Question

What happens to the membrane potential when Na+ channels open and Na+ flows down its concentration gradient into a cell? What happens to the membrane potential when K+ channels open, and K+ flows down its concentration gradient out of a cell?

Answer 1

When Na+ channels open and Na+ flows down its concentration gradient into a cell, it leads to membrane depolarization. In other words, the membrane potential becomes less negative (moves closer to zero) because positive sodium ions are entering the cell, making the interior less negatively charged.

Conversely, when K+ channels open and K+ flows down its concentration gradient out of a cell, it leads to membrane hyperpolarization. In this case, the membrane potential becomes more negative because positive potassium ions are leaving the cell, making the interior more negatively charged.