Bone

Definition
Bone is a very strong, solid, rigid, highly vascular, mine ised and non tissue. Bone cells (osteocytes) are embedded in a hard matrix that is made up of ossein protein and tible connective various types of inorganic mineral salts such as phosphates and carbonates of calcium and magnesium. The matrix of the bone is in the form of thin concentric layers called lamellae, which are laid down around narrow channels known as Haversian canals that run parallel to the length of the bone. Haversian system is the structural unit of the mammalian long bone. Haversian canal contains blood vessels, nerve fibres and some bone cells. These are interconnected by transverse channels called Volkmann's canals. The individual spaces in which osteocytes are present are called lacunae. One osteocyte is present in one lacuna, which leads into fine radiating channels, called canaliculi. With the help of canaliculi one osteocyte is in contact with other osteocytes.

Function
Bones form the endoskeleton in human beings and other vertebrates, except the sharks and some other animals, where the skeleton is made up of cartilage.

Bones form the frame work of the body.

They provide shape to the body.

They protect vital organs of the body such as brain, lungs, heart, kidneys etc.

They serve as storage site of calcium, phosphorus and other minerals.

Bones provide surface for attachment to many muscles.

Bones form various types of joints which take part in different body movements including locomotion.