Texts: Bone Tissue & Axial Skeleton LAB ACTIVITY 13: Cells of Bone Bone is produced, remodeled, and maintained by the activities of 3 cell types - osteoblasts, osteocytes, and osteoclasts. 1) Osteoblasts are produced in the bone marrow and function to produce "osteoid", then add calcium and other minerals to form the composite extracellular matrix of bone. 2) Osteocytes are osteoblasts that have become surrounded by the mineralized extracellular matrix. Although "trapped" within lacunae, these cells do not function in isolation. They have extensive dendritic processes that allow them to detect pressure & loading stresses on nearby bone and communicate with other cells within bone. New osteoblasts are produced by osteogenic stem cells (or osteoprogenitor cells) associated with the deep layers of the periosteum and the marrow. 3) Osteoclasts are produced by differentiation of white blood precursors into large, multinucleate cells that break down (resorb) bone. 0.3 Pts. 4) Low blood calcium triggers the release of parathyroid hormone (PTH) from cells of the parathyroid gland. PTH stimulates osteoclasts to resorb bone, thus releasing calcium from bone to enter the vasculature. The integrated control of osteoblasts, osteocytes, and osteoclasts is important for maintaining bone mass and for control of remodeling and healing processes in bone. Explain how braces straighten teeth. 0.2 Pts.

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