Final answer:
Repolarization and the action of the sodium-potassium pump restore the ion gradients across a neuron's membrane following the action potential.
Step-by-step explanation:
Following the action potential, the ion gradients across a neuron's membrane are restored through the process of repolarization. During repolarization, voltage-gated potassium channels open, allowing the outflow of K+ ions, which brings the membrane potential back to its resting state. Additionally, the sodium-potassium pump continuously transports Na+ ions out of the cell and K+ ions into the cell, maintaining the concentration differences necessary for the ion gradients.
The sodium-potassium pump then works actively to move Na+ ions out of the cell and K+ ions back into the cell, against their respective concentration gradients, which is an energy-consuming process utilizing ATP. This pumping action helps maintain the resting membrane potential and reestablishes the ion gradients, allowing the neuron to be ready for the next action potential.