Reabsorption of water

• is what part of the nephron is the most water reabsorbed?


  proximal convoluted tubule
• how does the loop of Henle work?


  • within each nephron, in the medulla
  • descending limb - permeable to water so as filtrate flows down this part of the loop, its water potential decreases
  • filtrate water potential is lowest at bottom of loop
  • ascending limb - impermeable to water but allows movement of salts out of filtrate so water potential rises again
• what is the function of the loop of henle?


  • to make an increased salt concentration gradient in the medulla, low water potential, by acting as a countercurrent multiplier to produce concentration gradients, for the reabsorption of water
• what are the units used for concentration of solutes in urine?

  • milliosmoles per kilogram (mosm kg-1) - osmorality
  • equivalent to molecules in 1kg of solution