What is the primary characteristic of the nodes of Ranvier in peripheral nerves?
Solution
Correct Answer: Option B
- The nodes of Ranvier are specialized structures found along myelinated peripheral nerves.
- These nodes are characterized by being gaps in the myelin sheath, where the axon membrane is exposed to the extracellular environment.
- This structural arrangement is crucial because it allows for the rapid propagation of electrical impulses via a mechanism called saltatory conduction.
- In saltatory conduction, the action potential “jumps” from one node to the next, significantly increasing the speed of nerve impulse transmission compared to continuous conduction along unmyelinated fibers.
- The high concentration of voltage-gated sodium channels at the nodes facilitates the regeneration of the action potential, ensuring efficient and rapid signal conduction.
- Other options such as sites of neurotransmitter release (Option 1) and regions of synaptic contact between neurons (Option 3) are related to synapses, not the nodes of Ranvier. Option 4, specialized ion channels for resting membrane potential, refers generally to ion channels but does not specifically define the primary characteristic of the nodes.
In summary, the primary characteristic of the nodes of Ranvier in peripheral nerves is that they are gaps in the myelin sheath facilitating saltatory conduction.
Reference: Guyton and Hall Textbook of Medical Physiology, 14th Edition, Chapter 6, Page 64
- These nodes are characterized by being gaps in the myelin sheath, where the axon membrane is exposed to the extracellular environment.
- This structural arrangement is crucial because it allows for the rapid propagation of electrical impulses via a mechanism called saltatory conduction.
- In saltatory conduction, the action potential “jumps” from one node to the next, significantly increasing the speed of nerve impulse transmission compared to continuous conduction along unmyelinated fibers.
- The high concentration of voltage-gated sodium channels at the nodes facilitates the regeneration of the action potential, ensuring efficient and rapid signal conduction.
- Other options such as sites of neurotransmitter release (Option 1) and regions of synaptic contact between neurons (Option 3) are related to synapses, not the nodes of Ranvier. Option 4, specialized ion channels for resting membrane potential, refers generally to ion channels but does not specifically define the primary characteristic of the nodes.
In summary, the primary characteristic of the nodes of Ranvier in peripheral nerves is that they are gaps in the myelin sheath facilitating saltatory conduction.
Reference: Guyton and Hall Textbook of Medical Physiology, 14th Edition, Chapter 6, Page 64
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