector pili muscles.
  • Show the cause–effect chain: detection → response → effect on heat loss.
  • Keep each point short and separate, matching the four mark points.

Common mistakes

  • Mixing up vasoconstriction with vasodilation; forgetting to mention the hypothalamus; describing hair standing as a separate response rather than part of the heat‑retention mechanism.

Mark scheme (4 marks)

  1. Thermoreceptors in the skin / hypothalamus detect a fall in body temperature
  2. Muscles shiver / rapid muscle contractions occur, releasing heat energy
  3. Blood vessels near the skin surface constrict / vasoconstriction occurs, reducing heat loss
  4. Hairs on the skin stand up / erector muscles contract, trapping an insulating layer of air

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