# A runner completes a long-distance race on a hot day. During the race, the runner's core body temperature rises above the normal set point. Explain how the body responds to return the core body temperature to the set point.

> Pearson Edexcel A-Level Biology A (9BI0) — Topic 6 Response to Change · Explain · 5 marks

> During intense exercise, muscles generate large amounts of thermal energy. The nervous system detects changes in body temperature and coordinates responses to restore normal conditions.

## Mark scheme (5 marks)

1. Thermoreceptors in the hypothalamus detect the rise in core body temperature above the set point
2. Vasodilation occurs — blood vessels (arterioles) near the skin surface widen / dilate
3. More blood flows to the skin surface, so more thermal energy is transferred to the environment / lost by radiation
4. Sweat glands produce / release more sweat onto the skin surface
5. Sweat evaporates from the skin surface, which transfers thermal energy away from the body / cools the body

## Key terms

- [set point](https://www.gradenine.co.uk/glossary/set-point)

## Related

- [Revision notes for Pearson Edexcel A-Level Biology A (9BI0)](https://www.gradenine.co.uk/learn)
- [How to answer "Explain" questions](https://www.gradenine.co.uk/tools/command-word-cheatsheet)
- [Practice this with AI marking (free)](https://www.gradenine.co.uk/start)

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Source: [GradeNine](https://www.gradenine.co.uk/q/a-runner-completes-a-long-distance-race-19dc218e) · Published by Druglandscape Ltd.