The Loop Of Henle Flashcards
How much fluid leaves the proximal tubule?
300mOsmoles/l
What is the function of the loop of henle?
To produce concentrated urine in times of water deficiency
What is the maximum concentration of urine that can be produced by the human kidney?
1200-1400mOsmoles/l
What concentration do urea, sulphate, phosphate and other waste products need to be excreted at?
600mOsmoles which means a minimum 500ml of water needs to be lost
Why are the kidneys able to produce urine of varying concentration?
The loops of henle of juxtamedullary nephrons act as counter-current multiplies
What is the physiology behind the counter-current multipliers?
Uses energy to create an osmotic gradient which allows for the re-absorption of water from tubular fluid and this permits production of concentrated urine
What can permeate the descending limb?
H2O but not NaCl
What cannot permeate the ascending limb?
H2O
What is the mechanism behind the loop of henle?
Loop of henle is filled with stationary isosmotic fluid
NaCl is removed from ascending limb –> interstitium. Osmolarity increases in interstitium but decreases in tubule
Descending limb is exposed to greater osmolarity of insterstitum and h2o moves out to restore equilibrium
Fluid moves in at proximal tube and leaves at distal tube. NaCl is actively removed
Insterstitium becomes more concentrated
What occurs when frusemide is used?
Kidneys can only produce isotonic urine
What are the functions of the vasa recta?
Provide o2 for medulla, removes volume from interstitium ~36l/day
What occurs if the Na/K+ATPase activity in the loop of henle decreases?
Concentrated urine is produced
