Explore BrainMass

Resting membrane potential maintenance

Explain how the axonal membrane potential is restored following action potential depolarization. Describe how resting ionic distributions are maintained.

Solution Preview

How does the axonal membrane potential become restored following action potential depolarization?

The depolarizing event not only opens voltage-gated Na+ channels. It also opens voltage-gated K+ channels. These potassium channels open more slowly than the sodium channels. As a result, they open about the same time as the sodium channels are closing. These two events together, result in a repolarization of the membrane potential. As the sodium channels are inactivitated, Na+ movement into the cell slows down. Concurrently, as K+ channels open, potassium ions move out of the cell. These two actions together change the membrane potential from about +30 mV to -70 mV.

Interestingly, the outflow of K+ can be so great and so rapid, that it actually leads to a hyperpolarizing effect. In other words, for a brief amount of time, the membrane potential can go all the way down to -90 mV. As these K+ channels ...

Solution Summary

The expert explains how the axonal membrane potential is restored. The action potential depolarization is analyzed. The expert describes how resting ionic distributions are maintained.