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%
How does PO4 effect pH of urine?
buffer H+ secreted from A intercalated cells in the CCD
what inhibits PO4 reabsorption?
PTH
True or False. PTH increases plasma Ca and decreases plasma PO4.
true
True or false. Plasma phosphates affect PTH secretion from the parathyroid gland
False. PO4 do not affect PTH secretion. plasma Ca DOES
