At the beginning of an action potential,sodium moves
A)slowly into the cell, because electrical force is offset by diffusion.
B) rapidly into the cell, because both electrical force and diffusion operate at the same time.
C) slowly out of the cell, because as a positive ion, sodium remains attracted to the relatively negative intracellular environment.
D) rapidly out of the cell, because the sodium-potassium pumps are very active.

Question

At the beginning of an action potential,sodium moves 
A)slowly into the cell, because electrical force is offset by diffusion. 
B) rapidly into the cell, because both electrical force and diffusion operate at the same time.​ 
C) slowly out of the cell, because as a positive ion, sodium remains attracted to the relatively negative intracellular environment.​ 
D) rapidly out of the cell, because the sodium-potassium pumps are very active.​

Quizplus · Accepted Answer

The movement of sodium during the initiation of an action potential is due to the opening of voltage-gated sodium channels. These channels allow for the rapid influx of sodium ions into the cell, as both the electrical force and concentration gradient (diffusion) favor sodium movement into the cell. This rapid influx of sodium ions creates the depolarization phase of the action potential. Therefore, option B is the best choice.

At the Beginning of an Action Potential,sodium Moves