During the course of an action potential, the membrane potential rapidly rises and reaches a peak of about 40 mV before falling to about - 75 mV. What causes the fall in membrane potential

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Biology

Sandra Davis

9 October, 00:52

During the course of an action potential, the membrane potential rapidly rises and reaches a peak of about 40 mV before falling to about - 75 mV. What causes the fall in membrane potential

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Cyrus Hickman · Answer 1

This is because the voltage gated sodium channels which opens for the influx of sodium ions, which caused increased postivity of the axoplasm closed, with simultaneous opening of potassium channels.

Therefore depolarization stopped, thus propagation and transmission of action potential (caused by depolarization) which cause the reversal of charges in the membrane (making the axoplasm more negative) for the voltage rise to 40mV also stopped.

In addition the simultaneous opening of voltage gated potassium channels caused K + to leave the axoplasm to the external environments. This makes the inner membrane to be negative further lowering the potential, to - 75mv. This is re-polarization.