Final answer:
A channel that opens when a specific molecule binds to it is called a ligand-gated channel, which is different from voltage-gated channels that respond to changes in membrane voltage.
Step-by-step explanation:
A channel that opens in response to the binding of a specific molecule, which is usually not the solute that passes through the channel, is called a ligand-gated channel. These channels are crucial for the rapid transmission of signals in the nervous system. When a signaling molecule, or ligand, binds to the extracellular region of the channel, such as the neurotransmitter acetylcholine, the pore of the channel opens and allows select ions to flow through, changing the charge across the membrane.
Voltage-gated channels, on the other hand, respond to changes in the electrical properties of the membrane, such as when the transmembrane voltage becomes less negative. The stimulus that causes ligand-gated channels to open is a chemical signal, whereas voltage-gated channels are sensitive to electrical signals. Both types of channels are integral in the functioning of nerve and muscle cells, facilitating the flow of ions that enable electrical impulses.