nodes of Ranvier
(noun)
Periodic gaps in the myelin sheath where the signal is recharged as it moves along the axon.
Examples of nodes of Ranvier in the following topics:
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Introducing the Neuron
- The synapse is the chemical junction between the axon terminals of one neuron and the dendrites of the next.
- Periodic gaps in the myelin sheath are called nodes of Ranvier.
- At these nodes, the signal is "recharged" as it travels along the axon.
- This neuron diagram also shows the oligodendrocyte, myelin sheath, and nodes of Ranvier.
- The above image shows the basic structural components of an average neuron, including the dendrite, cell body, nucleus, Node of Ranvier, myelin sheath, Schwann cell, and axon terminal.
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Stages of the Action Potential
- As these positive ions rush in, the membrane of the stimulated cell reverses its polarity so that the outside of the membrane is negative relative to the inside.
- Once the electric gradient has reached the threshold of excitement, the "downswing" of repolarization begins.
- In myelinated axons (axons covered by a myelin sheath), this process is described as saltatory because voltage-gated channels are only found at the nodes of Ranvier, and the electrical events seem to "jump" from one node to the next.
- The amplitude of an action potential is independent of the amount of current that produced it.
- The frequency of action potentials is correlated with the intensity of a stimulus.