Flashcards in 17. Cell biology of bone Deck (21)
Osteoblasts action ich
build bone by secereting collafen and catalyzing mineralization
bone mineralization is process in which
crystals of calcium phosphate are produced and laid down within the bone's fibrous matrix
Osteoblasts - differentiate from
mesenchymal stem cells
Osteoblasts - differentiate from ( where )
mesenchymal stem cells in periosteum
dissolce bone by secreting acid and collagenases
osteoclas - differentiate from
parathyroid hormone action on bone
- low intermittent levels --> anabolic effects ( bulilding bone ) on osteoblasts and osteoclasts ( indirect)
-chronically increased PTH ( 1ry hyperparath) --> catabolic effect ( osteitis fibrosa cystica)
estrogen action on bone
1. inhibits apoptosis in osteoblasts
2. induce apoptosis in osteoclasts
bone - estrogen deficiency -->
excess cycles of remodelling --> bone resorption leads to osteoporosis
bone - multinucleated cells
bone - monocytes and macrophages are differentiate to
bone - mesenchymal stem cells are differentiate to
• What is the source of osteoblasts, and how do they build bone?
Mesenchymal stem cells in the periosteum differentiate into osteoblasts, which secrete collagen and catalyze mineralization
• What secretions of osteoclasts effectively dissolve bone?
Acids and collagenases
• A doctor gives his rival a drug so that he can no longer break down old bone cells. Which enzyme does this drug most likely inhibit?
Collagenase, as osteoclasts release acids and collagenases to dissolve old bone
• The cells that dissolve bone are derived from what precursor cells?
Osteoclasts are derived from monocytes and macrophages
• How is parathyroid hormone involved in normal bone physiology?
At low, intermittent levels, it exerts anabolic (bone-building) effects by activating osteoblasts directly and osteoclasts indirectly
• A patient has osteitis fibrosa cystica. Which hormone is likely chronically elevated in him?
PTH, leading to excess bone catabolism
• How does estrogen exert its effects on bone?
It inhibits apoptosis in bone-forming osteoblasts and induces apoptosis in bone-resorbing osteoclasts