The functional role of the loop of Henle is that of concnetrating the urine and thus to conserve water. This is achieved through the countercurrent mechanism. The countercurrent mechanism depends on a peculiar anatomical arrangement of the loop of Henle and the Vasa Recta. The loop of Henle dips from the cortex deep into the medulla. The vasa recta parallel the loop of henle, i.e. loop from the cortex into the medulla.