Neurophysiology and Synapses · USMLE Step 1

Which of the following correctly explains why myelinated axons conduct action potentials faster than unmyelinated axons?

  1. Myelinated axons have more ligand-gated ion channels along their length.
  2. Myelin increases the density of synapses along the axon.
  3. Myelin insulates the axon, allowing saltatory conduction between nodes of Ranvier.
  4. Myelinated axons release neurotransmitter faster.
Show answer and explanation

Correct answer: Myelin insulates the axon, allowing saltatory conduction between nodes of Ranvier.

Myelin insulates the axon and forces action potentials to jump between the nodes of Ranvier (saltatory conduction), significantly increasing conduction velocity compared with continuous propagation in unmyelinated axons.

Difficulty: Medium Question 17 of 28

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