Renal concentrating mech Flashcards
offluidisfilteredinoneday
180L
of urine volume is excreted each day
0.5-1.5L
less than _____of filtered water is excreted as urine while _____is reabsorbed.
1%, 99.4%
_______water reabsorption in the Proximal tubules.
60-70%
15-20 % of water is reabsorbed in
the thin descending part of loop of henle & in the distal tubule + collecting ducts
60-70%ofwaterispassivelyre- absorbed following the osmotic gradient created by
sodiummmmm reabsorption
channels(intheproximal tubules at basolateral and apical membranes) facilitate water re- absorption.
aquaporin-1
fluid leaving the PCT issss ____tonic
iso
at the end of the medulla the osmality _____to_____
increases to 1200
osmolarity at the end of the medulla is aka
vertical osmotic gradient
osmolarity in the cortex
300
Inthindescendingpart;15-20%offiltered water is reabsorbed passively following the osmotic gradient of
medullary tissues
Fluid leaving Henles loop is
hypotonic
Thedistalandcollectingtubulesare
relatively impermeable to water except in
the presence of
ADH
ADH increases water permeability in the ____
prinicpal cells
The effect of ADH is mediated via
v2 receptors & cAMP
ADH acts by
inserting aquaporin-2
channels on the luminal membrane.
ADH wouldn’t work ifffff
the medulla aint hypertonic
Urine volume may reach 23 L/day with low concentration (≈ 50 mOsm/L).
absence of ADH
• The volume of urine may be as low as 500 ml/day with a maximum
concentration of 1200 mOsm/L.
presence of ADH
The factors that create and maintain the high osmotic gradient in renal medulla are
- countercurrent mechanism 2. low blood flow to medulla 3.urea recycling
state the two systems in the countercurrent mechanism
loop of henle, vasa recta
state the 3 princcples of the countercurrent system
parallel, in opposite direction, have very close association
Medulla recieves less than ______of renal blood flow to nourish the tissue
10%
All capilaries are freely permeable to
NaCl + H20
countercurrent exchange
passive exchange of salt and water between the two limbs of the vasa recta and the ISF.
______of Urea is re-absorbed in PCT ______of Urea is re-absorbed in DCT.
50%, 30%
