An above-threshold depolarizing current is applied to the cell, but it is slightly above the required threshold for the action potential. As a result, __________.
A) the action potential occurs more slowly
B) the action potential will be the same size and propagated at the same speed as if the depolarizing current was applied at threshold levels
C) the action potential occurs more quickly and is larger
D) the action potential will be smaller and propagated slightly slower than if the depolarizing current was applied at threshold levels

Question

Quizplus · Accepted Answer

If the depolarizing current is slightly above threshold level, the action potential will still occur at its typical size and conduction speed. This is because the threshold level is the point where enough voltage-gated ion channels have opened to generate an action potential. Once this threshold is met, further depolarization only ensures that more ion channels will be activated, but it doesn't change the action potential characteristics themselves. Therefore, the size and speed of the action potential will not be affected by a slightly higher depolarizing current.

An Above-Threshold Depolarizing Current Is Applied to the Cell, but It