Kidney-Water Absorption in LOH Flashcards
What is the loop of henle known as?
Hairpin Counter-Current Multiplier System
Hairpin
Shaped like a hairpin
Counter-Current
Filtrate goes down in descending limb but up in ascending limb
Multiplier
Multiplies the effect of osmosis
Permeability of Descending Limb
Permeable to H2O
Permeability of Ascending Limb
Not permeable to H20
Permeability of Collecting Duct
Permeable to H20 but can be adjusted by ADH
What enters the loop of henle from the PCT?
-40% of H20
-50% of Urea
-Some Na+/Cl- ions
What is the first step of water absorption into blood by the loop of henle?
NA+ and Cl- are pumped by ATP out of ascending limb into medulla which decreases water potential of medulla (-ve water potential)
What is the second step of water absorption into blood by the loop of henle?
H2O therefore moves out of descending limb into medulla/blood by osmosis
What is the third step of water absorption into blood by the loop of henle?
Some Na+ and Cl- diffuse into descending limb
What is the fourth step of water absorption into blood by the loop of henle?
-As filtrate moves down descending limb, H2O leaves but Na+/Cl- enter so at bottom of DL/Loop of Henle/AL so concentration of Na+/Cl- diffuses into medulla
-This decreases water potential inside medulla further so more H2O moves into medulla/blood by osmosis (-ve water potential)
What is the fifth step of water absorption into blood by the loop of henle?
As filtrate moves up ascending limb, Na+/Cl- are being pumped out (step 1) but H2O can’t get out so at top of ascending limb, water potential of filtrate increases
What is the sixth step of water absorption into blood by the loop of henle?
As filtrate moves down collecting duct, more H2O then enters medulla/blood by osmosis
What is the seventh step of water absorption into blood by the loop of henle?
As H2O leaves tubule throughout loop of henle. concentration of urea increases causing some urea to diffuse into medulla further decreasing water potential of medulla so even more water goes to medulla/blood by osmosis (-ve water potential)
