Question

Explain why the voltage-gated Na+ channels can close while the cell is depolarized even though the depolarization was the initial stimulus for the channel opening. Include a discussion on refractory periods and explain why action potentials travel in only one direction_____

Answer 1

Voltage-gated Na+ channels close during depolarization due to the absolute refractory period. This ensures that depolarization cannot spread back towards previously opened channels, maintaining the onward propagation of the action potential.

Step-by-step explanation:

Because voltage-gated Na+ channels are inactivated at the peak of the depolarization, they cannot be opened again for a brief time-the absolute refractory period. Because of this, depolarization spreading back toward previously opened channels has no effect. The action potential must propagate toward the axon terminals; as a result, the polarity of the neuron is maintained, as mentioned above.