What is the resting membrane potential of a neuron?

What is the resting membrane potential of a neuron?

• A. -70 mV.
• B. -50 mV.
• C. -90 mV.
• D. +40 mV.

Answer: (A)

Resting membrane potential reflects the balance of ionic gradients and the membrane’s selective permeability. At rest, the inside of the neuron is more negative because potassium leak channels allow K+ to diffuse out, making the inside negative. While the potential moves toward the potassium equilibrium value (around -90 mV), there is also some sodium permeability and the Na+/K+ pump maintains gradients, so the steady state settles near -70 mV in many neurons. That’s why -70 mV is the typical resting value. A more positive value (like around -50 mV) would indicate depolarization, and -90 mV is closer to the K+ equilibrium but not what neurons typically sit at at rest due to Na+ leak and pump activity; +40 mV would be a depolarized, active state.

Resting membrane potential reflects the balance of ionic gradients and the membrane’s selective permeability. At rest, the inside of the neuron is more negative because potassium leak channels allow K+ to diffuse out, making the inside negative. While the potential moves toward the potassium equilibrium value (around -90 mV), there is also some sodium permeability and the Na+/K+ pump maintains gradients, so the steady state settles near -70 mV in many neurons. That’s why -70 mV is the typical resting value. A more positive value (like around -50 mV) would indicate depolarization, and -90 mV is closer to the K+ equilibrium but not what neurons typically sit at at rest due to Na+ leak and pump activity; +40 mV would be a depolarized, active state.