What is a key characteristic of the Na+ pump in nerve cells?

The Na+ pump, also known as the sodium-potassium ATPase, plays a critical role in maintaining the resting membrane potential of nerve cells. This pump actively transports sodium ions (Na+) out of the cell and potassium ions (K+) into the cell, typically in a ratio of three sodium ions expelled for every two potassium ions brought in. This action creates and maintains a concentration gradient that is essential for the resting membrane potential, typically around -70 mV in neurons.

The resting potential is vital for the proper functioning of nerve cells, as it sets the stage for the generation of action potentials. If the resting potential is not maintained, the neuron may become depolarized abnormally, disrupting normal signaling processes. Thus, the key characteristic of the Na+ pump is its crucial function in sustaining the resting potential, which is foundational for the overall excitability and functionality of nerve cells.