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. And at the bottom of our loop, we have a hypertonic environment. Hypertonic with respect to our interstitium, we have a high concentration of sodium and chloride. And because our cells within our thin ascending lupinly allow the movement of sodium and chloride passively, these sodium and chloride ions will move down their electrochemical gradient from a hypertonic environment, from where we have a high concentration of solute, to a low where we have a lower concentration.