Which mechanism maintains resting membrane potential by pumping Na+ and K+ ions across the membrane?

Which mechanism maintains resting membrane potential by pumping Na+ and K+ ions across the membrane?

• A. Na+/K+-ATPase pump
• B. Voltage-gated Na+ channels
• C. Sodium-glucose cotransporter
• D. Sodium leak channels

Answer: (A)

Maintaining resting membrane potential relies on sustaining ion gradients across the membrane through active transport. The Na+/K+-ATPase uses ATP to move three Na+ ions out of the cell and two K+ ions in, keeping intracellular Na+ low and K+ high. This activity preserves the gradients that underlie the resting voltage and also adds a small net outward current, helping keep the inside of the cell negative. If this pump didn’t work, leak channels would gradually dissipate the gradients and the resting potential would drift toward zero, reducing the cell’s readiness to fire action potentials. The other mechanisms listed don’t actively maintain these ion gradients: some respond to voltage changes, some move ions along with another substrate, and some just contribute to baseline permeability, but none reproduce the ongoing, ATP-powered maintenance of Na+ and K+ distributions like the Na+/K+-ATPase pump.

Maintaining resting membrane potential relies on sustaining ion gradients across the membrane through active transport. The Na+/K+-ATPase uses ATP to move three Na+ ions out of the cell and two K+ ions in, keeping intracellular Na+ low and K+ high. This activity preserves the gradients that underlie the resting voltage and also adds a small net outward current, helping keep the inside of the cell negative. If this pump didn’t work, leak channels would gradually dissipate the gradients and the resting potential would drift toward zero, reducing the cell’s readiness to fire action potentials. The other mechanisms listed don’t actively maintain these ion gradients: some respond to voltage changes, some move ions along with another substrate, and some just contribute to baseline permeability, but none reproduce the ongoing, ATP-powered maintenance of Na+ and K+ distributions like the Na+/K+-ATPase pump.