# Describe how a nerve impulse travels from a receptor to an effector when a person touches a hot object and quickly pulls their hand away. Include the names of the neurones involved in your answer.

> Eduqas A-Level Biology — 3.8 The nervous system · Describe · 5 marks

## Mark scheme (5 marks)

1. A receptor in the skin detects the stimulus (heat/pain)
2. A sensory neurone carries the impulse from the receptor to the central nervous system (spinal cord / brain)
3. A relay neurone (in the spinal cord / CNS) passes the impulse on
4. A motor neurone carries the impulse from the CNS to the effector (muscle)
5. The effector (muscle) responds by contracting, causing the hand to be pulled away

## Key terms

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

## Related

- [Revision notes for Eduqas A-Level Biology](https://www.gradenine.co.uk/learn)
- [How to answer "Describe" 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/describe-how-a-nerve-impulse-travels-3ddbdbc5) · Published by Druglandscape Ltd.