What is exclusively reabsorbed in the Descending Loop of Henle?

The descending loop of Henle is primarily involved in the reabsorption of water. This segment of the nephron is permeable to water due to the presence of aquaporin channels. These channels allow water to move out of the tubule and into the surrounding interstitial fluid, which has a higher osmolarity. As a result, water follows the osmotic gradient, effectively concentrating the urine as it flows through this part of the loop.

In contrast, the descending loop is not permeable to solutes like sodium, glucose, or bicarbonate, which is why these substances are not reabsorbed in this segment. Understanding the specific functions of different nephron segments is crucial for grasping the overall process of urine formation and concentration within the kidney.