Growth & Formation of Bone
The process of bone formation is called ossification. It occurs on hyaline cartilage models or fibrous membranes. Long bone growth involves 2 major phases.
- Osteoblasts (bone forming cells) cover hyaline cartilage model, hardening it by depositing calcium salts. By birth, most cartilage is converted to bone except for two regions in a long bone: the articular cartilages and the epiphyseal plates. In these locations new cartilages is continuously being replace.
- Enclosed cartilage is digested away, leaving behind the medullary cavity
Bone continues to grow through puberty. It is controlled by such hormones as growth hormone (GH). Epiphyseal plates are converted to bone during adolescence, at which time bone growth in length ends. Bones continue to remodel throughout life in response to pull of gravity on skeleton, pull of muscles on skeleton and blood calcium levels. Parathyroid Hormone is released when blood calcium levels are low and activate osteoclasts (bone-destroying cells) to break down bone to release calcium ions into the blood.