Question

what changes occur to voltage - gated na+ and k+ channels at the peak of depolarization?
activation gates of voltage - gated na+ channels close, while activation gates of voltage - gated k+
channels open.
activation gates of voltage - gated na+ channels close, while inactivation gates of voltage - gated k+
channels open.
inactivation gates of voltage - gated na+ channels close, while activation gates of voltage - gated k+
channels open.
inactivation gates of voltage - gated na+ channels close, while inactivation gates of voltage - gated k+
channels open.

Explanation:

At the peak of depolarization, voltage - gated Na⁺ channels have their inactivation gates close (to prevent further Na⁺ influx) and voltage - gated K⁺ channels have their activation gates open (to allow K⁺ efflux for repolarization).

Answer:

Inactivation gates of voltage - gated Na⁺ channels close, while activation gates of voltage - gated K⁺ channels open.