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The first step in the process is the formation of bone spicules which eventually fuse with each other and become trabeculae. The periosteum is formed and bone growth continues at the surface of trabeculae. Much like spicules, the increasing growth of trabeculae result in interconnection and this network is called woven bone.
The formation of bone is called ossification. During the fetal stage of development this occurs by two processes: intramembranous ossification and endochondral ossification. [42] Intramembranous ossification involves the formation of bone from connective tissue whereas endochondral ossification involves the formation of bone from cartilage.
The three main mechanisms by which osteoporosis develops are an inadequate peak bone mass (the skeleton develops insufficient mass and strength during growth), excessive bone resorption, and inadequate formation of new bone during remodeling, likely due to mesenchymal stem cells biasing away from the osteoblast and toward the marrow adipocyte ...
The number of vertebrae in a region can vary but overall the number remains the same. In a human spinal column, there are normally 33 vertebrae. [3] The upper 24 pre-sacral vertebrae are articulating and separated from each other by intervertebral discs, and the lower nine are fused in adults, five in the sacrum and four in the coccyx, or tailbone.
Osteoarthritis (OA) is a type of degenerative joint disease that results from breakdown of joint cartilage and underlying bone. [5] [6] It is believed to be the fourth leading cause of disability in the world, affecting 1 in 7 adults in the United States alone. [7]
This decreases bone formation, and is not a problem when a person has healthy bones. [126] It is thought, though, that decreasing the concentration of sclerostin in the body may lead to the formation of more bone, and that is the premise as to why monoclonal antibodies that reduce the concentrations of naturally occurring sclerostin may help ...
The organic part of bone is about 20% of the dry weight, and counts in, other than osteopontin, collagen type I, osteocalcin, osteonectin, and alkaline phosphatase. Collagen type I counts for 90% of the protein mass. The inorganic part of bone is the mineral hydroxyapatite, Ca 10 (PO 4) 6 (OH) 2.
As calcium is required for bone development, many bone diseases can be traced to the organic matrix or the hydroxyapatite in molecular structure or organization of bone. Osteoporosis is a reduction in mineral content of bone per unit volume, and can be treated by supplementation of calcium, vitamin D, and bisphosphonates .