Which term describes the gaps in myelin along an axon?

Which term describes the gaps in myelin along an axon?

• A. Nodes of Ranvier
• B. Schmidt-Lanterman clefts
• C. Synaptic clefts
• D. Nissl bodies

Answer: (A)

Gaps in the myelin along an axon are called nodes of Ranvier. These interruptions in the insulating sheath occur at regular intervals and are rich in voltage-gated sodium channels, which allow the action potential to be re-initiated at each node. This arrangement enables saltatory conduction, where the electrical signal effectively hops from node to node, speeding up transmission compared with continuous conduction along a fully myelinated segment or an unmyelinated fiber. In between, the myelin acts as insulation to limit current leakage, helping the signal reach the next node quickly. For context, Schmidt-Lanterman clefts are small cytoplasmic channels within the Schwann cell's myelin that allow passage of material, not the gaps between myelin segments; synaptic clefts are the extracellular gaps at synapses between neurons; and Nissl bodies are the rough endoplasmic reticulum in the neuron’s soma, unrelated to axonal myelin.

Gaps in the myelin along an axon are called nodes of Ranvier. These interruptions in the insulating sheath occur at regular intervals and are rich in voltage-gated sodium channels, which allow the action potential to be re-initiated at each node. This arrangement enables saltatory conduction, where the electrical signal effectively hops from node to node, speeding up transmission compared with continuous conduction along a fully myelinated segment or an unmyelinated fiber. In between, the myelin acts as insulation to limit current leakage, helping the signal reach the next node quickly. For context, Schmidt-Lanterman clefts are small cytoplasmic channels within the Schwann cell's myelin that allow passage of material, not the gaps between myelin segments; synaptic clefts are the extracellular gaps at synapses between neurons; and Nissl bodies are the rough endoplasmic reticulum in the neuron’s soma, unrelated to axonal myelin.