Bones are long, flat, short or irregularly shaped, and some are thicker than others. Bones are flexible during youth, eventually becoming rigid at maturity. If a bone is broken, collagen, which is manufactured by the body, mends the fracture. The new bone is then hardened through a process termed calcification.
Bone is a living organ comparable to the heart or kidneys.
It contains blood vessels and is nourished through circulation. If any bone or organ system is ignored or misused, it can decay and cause problems. Within bone are two compartments. The outer layer is termed cortical bone and the inner is cancellous bone. Microscopically, cortical bone looks like concentric rings.