# Explain the role of neurotransmitters in transmitting a nerve impulse across a synapse.

> Edexcel GCSE Biology (1BI0) — 2.3 The nervous system · Explain · 4 marks

> When a nerve impulse reaches the end of one neurone, it cannot jump directly to the next neurone. Instead, a chemical process takes place at the junction between the two neurones.

## Mark scheme (4 marks)

1. A nerve impulse arriving at the synapse causes neurotransmitters to be released (from the presynaptic neurone / synaptic knob / synaptic vesicles)
2. Neurotransmitters diffuse across the synaptic cleft (gap between the two neurones)
3. Neurotransmitters bind to receptors on the postsynaptic (next) neurone
4. Binding of neurotransmitters generates / triggers a new nerve impulse in the postsynaptic neurone

## Key terms

- [neurotransmitters](https://www.gradenine.co.uk/glossary/neurotransmitters)
- [synapse](https://www.gradenine.co.uk/glossary/synapse)
- [nerve impulse](https://www.gradenine.co.uk/glossary/nerve-impulse)

## Related

- [Revision notes for Edexcel GCSE Biology (1BI0)](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/explain-the-role-of-neurotransmitters-in-bbde7e59) · Published by Druglandscape Ltd.