And that only happens when the water moves down its gradient from a low solute concentration to a high solute concentration. Now, let's move on to the thin ascending loop of Henley. So, if we look at the following diagram, this is the thin ascending loop of Henley. And unlike our epithelial cells in the descending loop of Henley, the cells here are impermeable to water, but they are permeable to sodium and chloride ions. So the question is, in what direction will the sodium and chloride ions within the thin ascending loop of Henley actually travel? Well, recall that as the filtered travels down the descending loop of Henley, the inside becomes more concentrated, so the relative amount of solutes inside our filtrate increases.