HTHSCI 1H06 Lecture 25: Urine.docx

• School: McMaster University
• Department: Health Sciences
• Course: HTHSCI 1H06
• Professor: Peter Helli

Document Summary

Urine & renal function have to make both kinds; dilute & concentrated. 80: filtrate enters the collecting ducts which, in the absence of adh, are impermeable to water. A bit more solute is pumped out until the most dilute urine is formed: the filtrate enters the thick ascending limb of the loh and solutes are pumped out by symporters but water cannot follow. The filtrate loses solute and the osmolarity goes down. K+-2cl- symporter) to increase the amount of ion in the interstitial fluid. This descending limb of the loh is not permeable to solutes so the solutes stay in the lumen of the descending limb tubule and the osmolarity of the fluid increases all the way to the bottom of the loop. Renal medulla: filtrate enters loh and equilibrates. The loss of water makes the filtrate more concentrated and the osmolarity goes up.