Question

Describe the movement of K+ and Cl- ions across the plasma membrane to restore resting membrane potentials.

A. K+ moves out of the cell through leak channels, and Cl- enters through active transport, both contributing to membrane repolarization.
B. K+ moves into the cell through active transport, and Cl- exits through leak channels, both contributing to membrane depolarization.
C. K+ moves out of the cell through active transport, and Cl- exits through leak channels, both contributing to membrane depolarization.
D. K+ moves into the cell through leak channels, and Cl- enters through active transport, both contributing to membrane repolarization.

Answer 1

K+ ions move out of the cell through leak channels to contribute to membrane repolarization. Cl- ions movement is passive and does not require active transport for repolarization. The correct answer to the student's question is A: K+ moves out of the cell through leak channels, and Cl- enters through active transport, both contributing to membrane repolarization.

Step-by-step explanation:

During the process of restoring the resting membrane potential, K+ ions move out of the cell through leak channels, and this outflow of positively charged ions contributes to the repolarization of the membrane. Repolarization is the process by which the membrane potential returns towards the resting level of approximately -70 mV. Conversely, Cl- ions typically follow their electrochemical gradient and may move in or out of the cell, although in many neurons, they passively distribute across the membrane without requiring active transport mechanisms.

During the action potential, when the membrane potential becomes positively charged, the outflow of K+ ions through their specific channels assists in bringing the membrane potential back down, thus contributing to the repolarization process. This action works in concert with the Na+/K+ pump, an example of active transport, which uses ATP to restore the ion concentration gradients across the membrane. While Cl- ions do not have a significant role in repolarization, they do help maintain overall electrochemical balance.