NUTR 4320 Lecture Notes - Lecture 20: Bone Resorption, Leukemia Inhibitory Factor, Bone Remodeling
Document Summary
Majority of the pth receptor on the osteoblasts signal it to release factors. Osteoclasts are multinucleated cells of hematopoietic cell origin involved in bone resorption. Bone resorption generated by the fusion of intracytoplasmic acidifying vesicles with the plasma membrane. Ruffled border essential to resorption (connection with exocytosis from bone cell macrophages it increases surface area for resorption), but mechanism not defined. Osteoclasts are removed from the surface of the bone and leave room for osteoblasts to fix the surface and formulate new bone. Bone formation is a slow process (blood vasculature pth, gh, igf1) Remodelling initiated when osteocytes sense strain or damage to the bone matrix. Quiescence activation resorption formation mineralisation quiescence. Osteocytes (matrix) are induced to undergo apoptosis and release factors that recruit osteoclasts and initiate osteoblasts. Vascular endothelial growth factor (vegf) stimulate migration & extravasation of osteoclast precursor to bone surface. Rankl is found on osteocyte and osteoblast membrane and activates osteoclasts.