# Explain how the structure of a neuron (nerve cell) is adapted for the rapid transmission of electrical impulses over long distances.

> IB DP Biology Standard Level (2023 syllabus) — B2.3 Cell specialisation · Explain · 4 marks

## Mark scheme (4 marks)

1. The axon is elongated/very long, allowing impulses to be conducted over long distances without interruption.
2. The myelin sheath (formed by Schwann cells) electrically insulates the axon, increasing the speed of impulse transmission by saltatory conduction.
3. Numerous mitochondria are concentrated at the synaptic terminals / along the axon to supply ATP for active transport of ions (maintaining resting potential / reuptake of neurotransmitters).
4. Dendrites are highly branched, increasing the surface area to receive signals from many other neurons simultaneously.

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