The resting membrane potential is typically which value?

The resting membrane potential is typically which value?

• A. -70 mv
• B. -40 mv
• C. 0 mv
• D. +40 mv

Answer: (A)

The resting membrane potential is the steady electrical difference across a neuron's membrane when it’s not signaling. It’s typically around -70 millivolts. This negativity comes from the ion organization and the membrane’s permeability: the inside is rich in negatively charged proteins, and the membrane is more permeable to potassium than to other ions. Potassium tends to leak out, pulling the inside toward a negative value. The Na+/K+ pump helps maintain the gradients by moving more Na+ out and K+ in, which supports the maintenance of this resting potential. Because the membrane isn’t only permeable to K+—there’s some Na+ influx as well—the resting value settles near -70 mV rather than at the more negative K+ equilibrium potential (around -90 mV). If the membrane were at 0 mV or +40 mV, that would indicate a depolarized state, not resting. A value around -40 mV is also more depolarized and closer to the threshold for firing an action potential, which is not the resting condition.

The resting membrane potential is the steady electrical difference across a neuron's membrane when it’s not signaling. It’s typically around -70 millivolts. This negativity comes from the ion organization and the membrane’s permeability: the inside is rich in negatively charged proteins, and the membrane is more permeable to potassium than to other ions. Potassium tends to leak out, pulling the inside toward a negative value. The Na+/K+ pump helps maintain the gradients by moving more Na+ out and K+ in, which supports the maintenance of this resting potential. Because the membrane isn’t only permeable to K+—there’s some Na+ influx as well—the resting value settles near -70 mV rather than at the more negative K+ equilibrium potential (around -90 mV).

If the membrane were at 0 mV or +40 mV, that would indicate a depolarized state, not resting. A value around -40 mV is also more depolarized and closer to the threshold for firing an action potential, which is not the resting condition.