This portion of a nephron functions to control the amount of water in urine so that concentrated urine is produced when one is dehydrated (low blood volume/pressure) or dilute urine is produced when one is overhydrated (high blood volume/pressure)
The portion of the nephron where the reabsorption of water and ions occurs through water channels, is the Henle Asa. This allows modification of the urine concentration, depending on the needs of the body.