whoa, Lorraine...you're making it tough.....
Henle transports
COUNTERCURRENT SYSTEM and the LOOP OF HENLE
1. The Loop of Henle establishes medullary hyperosmolarity
The ascending limb of the loop of
Henle transports solutes (NaCl) out of the tubule lumen with little or no water, generating an hyperosmotic medullary interstitium and delivering an hyposmotic tubule fluid to the distal tubule. This is called the "single effect".
The osmolarity of the interstitium rises progressively from cortex to medulla and papilla through multiplication of the "single effect" by countercurrent flow in the branches of the loop: The single effect in fluid processed by loop segments located near the tip of the papilla occurs in fluid already subject to the single effect when the fluid was in loop segments located closer to the cortex.
Countercurrent exchange of solutes between ascending and descending vasa recta (the renal medullary capillaries) minimizes solute washout from the medullary interstitium.