In a myelinated peripheral nerve fiber, the action potential jumps from one node of Ranvier to the next. Which specific ion channel is highly concentrated at the nodes of Ranvier to enable this saltatory conduction?

• A Voltage-gated calcium channels
• B Ligand-gated sodium channels
• C Voltage-gated sodium channels ✓
• D Leak potassium channels

Explanation

Voltage-gated sodium channels are densely clustered at the nodes of Ranvier, allowing the action potential to leap between nodes and conduct rapidly. Voltage-gated calcium channels are found at presynaptic terminals, not nodes of Ranvier. Ligand-gated channels respond to neurotransmitters, and leak potassium channels primarily maintain the resting membrane potential.

Reference: Ganong's Review of Medical Physiology, 26th ed.

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