Resting Membrane Potential: How Neurons Maintain Polarization

The resting membrane potential (~ -70 mV) is maintained by:

1. Ion Concentration Gradients: High intracellular K⁺, high extracellular Na⁺ established by Na⁺/K⁺-ATPase pump.
2. Selective Permeability: Resting K⁺ channels allow K⁺ efflux, creating negative interior.
3. Na⁺/K⁺ Pump: Actively transports 3 Na⁺ out, 2 K⁺ in per ATP, maintaining gradients.
4. Leak Channels & Electrogenic Pump: Minor Na⁺ influx balanced by pump’s net positive charge export.
5. Cl⁻ Distribution: Extracellular Cl⁻ enters via leaks; negative charge offset by K⁺ efflux, maintaining electroneutrality.

These mechanisms ensure stable resting potential, essential for neuronal excitability and signaling.