Calcium and phosphate metabolism Flashcards
What cells release PTH?
Chief cells
What triggers PTH release?
Low serum calcium
What are the actions of PTH?
Increases calcium absorption in the intestine by increasing calcitriol, increasing bone resorption, decreases phosphate reabsorption, increases calcium reabsorption
What is the main way of controlling calcium levels?
PTH
What cells release calcitonin?
Parafollicular cells
What triggers release of calcitonin?
High serum calcium
What is the action of calcitonin?
Decreases bone resorption to decrease serum calcium
What triggers FGF-23 release?
High serum phosphate, high serum PTH, high serum calcitriol, dietary phosphate loading
What cells release FGF-23?
Osteocytes
What is the action of FGF-23?
Decreasing 1-alpha-hydroxylation of vitamin D which decreases gut absorption of phosphate and decreases expression of Na transporter in the renal tubule which increases renal phosphate excretion
What is klotho transmembrane protein associated with?
FGF-23
What is the precursor to vitamin D?
7-Dehydrocholesterol
What is calcitriol?
Activated vitamin D