Membrane Potential (Contd....)

Role of the Sodium and Potassium Pump
  • Since some potassium leaks out of the cell whilst some sodium leaks into the cell, the sodium/potassium pump acts to counter the leaks and maintain the membrane potential

  • Apart from maintaining the equilibrium, the fact that it transports three sodium ions to the outside of the cell to the two potassium ions transported into the cell, thus increasing the membrane potential.

Resting Membrane Potential
  • The resting membrane potential of cells range between -65mV and -85mV (in neurons average -70mV).
  • Thus it is clear that while the resting membrane potential is very near to the potassium equilibrium potential, it is somewhat less. This means that the membrane is not totally impermeable to other ions especially sodium