Reg of K+, Ca2+, PO4 (lec 15) Flashcards
(21 cards)
K+ important for excitability of nn and mm how?
K+ gradient controls rest MP
Levels of K+ in ECF dependent on?
total K+ in body (ingested/excreted)
distribution b/w ECF/ICF
K+ controlled by what hormones? (3)
1) Epi
2) Insulin
3) Aldosterone
Epi control of K+?
Muscle and Liver:
⍺1 shifts K+ out of cell (hyperK+)
β2 shifts K+ into cells (hyopK+)
Insulin control of K+?
↑ uptake into cells via Na+/K+ATPase
Aldosterone control of K+?
↑ uptake into tubules
↑ excretion
stim Na+/K+ATPase
Acid/Base control of K+?
Acid moves K+ out of cells
Base moves K+ into cells
Transport of K+ in PCT/LOH affected by [K+] in body how?
Δ in [K+] does not Δ transport
87% of K+ reab in PCT/LOH
K+ regulation happens where?
DCT/CD
12% of K+ reab here
Response to low K+ intake?
↓ excretion
K+ reab in distal nephron mechanism?
K+/H+ATPase from lumen into cell
Passive diffus out of cell into blood
Response to high K+ intake?
Aldosterone released -> K+ excreted
K+ excretion mechanism?
baso memb of Principle Cells, Na+/K+ATPase pulls K+ into cell from blood
K+ diffuse thru luminal memb
Ca2+ reabsorbed by nephron where?
everywhere except descending LOH
What % of plasma CA2+ if filtered by kidney?
60% (U) 7.5 mg/min
What % of filtered Ca2+ is excreted in urine?
1%
Ca2+ reab in DCT mechanism?
Ca2+ channels from lumen into cell
thru baso memb via Ca2+ATPase and Na+/Ca2+ exchange
Ca2+ uptake in DCT stimulated by?
Mediated by?
PTH
cAMP
What % of plasma PO4 filtered by kidney?
Where?
95%
glomerulus
What % of PO4 reabsorbed by kidney?
Where?
Reab inhibited by?
85% (15% excreted in urine)
PCT
PTH
PO4 important for urine how?
buffer in acid-base balance
