Voltage-gated ion channels are specialized proteins found in the membranes of cells, particularly in neurons and muscle cells. They open or close in response to changes in the electrical voltage across the cell membrane, allowing specific ions, such as sodium or potassium, to flow in or out of the cell. This movement of ions is crucial for generating and propagating electrical signals in the body. These channels play a vital role in processes like action potentials, which are essential for nerve impulse transmission. When a cell is stimulated, the voltage change triggers these channels to open, leading to rapid changes in ion concentrations that facilitate communication between cells and muscle contractions.