Loop of Henle Flashcards
What is the osmolarity in the proximal tubule?
300mmoles
Whats is the osmolarity at the ascending loop?
100mmoles
What is the osmolarity of plasma?
300 mmoles
Where are the distal & proximal tubules found?
Cortex
What is the mechanism by which urine is concentrated?
Countercurrent multiplier
What is the maximum concentration of urine?
1200-1400mOsm
What is the minimum obligatory water loss?
500mls
What is the minimum concentration of urine?
30-50mOsm
What is actively co-transported out the tubule at the ascending limb?
NaCl
What is the ascending limb impermeable to?
Water
What is the descending limb permeable to?
Water
Where does water in the interstitium move to?
Vasa recta
The tubule is progressively____ as it moves down the descending limb
concentrated
The tubule is progressively _____ as it moves up the ascending limb
diluted
In the LoH, what is the horizontal gradient observed between the ascending limb & interstium?
200 msom
What is the vertical gradient in the interstiium?
300>1200mOsm
What occurs at the collecting duct? Regulated by?
Water reabsorption
ADH
In the presence of frusemide, what is the osmolarity of urine?
300mOsm
Isotonic
What do diuretics produce?
Large volume of dilute urine
What does the countercurrent multiplier achieve?
Generates a concentration gradient in the medullary intersistium
What is the function of the vasa recta?
Delivers O2 to the medulla
Removes volume from the interstitium
What is the flow rate in the vasa recta like?
Low, allows the equilibrium of interstitium
Where is ADH produced?
Posterior pituitary
What does ADH do at the collecting duct?
Increases water reabsorption
