The primary purpose of the sodium-potassium pump is to maintain the electrochemical gradient across the cell membrane. This pump actively transports sodium ions out of the cell while bringing potassium ions in, using ATP. It is essential for various cellular processes, including nerve impulse conduction, muscle contraction, and overall cellular homeostasis. By regulating the concentrations of these ions, the pump contributes to vital physiological functions in both excitatory and non-excitatory cells.