Explain how negative feedback is used to regulate core body temperature when a person moves from a warm room into cold outdoor air.
Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).
Model answer (4 marks)
Thermoreceptors in the skin and in the hypothalamus sense a fall in body temperature below the set point.
The hypothalamus acts as the control centre and sends signals via the autonomic nervous system or hormones to the effectors.
Effectors then produce heat‑conserving or heat‑generating responses – for example vasoconstriction of skin arterioles, shivering, and contraction of the erector pili muscles (piloerection).
When the core temperature rises back to the set point the hypothalamus stops the signals, so the corrective responses cease – this is negative feedback.
The hypothalamus acts as the control centre and sends signals via the autonomic nervous system or hormones to the effectors.
Effectors then produce heat‑conserving or heat‑generating responses – for example vasoconstriction of skin arterioles, shivering, and contraction of the erector pili muscles (piloerection).
When the core temperature rises back to the set point the hypothalamus stops the signals, so the corrective responses cease – this is negative feedback.
Examiner tips
- Use the word ‘thermoreceptors’ and ‘hypothalamus’ – these are key terms. Show the sequence: detection → hypothalamus → effectors → response. Mention at least two effectors (e.g., vasoconstriction, shivering).
- Explain that the response is switched off when the set point is reached – this demonstrates negative feedback.
Common mistakes
- Omitting the hypothalamus as the control centre. Failing to mention that the response stops once the set point is reached, thus missing the negative feedback element.
Mark scheme (4 marks)
- Thermoreceptors in the skin and/or hypothalamus detect a drop in temperature below the set point.
- The hypothalamus coordinates the response by sending nerve or hormonal signals to effectors.
- Effectors produce heat-conserving or heat-generating responses, such as vasoconstriction of skin arterioles, shivering, or erector pili muscle contraction (piloerection).
- Once temperature returns to the set point, the corrective responses are switched off — this is negative feedback.
Key terms in this question
Related
- All IB DP Biology Standard Level (2023 syllabus) revision notes →
- How to answer a "Explain" question →
- Decode the mark scheme abbreviations →
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