The Impermeability of the Ascending Lupehenle to Water

The impermeability of the ascending limb to water, which really enables all this stuff to happen. It may not be as tight as a toad bladder, but those tight junctions in the ascending limb of the lupehenle are really tight and they're not even letting water out. And so that the way that your osmolalty of your fluid in the ascending loop of henley is decreasing itis because of salt being pumped out of that fluid and the same amount of water staying there. No water is coming in, only salt is leaving. But at any one layer, at any one level of theloop of henley, you may have relatively small gradient from the inside