During depolarization, the membrane potential moves from -90 mV to which value?

During depolarization, the membrane potential moves from -90 mV to which value?

• A. -70 mV
• B. -40 mV
• C. +30 mV
• D. 0 mV

Answer: (C)

Depolarization is when the membrane potential becomes less negative as voltage-gated Na+ channels open and Na+ rushes into the cell. Starting from -90 mV, this rapid inward current drives the potential toward positive values, typically reaching about +30 mV at the peak of the cardiac action potential. So the membrane potential moves to a value around +30 mV during depolarization. Resting levels are around -90 to -70 mV, -40 mV reflects an earlier depolarization or threshold stage, and 0 mV is an intermediate point—not the peak. Afterward, repolarization brings the potential back toward negative values.

Depolarization is when the membrane potential becomes less negative as voltage-gated Na+ channels open and Na+ rushes into the cell. Starting from -90 mV, this rapid inward current drives the potential toward positive values, typically reaching about +30 mV at the peak of the cardiac action potential. So the membrane potential moves to a value around +30 mV during depolarization. Resting levels are around -90 to -70 mV, -40 mV reflects an earlier depolarization or threshold stage, and 0 mV is an intermediate point—not the peak. Afterward, repolarization brings the potential back toward negative values.