How do the circulatory and excretory systems work together in kangaroo rats to conserve water?

The glomerulus (part of the circulatory system) filters blood, producing a filtrate that enters the nephron.

The kangaroo rat has an exceptionally long loop of Henle (part of the excretory system), which extends deep into the renal medulla. This long loop creates a steep osmotic gradient in the surrounding interstitial fluid. The vasa recta (capillaries of the circulatory system) run parallel to the loop of Henle and collecting duct. They reabsorb water that moves out of the collecting duct due to this osmotic gradient, returning it to the bloodstream and maintaining the gradient, thus conserving water.