A recording electrode is placed into a nerve cell to measure the membrane potential at a particular point. When the physiologist glances at the recording and sees that the membrane at that instant has a potential of +15 mV, she knows that the portion of the membrane being recorded is which of the following? A)in the normal resting state B)in the reversal phase of an action potential when the inside of the cell becomes more positive than the outside C) more permeable to Ca²⁺ than normal D) in the after hyperpolarization phase of an action potential

Question

Quizplus · Accepted Answer

A positive membrane potential indicates that the inside of the cell is more positive than the outside, which occurs during the reversal phase of an action potential. Therefore, the portion of the membrane being recorded is in the process of firing an action potential. The other choices (A, C, and D) are not consistent with a positive membrane potential.

A Recording Electrode Is Placed into a Nerve Cell to Measure