Medical Sciences 3999A/B/Y Lecture Notes - Lecture 14: Bone Sialoprotein, Bone Resorption, Alkaline Phosphatase
14 Feb 2020
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Document Summary
Osteoblasts: epithelial-like cell monolayer (cuboidal or columnar) covering sites of active bone formation. Contact to neighbouring osteoblasts and osteocytes via gap junctions. Calcification of osteoid initiated as it moves into the matrix --> cross-linking. Osteocalcin: protein with high binding affinity for hydroxyapatite; required for mineralization. Osteopontin: mediate formation of sealing zones of osteoclasts. Bone sialoprotein: mediate binding of osteoblasts to ecm through integrins. Osteocytes: formation occurs following differentiation of osteoblasts and subsequent encasing of the cell by self-synthesized osteoid matrix. Lacunae and canaliculi form around the osteocyte and its cytoplasmic processes. Flat, oval or lenticular cells with less rer and golgi. Osteocytes have reduced synthetic activity and are not capable of mitotic division. However, they are actively involved in the maintenance of bony matrix. Binding stimulates secretion of collagenous and non-collagenous proteins. Growth hormones brings igf-1 which stimulates osteoblasts to facilitate bone mineralization. Rank-l ligands bind osteoclasts to stimulate osteoclastogenesis (in response to pth binding)
