Which term describes gaps in the myelin sheath along a myelinated axon?

Which term describes gaps in the myelin sheath along a myelinated axon?

• A. Node of Ranvier
• B. Myelinated axon
• C. Clefts of Schmidt-Lanterman
• D. Epineurium

Answer: (A)

Nodes of Ranvier are gaps in the myelin sheath along a myelinated axon. These exposed spots on the membrane host a high density of voltage-gated sodium channels, so action potentials are regenerated there and jump from node to node, speeding signal transmission through saltatory conduction. The myelin segments themselves insulate the axon to prevent leakage, with oligodendrocytes forming CNS myelin and Schwann cells forming PNS myelin. Other terms refer to different structures: a myelinated axon is simply the axon wrapped in myelin; Schmidt-Lanterman clefts are small cytoplasmic pockets within peripheral myelin; epineurium is the outer connective tissue layer around a nerve.

Nodes of Ranvier are gaps in the myelin sheath along a myelinated axon. These exposed spots on the membrane host a high density of voltage-gated sodium channels, so action potentials are regenerated there and jump from node to node, speeding signal transmission through saltatory conduction. The myelin segments themselves insulate the axon to prevent leakage, with oligodendrocytes forming CNS myelin and Schwann cells forming PNS myelin. Other terms refer to different structures: a myelinated axon is simply the axon wrapped in myelin; Schmidt-Lanterman clefts are small cytoplasmic pockets within peripheral myelin; epineurium is the outer connective tissue layer around a nerve.