Urine concentration and dilution Flashcards
What is a hypotonic solution?
Low osmolality
What happens to water in the collecting duct?
Water leaves due to an increase in osmolality- concentrates urine
What inhibits AVP release?
Increase stretch in atria- baroreceptors stimulation
Where is AVP made and released?
Made-paraventricular nucleus of hypothalmaus
Released- posterior pituatary
What does AVP cause?
Vasoconstriction and kidney AQP
What does KO AQP1 show?
Problems with urine concentration but largely healthy as not contributing full amount to counter current multiplication
Through what channel does water move out in the thin descending limb?
AQP1
What does the thin ascending limb do?
water impermeable, NaCl out and urea in
What does the thick ascending limb do?
Apical- NKCC2 ROMK
Basolateral - Na/k pump (drives NKCC2), k out, CLCK regulated by Barttin B subunit
Paracellular reabsorption of Calcium
What are the symptoms of Bartters syndrome?
Salt wasting and polyuria, hypokalaemia, metabolic alkalosis, hypercalciuria, nephrocalcinosis
Principle cell
Apical- ENaC ROMK AQP2
Basolateral- Na/K pump, K out, AQP3+4
What determines water reabsorption?
AQP2
What part of the collecting duct is permeable to urea?
Inner medulla
What does KO A1/A3 show in mice with and without water?
With- half the osmolality in urine. Without water- quarter the osmolality in urine
