Question

The point during an action potential when the inside of the cell has become more positive than the outside is known as the

A) depolarization.
B) rising phase.
C) falling phase.
D) overshoot.
E) peak.

Answer 1

The point during an action potential when the inside of the cell is more positive than the outside is known as depolarization. This occurs as a result of Na+ ions entering the cell when the membrane becomes permeable to sodium. The membrane potential reaches its peak positive value during the overshoot.

Step-by-step explanation:

The point during an action potential when the inside of the cell has become more positive than the outside is known as the depolarization. During depolarization, an external stimulus makes the membrane permeable to Na+ ions. This leads to a rapid influx of Na+ ions into the cell, causing a swift change in the membrane potential from negative to positive. This is typically represented by a spike in the voltage graph of the action potential, where the membrane voltage rises towards +30 mV (or even up to +40 mV). The peak of the action potential is when the inside of the cell reaches its highest positive voltage relative to the outside. Repolarization follows depolarization, with K+ ions beginning to leave the cell, bringing the membrane potential back down towards the negative values.

The stages of an action potential can be summarized as follows: (1) Resting potential at -70 mV, (2) Depolarization with Na+ ions entering, (3) Overshoot reaching positive values inside the cell, (4) Repolarization with K+ ions exiting, (5) Membrane potential returns to the resting value after a brief phase of hyperpolarization.