All cells in animal body tissues are electrically polarized.
Depolarization is when the membrane potential becomes less negative (more positive).
The inward flow of sodium ions increases the concentration of positively charged cations in the cell and causes depolarization,
Hyperpolarization is when the membrane potential becomes more negative at a particular spot on the neuron’s membrane.The opening of channels that let positive ions flow out of the cell (or negative ions flow in) can cause hyperpolarization.
Depolarization is primarily linked with sodium, whereas hyperpolarization is mainly linked with calcium.