What is saltatory conduction?

What is saltatory conduction?

• A. The process by which action potentials jump between nodes of Ranvier along myelinated axons.
• B. Propagation of action potentials along unmyelinated fibers only.
• C. A chemical signal transmitted at the synapse.
• D. The decay of an action potential over distance.

Answer: (A)

Saltatory conduction is the rapid propagation of the action potential by jumping from one node of Ranvier to the next along a myelinated axon. The myelin sheath increases membrane resistance and lowers membrane capacitance, so the depolarizing current travels quickly through the insulated segments and only the nodes, where many voltage-gated Na+ channels reside, regenerate the spike. This nodal renewal makes conduction faster than in unmyelinated fibers and more energy-efficient, since fewer ion channels must open and fewer ions must be pumped back out. The other ideas describe processes that aren’t saltatory conduction: a chemical signal at a synapse, propagation along unmyelinated fibers, or decay of the signal over distance.

Saltatory conduction is the rapid propagation of the action potential by jumping from one node of Ranvier to the next along a myelinated axon. The myelin sheath increases membrane resistance and lowers membrane capacitance, so the depolarizing current travels quickly through the insulated segments and only the nodes, where many voltage-gated Na+ channels reside, regenerate the spike. This nodal renewal makes conduction faster than in unmyelinated fibers and more energy-efficient, since fewer ion channels must open and fewer ions must be pumped back out. The other ideas describe processes that aren’t saltatory conduction: a chemical signal at a synapse, propagation along unmyelinated fibers, or decay of the signal over distance.