Integration of Ca and P Flashcards
What type of Calcium is sensed and regulated?
Ionized
Which vitamin regulates Ca absorption
Vitamin D
Function of PTH
Increase Blood Ca
Action of PTH on bone
Increase Bone Resorption
Action of PTH on the kidney
Increased distal tubular Ca re-absorption
Decreased proximal tubular Ca re-absorption
Increased production of 1,25(OH)2D3
Action of PTH on intestines
Increased absorption of Ca and Pi via increased production of 1,25(OH)2D3
Main Receptor for PTH release
Ca-SR on parathyroid gland
nb: responds to extracellular Ca2+
Major step in activation of vitamin D
1-alpha hydroxylation of 25(OH)D3 in the kidney
1a Hydroxylase a.k.a CYP27B1
Mechanism of innactivation of 1,25(OH)2D3 and 25(OH)D3?
Hydroxylation at the 24th position
Name of Vitamin D deficiency in children and adults?
Rickets = Children Osteomalacia = Adults
Where is calcitonin produced?
C cells in thyroid (Parafollicular area)
Inhibits osteoclastic bone reabsorption
What is FGF-23? What cell produces it?
Phosphatonin, decreases Pi levels in the blood
Inhibits renal 1alpha hydroxylase
Produced by osteocytes
Chaperone of Ca within the cell?
Calbindin
Events after 1,25(OH)2D3 binds to Vitamin D receptor?
Calbindin increases
Ca channels increase
Ca pump on serum side increases
Most absorption of Ca occurs at which part of the kidney and by what mechanism?
Proximal Tubule by passive transport (~70%)
