Loop of Henle Flashcards
what is the major site of reabsorption?
the proximal tubule
what is the maximum concentration of urine we can produce (comparative to plasma)?
> 1200-1400 mOsmoles/l
> 4 times more concentrated
why must there always be a minimum obligatory loss of 500mls of H20?
since waste products such as urea, sulphate and phosphate must be excreted
what act as counter current multipliers?
the loops of henle of the juxta medullary nephrons
describe how the ascending limb of the loop of henle creates a counter current multiplier
> actively transports Na+ and Cl- out of the lumen into the interstitium
impermeable to H20
describe the characteristics of the descending loop of henle that creates a counter current multipliter
> freely permeable to H20
> relatively impermeable to NaCl
True or false:
active removal of NaCl from the ascending limb increases osmolarity in the interstitium and decreases osmolarity of the tubule
true
why does H20 move out of the descending limb in the loop of henle?
to equate the osmolarity caused by the transport of NaCl into the interstitium
what happens to H20 after it has moved out of the descending limb?
it is reabsorbed into the vasa recta by the high osmotic pressure and tissue pressure
true or false:
the greater the concentration of the descending limb the lesser the concentration of the interstitium
false:
the greater the concentration of the descending limb the greater the concentration of the interstitium
what is the gradient between the ascending limb and the interstitium at any horizontal level?
200mOmsmols
what is the key step in the counter current multiplier system?
active transport of NaCl out of the ascending limb
what is the effect of the active transport of NaCl being abolished?
only isotonic urine is produced
true or false:
fluid entering the distal tubule is more dilute than t he plasma
true
how do the vasa recta participate in counter current mechanisms?
by acting as counter current exchangers:
> don’t disturb the interstitial gradient
> remove volume
