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45 Cards in this Set
- Front
- Back
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From which cells do osteoblasts arise?
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Undifferentiated mesenchymal stem cells (MSCs)
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What seven growth factors influence osteoblast differentiation?
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Interleukins (ILs)
Insulin-like growth factor (lGF-l) Platelet-derived growth factor (PDGF) Bone morphogenic proteins (BMPs) Transforming growth factorB (TGF-3) Osterix Runx 2 (formerly Cbfa I) |
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What is the function of IGF?
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Osteosynthesis
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Through what intracellular signaling pathway does it work?
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Tyrosine kinase
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What is the function of PDGF?
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Chemotaxis
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Through what intracellular signaling pathway does it work?
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Tyrosine kinase
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What is the function of BMP?
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Stimulates mesenchymal cell differentiation
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Through what intracellular signaling pathway does it work?
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Serine/threonine kinase through SMAD proteins
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ls BMP osteoinductive or osteoconductive?
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Osteoinductive
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TGF-B stimulates mesenchymal cells to
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Type II collagen
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produce what two substances?
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Proteoglycans
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TGF-B also indirectly stimulates osteoblasts to produce what?
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Type I collagen
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Through what intracellular signaling pathway does it work?
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Serine/threonine kinase
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What four substances do osteoblasts produce?
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Alkaline phosphate
Type I collagen Osteocalcin RANK ligand |
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Osteoblasts respond directly to what five factors?
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Parathyroid hormone (PTH)
Glucocorticoids Prostaglandins 1,25-vitamin D Estrogen |
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Which two of these favor osteogenesis?
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1,25-vitamin D
Estrogen |
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Which three favor resorption?
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PTH (resorption releases calcium)
Glucocorticoids Prostaglandins |
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What two factors upregulate adenylate cyclase at the cellular level?
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PTH
Prostaglandins |
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What factor downregulates adenylate cyclase?
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Estrogen
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What factor also decreases calcium absorption at the level of the gut?
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Glucocorticoids
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From what cells do osteoclasts arise?
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Monocyte progenitors
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How do osteoclasts bind to the surface of bone?
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With integrins (vibronectin)
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Where does resorption occur?
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Howship's lacunae
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What are the two products of osteoclasts?
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Hydrogen ions (through carboni canhydrase)
Tartrate resistant acid phosphatase |
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What do osteoclasts respond directly to?
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Calcitonin
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What is the effect of calcitonin on the osteoclast?
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Inhibits osteoclast function
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What is the effect of lL-1?
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Stimulates osteoclast function
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What is the effect of lL—10?
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Inhibits osteoclast function
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What is the effect of lL-11?
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Increases production of RANK ligand
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What is the function of RANK ligand?
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Links osteoblast and osteoclast function
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What cell contains RANK ligand?
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Osteoblast
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How does RANK ligand work?
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Binds to and stimulates osteoclasts
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What cofactor is required?
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Macrophage colony-stimulating factor (M-CSF)
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What inhibits the RANK stimulation osteoclasts?
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Osteoprotegerin
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How?
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Blocks RANK binding to the osteoclast, competitive inhibition
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If considering estrogen replacement therapy, when should it be started for
maximal benefit? |
Within 5 to 10 years of menopause
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Generally speaking, how does estrogen work?
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Decreases both bony resorption and formation
But resorption is decreased much more than formation |
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What are two pharmacologic alternatives to estrogen therapy?
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Alendronate
Raloxifene |
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What are osteocytes stimulated by?
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Calcitonin
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What are osteocytes inhibited by?
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PTH
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How does mechanical stimulation work?
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Increases prostaglandin E2 production (stimulus)
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How are osteons connected to one another?
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By hawersian canals
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What are the extensive networks of osteonal processes that allow communication?
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Canajiculi
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What is the outer osteonal border called?
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Cement line
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What lies in between osteons?
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Interstitial lamellae
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