# A person goes for a long run on a hot day. During the run, their body temperature rises above the normal set point. Explain how the body responds to return body temperature to normal.

> Edexcel A-Level Biology A: Salters-Nuffield (9BN0) — 4.6 Homeostasis · Explain · 5 marks

> During exercise, muscles release large amounts of heat energy as a by-product of increased respiration. The body must maintain a constant internal temperature of approximately 37 °C.

## Mark scheme (5 marks)

1. Thermoreceptors / receptors in the skin and/or hypothalamus detect the rise in body temperature above the set point
2. A signal / nervous impulse is sent from the hypothalamus to effectors in the skin
3. Sweat glands produce more sweat, which evaporates from the skin surface, removing heat energy
4. Vasodilation occurs — blood vessels near the skin surface widen, increasing blood flow to the skin so more heat is lost to the surroundings
5. This is an example of negative feedback — the response reduces the change and returns body temperature back to the set point / normal level

## Key terms

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

## Related

- [Revision notes for Edexcel A-Level Biology A: Salters-Nuffield (9BN0)](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-person-goes-for-a-long-7cb215ae) · Published by Druglandscape Ltd.