NROB60H3 Chapter Notes - Chapter 4-9: Resting Potential, Sodium Channel, Exosphere
Document Summary
Define membrane potential (v m) and sodium equilibrium potential (e na). The membrane potential (vm) is the voltage across the neuronal membrane at any moment in time. The potential of the resting membrane is 75 mv. The sodium equilibrium potential (ena) is the steady equilibrium potential achieved when the membrane is permeable only to sodium ions. However, in its resting state, the membrane is not permeable to sodium. During the application of action potential, sodium channels open and sodium rushes into the cell. The large sodium current takes the membrane potential from its negative resting state toward ena. During the early part of the action potential, the influx of sodium ions across the membrane briefly depolarizes the membrane. The brief inward sodium current is a consequence of opening the voltage-gated sodium channels for only 1 msec. Membrane repolarization is the result of potassium efflux, which is the outward potassium current because of opening voltage-gated potassium channels after a delay of.
