Largest store of bodily calcium?
Contained within the skeleton
Calcium levels are primarily controlled by? & small roles?
Parathyroid hormone (PTH), vitamin D and calcitonin.
Both growth hormone and thyroxine also play a small role in calcium metabolism.
Actions of PTH? (7)
calcium levels and decrease phosphate levels
- Increases bone resorption
- Immediate action on osteoblasts to increase ca2+ in extracellular fluid
- Osteoblasts produce a protein signaling molecule that
osteoclasts which cause bone resorption
- Increases renal tubular reabsorption of calcium
- Increases synthesis of 1,25(OH)2D (
form of vitamin D) in the kidney which increases bowel absorption of Ca2+
- Decreases renal phosphate reabsorption
Actions of 1,25-dihydroxycholecalciferol ((the active form of vitamin D)?
- Increases plasma calcium and plasma phosphate
- Increases renal tubular reabsorption and gut absorption of calcium
- Increases osteoclastic activity at high levels and osteoblasts at low levels
- Increases renal phosphate reabsorption
- Secreted by C cells of
- Inhibits intestinal calcium absorption
- Inhibits osteoclast activity
- Inhibits renal tubular absorption of calcium