A person moves from a warm room into very cold outdoor conditions. Explain how the body responds to maintain a stable core body temperature.
Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).
When the body detects a drop in skin and core temperature, several physiological responses are triggered to reduce heat loss and increase heat production.
Model answer (5 marks)
Thermoreceptors in the skin and the hypothalamus detect the fall in skin and core temperature.
Vasoconstriction of the cutaneous blood vessels occurs, narrowing the vessels and reducing blood flow to the skin.
This limits heat loss by decreasing radiation and convection from the skin surface.
Shivering is triggered; skeletal muscles contract rapidly and involuntarily, producing heat.
All these responses are part of a negative‑feedback system that restores and maintains normal core temperature.
Vasoconstriction of the cutaneous blood vessels occurs, narrowing the vessels and reducing blood flow to the skin.
This limits heat loss by decreasing radiation and convection from the skin surface.
Shivering is triggered; skeletal muscles contract rapidly and involuntarily, producing heat.
All these responses are part of a negative‑feedback system that restores and maintains normal core temperature.
Examiner tips
- Use the exact terminology: thermoreceptors, vasoconstriction, shivering, negative feedback.
- Show the sequence: detection → vasoconstriction → reduced heat loss → shivering → temperature restored.
- Mention the role of the hypothalamus as the control centre.
Common mistakes
- Confusing vasodilation with vasoconstriction; describing increased heat loss.
- Failing to mention the hypothalamus or negative feedback loop.
- Using vague terms like ‘body reacts’ instead of specific responses.
Mark scheme (5 marks)
- Thermoreceptors in the skin / hypothalamus detect the drop in temperature
- Vasoconstriction occurs — blood vessels supplying the skin surface constrict / narrow
- Vasoconstriction reduces heat loss from the skin (by reducing radiation / convection from the surface)
- Shivering occurs — skeletal muscles contract rapidly / involuntarily
- These responses are coordinated by negative feedback to restore / maintain normal core body temperature
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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