Now, although gap junctions are in fact on channels, they have very different properties from the properties of voltage gated and ligand gated on channels. And there are five important things that differentiate gap junctions from voltage gated and ligand gated on channels. So let's begin by comparing and contrasting these different types of on channels. So voltage gated channels and ligand gated channels are actually closed when that membrane is the rest, and they're only open when that membrane is excited by some type of stimulus. Now, when they do open, they're only open for a very short period of time, about a milliseconds or so, and then they're quickly closed off or they're inactivated. And the size of the pore inside these channels is actually very small.