Membrane potential

Membrane potential is the difference in electrical charge between the inside and outside of a neuron's plasma membrane, created by the distribution of ions.

• Ion Distribution at Rest

  • Outside the Neuron: Higher concentration of positively charged sodium ions and negatively charged chloride ions.

  • Inside the Neuron: Higher concentration of positively charged potassium ions and negatively charged organic anions.

  • Resting Charge: The interior is more negatively charged than the exterior, establishing a resting membrane potential around $-65\,mV$ to $-70\,mV$.

• Maintenance of Potential

  • Sodium-Potassium Pump: Transport protein that consumes energy to pump three sodium ions out of the neuron for every two potassium ions pumped in, sustaining a net negative internal charge.

  • Potassium Channels: Membrane-spanning proteins that allow potassium to flow freely until reaching equilibrium, stabilizing the resting potential.