# Explain how inhibitory neurotransmitters can prevent a postsynaptic neuron from generating an action potential.

> IB DP Biology Standard Level (2023 syllabus) — C2.2 Neural signalling · Explain · 4 marks

## Mark scheme (4 marks)

1. Inhibitory neurotransmitters are released from presynaptic vesicles and bind to specific receptors on the postsynaptic membrane.
2. Binding causes ion channels (e.g. chloride or potassium channels) to open, producing an inhibitory postsynaptic potential (IPSP).
3. The membrane becomes hyperpolarised (membrane potential becomes more negative than the resting potential), moving it further from the threshold for an action potential.
4. Because the membrane potential does not reach the threshold, voltage-gated sodium channels are not opened and no action potential is generated.

## Key terms

- [inhibitory neurotransmitter](https://www.gradenine.co.uk/glossary/inhibitory-neurotransmitter)

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Source: [GradeNine](https://www.gradenine.co.uk/q/explain-how-inhibitory-neurotransmitters-can-prevent-7b44f691) · Published by Druglandscape Ltd.