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A junction between two neurones where a chemical neurotransmitter carries the signal across a small gap.

A junction between neurones where a chemical messenger transmits a signal across a small gap.

At each synapse, an arriving electrical impulse causes a chemical messenger, called a neurotransmitter, to cross the small gap between neurones. This starts a new electrical impulse in the next neurone. A typical withdrawal arc has a synapse between the sensory and relay neurones and another between the relay and motor neurones.

Do not call a synapse a neurone: it is the junction across which a chemical messenger passes.

Include the synapses when explaining how the impulse passes between the sensory, relay and motor neurones.

At a synapse, state that a chemical neurotransmitter diffuses across the gap and starts a new electrical impulse in the next neurone; the electrical impulse itself does not cross the gap.

Where one neurone communicates with the next, there is a junction called a synapse, which includes a tiny gap. The electrical impulse cannot travel directly across this gap, so transmission briefly changes from electrical to chemical and then back to electrical.

A tiny junction between neurones across which a chemical neurotransmitter carries the signal.

The tiny junction between one neurone and the next is a synapse. When an electrical impulse reaches the end of the first neurone, it causes a chemical called a neurotransmitter to be released. The neurotransmitter diffuses across the gap and binds to receptor molecules embedded in the gap-facing membrane of the next neurone.

A small gap between neurones across which a signal is transmitted using neurotransmitters.

The junction between two neurons where a signal passes across a small gap using chemical transmitter substances.

The junction between them is a synapse, with a tiny gap between the end of the first neuron and the membrane of the next. When an impulse reaches the first neuron's ending, it causes transmitter substances, also called neurotransmitters, to be released. These chemicals diffuse across the gap and bind to receptors on the next neuron.

Synapse

Definition

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AQA GCSE Biology · 8461

Edexcel GCSE Biology · 1BI0

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OCR GCSE Biology A · J247

OCR GCSE Biology B · J257