BISC 162 Lecture 1: Journal 6 (Bio Leecture)

• School: UM
• Department: Biology
• Course: BISC 162

Document Summary

A countercurrent multiplier is established in the kidneys to create a concentration gradient for the reabsorption of water and ions from the filtrate. This concentration gradient is important for the production of concentrated urine. The countercurrent multiplier involves the loop of henle, which is divided into a descending limb and an ascending limb. The descending limb of the loop of henle is permeable to water but not to ions, while the ascending limb is impermeable to water but actively pumps ions out of the filtrate. The countercurrent multiplier works by creating a gradient of increasing concentration of ions in the interstitial fluid surrounding the ascending limb of the loop of henle. The ascending limb actively transports sodium and chloride ions out of the filtrate and into the interstitial fluid. This creates a concentration gradient where the concentration of ions is higher in the interstitial fluid near the bottom of the loop of henle than it is at the top.