Vasa recta and exchanger
recta and exchanger
The counter-current exchanger mechanism which takes place in the vasa recta is simple enough and its main aim is to keep the hypertonic nature of the loop of Henle's environment. It works in the pyramids which already have become hypertonic. The ascending vasa recta absorbs the solutes using concentration gradient. The solutes are passed into the descending vasa recta and from there back into the pyramidal environment. Hence this counter-current system maintains the hypertonic nature of the environment of the pyramids thereby encouraging osmotic gradient to allow water to flow from the collecting ducts to the same environment. In effect it concentrates urine which otherwise would have been dilute and loose water.
Cross section through kidney; low power
Counter-current multiplier system in the loop of Henle: H - water Na represents Na+ and any other solute.
School of Medicine
Creator: Oluwole Ogunranti