Renal: K, Ca, PO4 balance Flashcards
what % is total body K intracellur? extracellur?
intra - 98%
extra - 2%
(total body K = 3500 mEq 136.5 g)
where does the fine tuning of K excretion take place?
CCD secretion
where is K passively absorbed in the nephron?
PT via paracellular movement
how is K secreted in the collecting ducts?
basolateral Na/K-ATPase and apical K channels in principal cells
How is K reabsorbed in collecting ducts?
H/K-ATPase in type A intercalated cells
True or false. High plasma K levels stimulate aldosterone secretion from the adrenal cortex.
true
as well as Ang II (due to low plasma vol.)
how does the high plasma K cause the adrenal cortex to release aldosterone?
depolarized the aldosterone secreting cells which cause the release of aldosterone into the blood
what is total plasma Ca?
approx 2.5 mM
What % of Ca is free ionized? Bound to proteins? Ca citrate or phosphate?
a. ionized - 45%
b. bound - 40%
c. citrate/phospate - 15%
where is filtered Ca reabsorbed in the nephron?
passively reabsorbed in : PT 70% TAL 20 % DT 6-8 % CCD 2 %
how much Ca is reabsorbed?
98% (slide says Ca is NOT secreted)
where does fine tuning of Ca reabsorption take place?
DT stimulated by parathyroid hormone (PTH)
what is true of PTH?
- released from parathyroid gland
- low plasma Ca stimulates PTH secrection
- stimulates calcitriol synthesis
- PTH increases plasma Ca by stimulating Ca reabsorption in kidneys, absorption in intestine stimulated via calcitriol, resorption Ibreakdown) from bone to blood
what is total plasma phosphate levels?
0.8 - 1.5 mM
How much is PO4 is freely filtered?
90 - 95%
