Question

The inactivation gate

A. quickly opens and closes after depolarization.

B. is coupled to the movement of the activation gate, but is much slower.

C. depends on a change of +100 mV from rest to be signaled to close.

D. depends on a loss of Na+ permeability to be triggered.

E. depends on a loss of K+ permeability to be triggered.

Answer 1

The inactivation gate of a voltage-gated Na+ channel closes after membrane depolarization during an action potential, which is slower than the activation gate and essential for neuron reset.

Step-by-step explanation:

The inactivation gate is a crucial component of a voltage-gated Na+ channel in neurons responsible for action potentials. After membrane depolarization, the inactivation gate closes, timed with the peak of depolarization, which prevents further Na+ influx, ensuring the neuron can reset and be ready for another action potential. This mechanism is critical to the proper functioning of nerve cells in transmitting electrical signals.

Choice B is correct. The inactivation gate is indeed coupled to the movement of the activation gate but is much slower. It closes after membrane potential depolarization, limiting further Na+ entry, which is essential for the repolarization phase of the action potential.