# A student touches a hot surface and quickly pulls their hand away before feeling pain. Explain how the nervous system coordinates this response, including the roles of the receptor, coordinator and effector.

> OCR A-Level Biology B — Advancing Biology (H422) — 5.7 Nervous communication · Explain · 5 marks

> The nervous system allows the body to detect and respond to changes in the environment. Some responses happen very rapidly without conscious thought.

## Mark scheme (5 marks)

1. A receptor in the skin detects the stimulus (heat / high temperature)
2. A nerve impulse / electrical signal is sent along a sensory neurone to the spinal cord (coordinator)
3. This is a reflex arc, so the spinal cord acts as the coordinator and the response bypasses the brain (allowing a faster response)
4. A nerve impulse travels along a motor neurone from the spinal cord to the effector (muscle)
5. The effector (muscle in the arm) contracts, causing the hand to be pulled away from the hot surface

## Key terms

- [receptor](https://www.gradenine.co.uk/glossary/receptor)
- [coordinator](https://www.gradenine.co.uk/glossary/coordinator)
- [effector](https://www.gradenine.co.uk/glossary/effector)

## Related

- [Revision notes for OCR A-Level Biology B — Advancing Biology (H422)](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-student-touches-a-hot-surface-ac47a5b1) · Published by Druglandscape Ltd.