Final answer:
An open Na+ channel goes through inactivation, then the activation gate closes it, and repolarization reopens it. The Na+/K+ transporter assists in restoring the resting potential to make the channel ready for a new action potential.
Step-by-step explanation:
The open Na+ channel goes through an inactivation process to become inactivated. Then it has an activation gate that closes it. Afterward, the channel requires repolarization to reopen it.
The voltage-gated Na+ channel has two gates. The activation gate opens when the membrane potential crosses -55 mV, and the inactivation gate closes after a fraction of a millisecond. To reopen the channel, first the membrane potential must pass -55 mV again, making the activation gate close, then the inactivation gate re-opens following hyperpolarization, which is facilitated by the Na+/K+ transporter pumping K+ ions into the cell and Na+ ions out, eventually restoring the resting potential and allowing the channel to be ready for the next action potential.