What are bones made of? Are the bones living or non-living? Give reason.

1. Bone is a strong, hollow, hard and non-flexible connective tissue.
2. It is hard, greyish-white tissue and are made of two-thirds of inorganic substances which includes minerals such as phosphorus, calcium, carbonates etc. while one-thirds of it is composed of organic substances.
3. The outer surface of the bone is known as periosteum which is a thin, dense membrane which consists of an outer fibrous and inner cellular layer, blood vessels and nerves which nourish the bone.
4. The next layer is made up of compact bone. This part is highly calcified. It is extremely rigid and hard connective tissue which causes the bone to appear as smooth, solid and white.
5. The middle layer is composed of bone cells known as osteocytes which are arranged as concentric rings which are implanted in a hard matrix composed of collagen fibre and mineral deposits.
6. The innermost hollow cavity of long bones contains bone marrow responsible for synthesizing blood cells.
7. Bones are living tissues as long as they are located in the body of a living person. However, when they are taken out of the body, their cells die and the bones are then said to be dead.