A cell membrane is a protective barrier that encloses a cell and allows nutrients and waste to pass back and forth. The cell membrane has passageways that allow for the transport of things from the inside and outside of the cell.The inside and outside of a cell will have differing electrical charges (positive and negative) depending on what kinds of nutrients are in and around the cell.
Depolarization is a change in the difference between the electric charge on the inside and the outside of the cell membrane and is when the cell becomes positively charged (or less negative). The electrical charge changes because of molecules entering or leaving the cell - molecules can have a positive or a negative charge. Hyperpolarization is the opposite of depolarization and is when the cell is becoming more negatively charged.