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GCSE Biology · key term
A chemical messenger released by a transmitting neurone that diffuses across a synaptic gap and binds to receptors on the next neurone.
Used by Edexcel and OCR
Specification 2.13 · Paper 1
A chemical released from the end of a neurone that diffuses across a synaptic gap and can trigger a new electrical impulse in the next neurone.
Revise: Neurones and SynapsesThis causes vesicles in the ending to release a chemical neurotransmitter into the synaptic gap.
Specification B3.1a · Paper 1 (Foundation), Paper 3 (Higher)
Do not say that an electrical impulse crosses the synaptic gap. Describe the sequence: neurotransmitter is released, diffuses across the gap, binds to receptors and triggers a new electrical impulse.
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.
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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. This stimulates a new electrical impulse in that neurone.
Paper 1 (Foundation), Paper 2 (Foundation), Paper 3 (Higher), Paper 4 (Higher)
A chemical released by one neuron that diffuses across a synapse and binds to receptors on the next neuron.
Revise: Neurons and SynapsesWhen 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. This stimulates the next neuron to carry an electrical impulse along its own axon.