So, for instance, we can imagine that this is the lumen of the collecting duct and this is the inside portion of this particular cell. So we have this aquaporne. So we basically have this internal passageway shown here. And these water molecules basically pass along that hydrophilic narrow passageway in a single file. So this passageway is so narrow that they can only make their way across in a single file. And so essentially, this one bumps this one as a result of electrostatic repulsion it, propels it to move this way, and that process continues.