Final answer:
Voltage-gated ion channels open in response to changes in electrical membrane potential, while ligand-gated ion channels open when a ligand such as a neurotransmitter binds to them. Both play critical roles in cell signaling and membrane potential changes.
Step-by-step explanation:
Differentiating between voltage-gated and ligand-gated ion channels is fundamental in understanding how electrical signals are propagated in neuronal and muscle cells. Voltage-gated ion channels open in response to changes in membrane voltage. For example, when the inner portion of a cell's membrane becomes less negative, these channels open, allowing ions to cross the membrane. Once activated, they remain inactive for a period where they will not open again despite further signaling, which is crucial in the transmission of electrical impulses along nerve and muscle cells.
Conversely, ligand-gated ion channels open when a signaling molecule, or ligand, binds to the extracellular region of the channel protein. These are also known as ionotropic receptors. Common ligands include neurotransmitters like acetylcholine, which, upon binding to the channel, allows ions such as sodium, calcium, and potassium to cross the membrane, changing the membrane's charge.