Question

Which of the following occurs when a stimulus depolarizes a neuron's membrane to a membrane potential below the voltage threshold?

A. The action potential approaches zero.
B. The action potential stops spreading to the next dendrite.
C. The membrane potential changes from the resting potential to a more negative membrane potential.
D. The inside of the cell becomes less negative in charge relative to the outside of the cell.

Answer 1

Answer: D. The inside of the cell becomes less negative in charge relative to the outside of the cell.

During depolarization, the membrane potential moves towards zero. This process is initiated by $Na^{+}$ that enters the cell due to the polarization of the cell. Outside of the cell, the concentration of the positively charged sodium ion is higher by a factor of 10, compared with the interior of the cell. Due to the presence of the sodium cation in increasing amounts inside the cell, the relative voltage will change immediately. This will result in an interior of the cell that is less negative in charge relative to the outside of the cell.