What is the ratio of Na+/K+ that is pumped in and out of a cell to maintain a constant resting potential?

The sodium-potassium pump, which plays a crucial role in maintaining the resting membrane potential of cells, actively transports sodium and potassium ions across the plasma membrane. This pump utilizes ATP to move three sodium ions out of the cell while bringing two potassium ions into the cell.

The physiological significance of this 3:2 ratio is that, by exporting more positive charges (sodium) than it imports (potassium), the pump contributes to a net negative charge inside the cell relative to the outside environment. This action is vital for maintaining the resting potential, which is typically around -70 mV in many neurons.

By maintaining high concentrations of potassium ions inside the cell and higher sodium concentrations outside, the pump ensures that there is an established electrochemical gradient that is essential for various cellular processes, including action potential generation and neurotransmitter release. Thus, the correct answer correctly describes the mechanism and functioning of the sodium-potassium pump critical for cellular physiology.