Voltage-gated refers to a type of ion channel in cell membranes that opens or closes in response to changes in electrical voltage. These channels are crucial for the generation and propagation of electrical signals in cells, particularly in neurons and muscle cells. When the membrane potential reaches a certain threshold, the channels open, allowing specific ions, such as sodium or potassium, to flow in or out of the cell. This movement of ions creates an electrical impulse, which is essential for processes like nerve transmission and muscle contraction. Voltage-gated channels are highly selective and play a key role in maintaining the cell's resting potential and responding to stimuli.