Question

conduction of a nerve impulse would be the fastest in which of the following?
a small axon with multiple schwann cells
a large unmyelinated axon
a large diameter myelinated axon
a small diameter myelinated axon
a small unmyelinated axon

Explanation:

Analyze factors affecting conduction speed

Using the Myelination knowledge point, myelin sheaths act as electrical insulators that allow action potentials to propagate rapidly via saltatory conduction. Consequently, myelinated axons conduct impulses significantly faster than unmyelinated ones.

Analyze the effect of axon diameter

Axon diameter directly influences internal resistance to current flow. A larger diameter reduces resistance, allowing local currents to spread faster and further down the membrane, which increases conduction velocity.

Combine factors for maximum speed

Combining both optimal features, the fastest nerve impulse propagation occurs in an axon that has both a large diameter and a myelin sheath (myelinated).

Answer:

• A small axon with multiple Schwann cells
• A large unmyelinated axon
• A large diameter myelinated axon (Correct answer)
• A small diameter myelinated axon
• A small unmyelinated axon