osmosis

Descending Limb Of Loop Of Henle.

absorption of water (from descending limb), absorption of Na+ (from ascending limb) 

The function of the ascending loop of henle is draw Sodium out of the filtrate. The ability of the ascending loop to actively transport sodium into the surrounding tissue is directly related to the amount of water that can be diffused out of the descending loop of henle. (main factor in water re-absorption)

# Water is reabsorbed all along the nephron. # Urine becomes hypertonic (salty) because of the loop of Henle and the collecting duct. # Loop of Henle # The descending limb of the loop of Henle can't absorb salt, and the ascending limb can't absorb water. # Salt passively diffuses out of the lower portion of the ascending limb. # The upper part of ascending limb actively transports salt into tissue of the renal medulla. # Increase in salt in the direction of the inner medulla. # Urea leaks from the lower portion of collecting duct and contributes to a high solute (salt) concentration. # Water leaves descending limb of the loop of Henle, returning to the blood. # Urine is hypertonic to blood.