CVS Practice Test 2026 – Complete Exam Preparation

In the context of a non-pacemaker action potential (AP), depolarization has a significant effect on the H gates of the Na+ channels. During depolarization, the membrane potential becomes more positive, which influences the gating mechanisms of these ion channels.

When depolarization occurs, the H gates of the Na+ channels, which are responsible for the inactivation of the channel, actually transition into an inactive state instead of remaining in their closed state. This inactivation is crucial as it allows the Na+ ion channel to conduct a brief increase in sodium ion permeability, which further contributes to the rising phase of the action potential.

As the membrane potential rises during depolarization, the voltage-sensitive gates of the channel undergo conformational changes. The rapid influx of sodium ions occurs when the activation gates open, but following this, the H gates close. However, this closure effectively leads to a state of inactivation where the channel cannot be reopened until the membrane repolarizes.

This transition is essential for the proper functioning of action potentials, preventing continuous activation and allowing the neuron to reset for the next potential. Thus, understanding this mechanism provides insight into the dynamics of action potentials and cellular excitability in non-pacemaker cells.