A myelinated axon has a conduction velocity of 120 m/s. A motor impulse travels 0.6 m from the spinal cord to a muscle. Calculate the time taken for the impulse to reach the muscle and state how this timing is relevant to a rapid defensive reflex.

Step-by-step solution

1. Time = distance ÷ velocity = 0.6 m ÷ 120 m/s = 0.005 s.
2. Convert seconds to milliseconds: 0.005 s = 5 ms.
3. Such short conduction time allows the body to react quickly in a defensive reflex, like pulling a hand away from a hot surface.

Concept tested: Conduction velocity and reflex timing

Published 16 October 2026 · How this solution was prepared and checked