Which structures on the axon serve as the sites where action potentials 'jump' during saltatory conduction?

• A. Dendritic spines
• B. Axon hillock
• C. Nodes of Ranvier
• D. Synaptic terminals

Answer: (C)

Verified step by step guidance

1. Understand the concept of saltatory conduction: Saltatory conduction is the process by which action potentials travel along myelinated axons by 'jumping' from one node to the next, rather than propagating continuously along the axon.
2. Learn about the structure of a myelinated axon: Myelinated axons are covered by a fatty substance called myelin, which insulates the axon and speeds up the transmission of electrical signals. The myelin sheath is interrupted at regular intervals by gaps called Nodes of Ranvier.
3. Identify the role of Nodes of Ranvier: These nodes are the sites where voltage-gated ion channels are concentrated. During saltatory conduction, action potentials are regenerated at these nodes, allowing the signal to 'jump' from one node to the next.
4. Differentiate between the given options: Dendritic spines are structures on dendrites, not axons. The axon hillock is the site where action potentials are initiated, not where they jump. Synaptic terminals are the ends of axons where neurotransmitters are released, not involved in saltatory conduction.
5. Conclude that the correct answer is Nodes of Ranvier, as they are the specific structures on the axon where action potentials 'jump' during saltatory conduction.