node of Ranvier
Pronunciation: /noʊd ʌv rænˈvieɪ/
Gaps in the myelin sheath along myelinated axons where voltage-gated ion channels cluster for saltatory conduction.
Full Definition
Nodes of Ranvier are regularly spaced unmyelinated gaps along myelinated axons where the axon membrane is exposed to the extracellular environment. These nodes contain high concentrations of voltage-gated sodium and potassium channels, enabling the rapid regeneration of action potentials during saltatory conduction. The spacing between nodes (typically 1-2mm) allows action potentials to 'jump' from node to node rather than traveling continuously along the axon, dramatically increasing conduction velocity. The molecular organization of nodes is maintained by specialized glial cells and involves complex protein interactions that cluster ion channels and maintain structural integrity.
Usage
Usage note: Named after French anatomist Louis-Antoine Ranvier; distinguish from internodal segments.
In Context
- "Electron microscopy revealed disrupted nodes of Ranvier in the peripheral nerve biopsy specimen." — Pathology report
- "The research focused on how nodes of Ranvier are assembled during myelination in development." — Developmental neuroscience paper