Lecture 24 Flashcards
(19 cards)
What is the Plasma calcium concentration?
2.4 mM (Half found to proteins)
What is the concentration of Free Plasma Concentration?
1.2 mM
What is the Calcium concentration inside the cells?
10-7 M (At rest)
How is Calcium pumped out?
By active transport and by using sodium electrochemical gradient
What is the function of Osteoblasts?
- Synthesize and secrete collagen fibres
- Promote calcium phosphate deposition
What is the function of Osteoclasts?
Cause bone to release calcium and phosphate from the non-exchangeable pool (99%)
What is the function of Osteocytes?
Exchange calcium phosphate between the exchangeable pool (1%) and extracellular fluid
List the 3 hormones important for Calcium balance
Parathyroid hormone
- Increases plasma calcium
Calcitriol
- Increases plasma calcium
Calcitonin
- Decreases plasma calcium
How is the Parathyroid hormone secreted?
By chief cells of the parathyroid glands as a preprohormone
- Cleaved in the liver and kidney
What happens with you remove Parathyroid glands?
Reduces plasma calcium by 50%
How is PTH secretion stimulated?
By decreased plasma calcium
How is PTH inhibited stimulated?
By increased plasma calcium
List some actions of PTH
- Increase Bone Ca2+ reabsorption
- Increase Intestine Ca2+ absorption
What is the function of Calcitriol/Vitamin D?
- Increases calcium absorption in small intestine: increases plasma calcium
- Increases bone resorption: increases plasma calcium
What does Vitamin D deficiency lead to?
Softening of bones
- Rickets in children
- Osteomalacia in adults
Where does the conversion happen?
Only where enzymes are expressed
What do C cells secrete?
Calcitonin
What is the function of Calcitonin?
Inhibits osteoclasts to reduce bone resorption and increases urinary calcium excretion to decrease plasma calcium
Where is Calcitonin secreted from?
C Cells (Parafollicular cells)
