Heat causes which of the following changes in nerve conduction velocity?

Heat causes which of the following changes in nerve conduction velocity?

• A. Increased nerve conduction velocity
• B. Decreased nerve conduction velocity
• C. No change in conduction velocity
• D. Irregular conduction with pauses

Answer: (A)

Heat speeds up nerve conduction because temperature accelerates the kinetic processes in nerve membranes and ion channels. When temperature rises within physiological limits, the rate at which voltage-gated sodium and potassium channels open and close increases, and the membrane can charge and discharge more quickly at each node of Ranvier. This reduces the time constants for depolarization and repolarization, so the action potential propagates along the axon more rapidly, increasing conduction velocity. Just keep in mind that this favorable effect occurs only up to a point; excessive heat can damage proteins and disrupt conduction. In contrast, cooling slows channel kinetics and slows conduction, and unusually irregular conduction with pauses typically points to extreme temperature effects or other nerve damage rather than normal heating.

Heat speeds up nerve conduction because temperature accelerates the kinetic processes in nerve membranes and ion channels. When temperature rises within physiological limits, the rate at which voltage-gated sodium and potassium channels open and close increases, and the membrane can charge and discharge more quickly at each node of Ranvier. This reduces the time constants for depolarization and repolarization, so the action potential propagates along the axon more rapidly, increasing conduction velocity.

Just keep in mind that this favorable effect occurs only up to a point; excessive heat can damage proteins and disrupt conduction. In contrast, cooling slows channel kinetics and slows conduction, and unusually irregular conduction with pauses typically points to extreme temperature effects or other nerve damage rather than normal heating.