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GCSE Biology · key term
A fatty, electrically insulating layer around an axon or dendron that increases the speed of impulse transmission.
Used by Edexcel and OCR
Specification 2.13 · Paper 1
Revise: Neurones and SynapsesMany long neuronal extensions are surrounded by a fatty myelin sheath. Myelin electrically insulates the neurone. An impulse cannot cross the fatty covering directly, so it effectively jumps from one gap in the sheath to the next.
Paper 1 (Foundation), Paper 2 (Foundation), Paper 3 (Higher), Paper 4 (Higher)
A fatty covering around many axons that insulates them and increases the speed of impulse transmission.
Revise: Neurons and SynapsesMost axons have a fatty myelin sheath around them. This covering insulates the axon and increases the speed at which an impulse travels. At the far end, branched endings allow the neuron to pass its message onwards.
Link each adaptation to its benefit. For example, a long axon carries impulses over long distances, while the myelin sheath insulates the neurone and increases transmission speed.
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