What is reabsorbed in the ascending loop of Henle?

In the ascending loop of Henle, key solutes such as sodium (Na) and chloride (Cl) are reabsorbed. This segment of the nephron is impermeable to water, which means that while solutes are actively transported out of the tubular fluid into the interstitial space, water does not follow. The reabsorption of Na and Cl contributes significantly to the countercurrent multiplier system, which is essential for creating a concentration gradient in the kidney and plays a crucial role in urine concentration.

The cells in this region possess specific transport mechanisms, such as the Na-K-2Cl cotransporter, which helps facilitate this reabsorption process efficiently. This ability to reabsorb sodium and chloride while maintaining water in the tubular fluid allows for the regulation of urine concentration and volume, which is essential for maintaining overall fluid balance in the body.