What is the typical resting membrane potential of most neurons?

• A. Approximately -60 mV
• B. Approximately -50 mV
• C. Approximately -80 mV
• D. Approximately -70 mV

Answer: (D)

At rest, neurons maintain a membrane potential created by a difference in ion concentrations across the membrane and how permeable the membrane is to those ions. The membrane is most permeable to potassium when the neuron is not firing, so the resting potential sits mainly toward potassium’s influence. Potassium’s equilibrium potential is around -90 mV, while sodium’s equilibrium potential is about +60 mV, but because the membrane is far more permeable to potassium at rest, the resting potential ends up closer to -70 mV rather than -90 mV or +60 mV. This makes -70 mV a typical resting value for many neurons. The other options are more depolarized or more hyperpolarized than what is commonly observed in resting conditions.