All of the following are true about osteoclasts except
Ans b: (PTH acts directly onosleoclasts) Ref: Harrisson 17th edition p 2367OsteoblastsSynthesize & secrete matrixMesenchymal originSeen on surface of new boneOsteoblast derived matrix when mineralized is osteocyteMineralisation depends on osteoblast derived ALP (marker of blast)Controls1. CBFA1 (Runx 2)- Transcription factor regulating osteoblast function. Heterozygous inactivating mutation Icleidocranial dysplasia2 Indian hedgehog3 Wnt family members. Deficiency of Wnt family co receptor LRP 5- osteoporosis4 TGF beta, FGFs 2 & 18, PDGF, IGF 1 $ 25 PTH & l,25 dihydroxyD activate receptors expressed by osteoblastOsteoclastResorption of boneMultinucleated giant cell (2-5nuclei) from monocyte/macrophage lineage.Macrophage colony stimulating factors (M-CSF) plays a crucial role Osteoblasts control osteoclast activityRANK ligand expressed over osteoblast progenitor & stromal cells bind to RANK receptor on osteoclast progenitor to stimulate osteoclast differentiation.Osteoprotegerin binds to RANK ligand and inhibit osteoclast differentiation1L 18 is also an inhibitor of osteoclast differentiationPTH & 1,25 dihydroxyD increases osteoclast number & activityEstrogen decreases osteoblast number and activity}Both indirectly through RANK L and M CSF.Calcitonin has direct inhibitory effect on osteoclast formation
Derived from monocytes
PTH acts directly on osteoclasts
Associated with bone demineralisation
Can phagocytose foreign bodies
Osteology