Kidney- water balance Flashcards
In order to maintain proper fluid balance, the kidney has the ability to excrete either a ___ urine to eliminate excess water, or a ____ urine to conserve water
dilute
concentrated
Antidiuretic hormone and aldosterone act on the kidney to regulate blood ____ and increase blood ____
osmolarity
volume
Natriuretic hormones (ANP, BNP, …) act on the kidney to stimulate ____ and decrease blood volume
diuresis
volume
3 ways we gain water:
drinking
food
metabolism
four ways we lose water:
urination
defecation
respiration
sweat
([Na+] + [K+]) − ([Cl−] + [HCO3−])
this represents:____
Anion gap
__% of Body weight is water
~___ L/day of water filtered (48 gallons!)
Water must be ___ to prevent dehydration
60
180
reabsorbed
____% of water is reabsorbed by PT
Hyperosmotic interstitial fluid (___ mOsm/L)
Hyposmotic tubular lumen (___ mOsm/L)
Osmotic pressure difference drives water to be ____
65-80
293
287
reabsorbed
Water is reabsorbed by ____ and mostly follows sodium
osmosis
PCT: ~__% H2O reabsorbed
Loop (descending limb): ~__% H2O reabsorbed
DCT: ~____% H2O reabsorbed
Late DCT & collecting duct: ~____% H2O reabsorbed (stimulated by ___) (reabsorbed with the Na+ & Cl- stimulated by ___)
65 15 10-15 5-10 ADH aldosterone
___ hydrostatic pressure and ___ oncotic pressure in peritubular capillaries favors water reabsorption
Low
high
The Loop of Henle:
Consists of a thin descending limb, permeable to ___
Sharp turn is permeable to ___ (recycles urea)
Thick ascending limb has ___ permeability to water and does Transport of _____
water
urea
Low
Na 2Cl K
~___% of water is reabsorbed by Loop
15
Countercurrent mechanism:
Descending loop of Henle
Water ____
↑____ in tubular lumen
Ascending loop of Henle
↓___ cytosolic (due to Na+-K+-pump)
Na+, K+, 2 Cl- (Symport)
Other Cations - ___++, ___++, etc.
Vasa recta – carries __ and___ into medulla and water out to the cortical veins
reabsorption [NaCl] [Na] Mg++, Ca++ Na+ & Cl-
active salt transport out of the water-impermeant thick ascending limb established a ____ gradient of about 200 mOsm/kg H2O between the tubular fluid and the medullary ISF
horizontal
The increased salt and osmotic concentration of the medullary ISF causes ___ to move into the descending limb and ___ to move out.
Both increase the osmotic concentration of tubular fluid
The small horizontal gradient is multiplied longitudinally by the ____ flow arrangement
salt
water
countercurrent
In the _____ vasa recta, blood coming down into the medulla from the cortex comes into contact with the concentration medullary ISF. ___ diffuses from that ISF into the blood increasing plasma concentration.
descending
Salt
In the ___ vasa recta, concentrated blood flowing up towards the cortex from the papilla loses ___ to the more dilute medullary ISF. Thus the salt, reabsorbed from the loop of henle, is trapped and recycled within the medulla by countercurrent flow of blood in the vasa recta.
ascending
salt
In the descending vasa recta, the dilute blood thats flowing into the medulla loses __ to the concentrated medullary ISF
water
In the Ascending vasa recta, the concentrated blood flowing from the tip of the papilla towards the cortex gains ____ from the medullary ISF.
Thus ____ tends to short-circuit from the descending to the ascending vasa recta.
This helps preserve the concentration of the medullary ISF
water
water
the descending limb is ___ permeable and has no ___ pump
water
Na
the ascending limb is not ___ impermeable but contains ___ pump
water
Na
___ and ___ are reabsorbed from filtrate in the ascending limb
Reabsorption of salt without water in the ascending limb makes the tubule fluid ___
Na+ and Cl-
dilute
the vasa recta & descending limb carry the salt back into the medulla to create and maintain a ___ osmotic pressure of the medulla’s interstitial fluid
high
