1/10
Looks like no tags are added yet.
Name | Mastery | Learn | Test | Matching | Spaced |
---|
No study sessions yet.
to maintain water balance or homeostasis, kidneys need to be able to secrete urine that is sometimes? How when water only moves by osmosis?
less concentrated (dilute, <300_)
more concentrated than plasma (conc. > 300)
countercurrent multiplication
goals of countercurrent multiplication
compared to plasma:
dilute tubular fluid
To make medullary intersitial fluid to be concentrated
because of the way loop of henle is designed:
1st end result: exrete dilute:
at the turn, filtrate is concentrated
more NaCl leaves than H2O
2nd end result: excrete concentrated urine
Body can excrete either dilute or concentrated urine, because of the ?
countercurrent mechanism: Loop of henle
dilutes tubular fluid
concentrates medullary intersitiam (concentrated urine)
Variable permeability of collecting duct to water
__ controls the water permeability of collecting duct: how?
antidiuretic hormone
collecting duct is impermeable to water: dilute urine
NO ADH → no channels on luminal membrane (#2)
Collecting duct is permeable → concentrated urine:
ADH: Aquaporin 2 = aquaporinin channel on luminal membrane
ADH activation
adh binds to V2 receptor on basolateral side of cell
Aquaporin 2 on luminal side is activated
because of the countercurrent mechanism:
medullary intersitium is increasingly concentrated
With ADH and water channels, water continues to be reabsorbed as ?
filtrate goes down collecting duct, due to the medullary interstitium increasinly concentrated
With no ADH: osmolairty is ?
max ADH + max osmolarity is ?
50, no aquaporins, very hydrated
1200, dehydrated, many aquaporins
in presence of ADH, what will happen to urine?
smaller volume of more concentrated uirne
normal 24 hour urine osmolarity average
500-800