So we'll summarize our discussion. So we see that the collecting duct is actually under the control of these hormones, ADH, as well as our aldosterone. In the absence of these hormones, the collecting duct is impermeable to water. And only about 5% of the sodium, total sodium, in the filtrate, is actually absorbed by the collecting duct. However, when we have the hormone hormones present along this region, these hormones basically stimulate. They force our collecting duct to become permeable to water.