Active Transport definition: movement of materials across a membrane that requires an input of energy from a cell.
Active transport of ions across the nerve cell membrane maintains a cell's resting potential. Even at rest, nerve cell membranes have an electrical potential-that is, the interior of a nerve cell has a negative electrical charge relative to the cell's external environment, which is positive.
The electrical potential that exists in a nerve cell membrane when it is at rest is called a resting potential. That resting potential is maintained by an active transport mechanism called the sodium-potassium pump. The sodium-potassium pump is a series of proteins embedded in the cell's membrane. It uses the energy of ATP to move sodium ions -NaK- out of the cell and potassium ions -KK- into the cell.
When a flash of energy is required to move materials through a cell membrane, it is called active transport. The cell membrane helps an organism respond to its environment. Cell membranes are key structures that help organisms maintain homeostasis.
