Active transport is a process requiring energy in which a substance crosses the cell membrane. In a resting neuron, there are positively charged sodium ions outside of the cell, and negatively charged potassium ions in the cell. When the neuron fires, depolarization occurs=> the positive ions are forced in and negative ions are forced out by means of active transport. When the neuron is done firing, the ions are forced back into their original position inside or outside of the cell by active transport.
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