Myelinated nerves help local currents travel ______ than an unmyelinated nerve; it occurs by current leaps from node to node called ______ conduction.

Myelinated nerves help local currents travel ______ than an unmyelinated nerve; it occurs by current leaps from node to node called ______ conduction.

• A. Faster, Saltatory
• B. Slower, Continuous
• C. Equally fast, Retrograde
• D. Faster, Diffusive

Answer: (A)

Myelin makes nerve fibers conduct signals more quickly by changing how the electrical current travels along the axon. The myelin sheath increases membrane resistance and lowers capacitance in the insulated portions (internodes), so the current leaks less and can travel farther without losing strength. The action potential is generated at the nodes of Ranvier, where many voltage-gated Na+ channels are located, and when the local current reaches the next node, it triggers another action potential. This creates a jumping, or saltatory, conduction from node to node, which is much faster than the continual depolarization required along every point of an unmyelinated axon.

Myelin makes nerve fibers conduct signals more quickly by changing how the electrical current travels along the axon. The myelin sheath increases membrane resistance and lowers capacitance in the insulated portions (internodes), so the current leaks less and can travel farther without losing strength. The action potential is generated at the nodes of Ranvier, where many voltage-gated Na+ channels are located, and when the local current reaches the next node, it triggers another action potential. This creates a jumping, or saltatory, conduction from node to node, which is much faster than the continual depolarization required along every point of an unmyelinated axon.