Calcium Flashcards
What is the normal serum level of PTH?
50-60 pg/ml
What is normal serum calcium level?
8-10 mg/dl
What percent of serum calcium is bound? To what?
46-50% is bound to albumin
Where is the calcium sensing receptor?
Basolateral side on the TAL
What does the calcium sensing receptor do?
It binds free (ionized) calcium. If bound, it alters proteins in the paracellular space called claudins which prevent calcium ions from coming through. If unbound, it upregulates K+, Na+, and Ca+ to travel through the paracellular space.
How is calcium resorbed in the Distal Convoluted Tubule?
TRPV5 channel on the apical membrane.
Where in the nephron is the TRPV5 channel located?
Distal Convoluted Tubule
Where is calbindin located and what does it do?
It shuttles calcium from the TRPV5 channel across the intracellular space in the distal convoluted tubule.
What shuttles calcium across the intracellular space in the distal convoluted tubule?
calbindin
How does calcium get out of the distal convoluted tubule?
Calcium ATPase and Calcium/sodium anti-porter Na:Ca = 3:1
Where is the calcium/sodium antiporter located? What is the exchange rate?
the basolateral side of the distal convoluted tubule; 3 Na : 1 Ca
What does PTH do in Kidney? [4]
Where does it work in Kidney? [2]
Increses Vit D production in proximal tubule
Increased proximal tubule uptake of calcium.
Stimulates Phosphorus excretion.
Upregulates TRPV5 intake of Ca on apical side and extrusion on basolateral side. Distal convoluted tubule
How does the parathyroid gland work?
It senses ionized calcium. When receptors are bound, PTH production is reduced. When receptors are not bound with calcium, PTH is release.
What does PTH do to bone?
PTH causes bone to dump calcium stores. If it is active long enough, it will cause bone resorption. Kidney patients have a high fracture risk for this reason.
If bone is resorbed, what is released with calcium?
phosphorus
