Final answer:
The sodium-potassium pump helps regulate cell volume by moving three sodium ions out and two potassium ions in using ATP, which also maintains the cell's electrochemical gradient and prevents cell swelling by controlling water inflow.
Step-by-step explanation:
How the Sodium-Potassium Pump Regulates Cell Volume
The sodium-potassium pump, also known as Na+/K+ ATPase, plays a crucial role in maintaining cell volume by moving ions across the cell membrane against their concentration gradients. In a single cycle, this pump extrudes three sodium ions (Na+) from the cell and imports two potassium ions (K+) into the cell, using energy from ATP. This action not only helps in maintaining the cell's electrochemical gradient but also its osmotic balance, which in turn regulates cell volume. A net loss of positive ions occurs due to more sodium ions being pumped out than potassium ions being brought in, preventing water from flooding into the cell and thus maintaining its size and preventing swelling.
Specifically, by pumping out more ions than it takes in, the sodium-potassium pump keeps the intracellular ion concentration lower than the outside, which helps manage the inflow of water. If more water entered the cell than necessary, it would lead to cell swelling and potentially bursting. This pump is especially critical in nerve cells, where it also maintains the electrical gradient, crucial for nerve impulse transmission.