Node of Ranvier
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- This article is about the anatomical characteristic of neurons. For the band, see Nodes of Ranvier (band).
Nodes of Ranvier are regularly spaced gaps in the myelin sheath around an axon or nerve fiber. About one micrometer in length, these gaps expose the membrane of the axon to the surrounding liquid.
An action potential is the sharp electrochemical response of a neuron that has been stimulated, or whose membrane potential has been changed by a nearby cell or an experimentor. In an action potential, the cell membrane potential changes drastically and quickly as ions flow in or out of the cell. The action potential "travels" from one place in the cell to another, but ion flow occurs only at the nodes of Ranvier. Therefore, the action potential signal "jumps" along the axon, from node to node, rather than propagating smoothly, as they do in axons that lack a myelin sheath. This is known as saltatory conduction.de:Ranvierscher Schnürring