Is There a Collecting Duct?

Urine that goes through the short loops of henley nefrons, still has the opportunity to become more concentrated when it gets to a collecting duct later on. It is not, by faith, destined to be dilute urine. Just it's because all that atiach activity happens in the collecting duct which is like the stream into which all the little streams empty into. That theat it came from a short loop or a long loop, doesn't really matter as much. The long loop, like melony ad said, sets up that gradient, but the urine itself can all be subject to that gradient later on.