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.
Cancellous bone resembles latticework and is spongy.
A system of blood vessels supplies the bones with needed nutrition. Bones serve as storehouses for minerals and fats. Approximately a quarter of a bone's weight is fluid. Minerals make up the remaining weight along with other nutrients. The semi soft center of the bone contains marrow.