Skeleton includes bones and cartilages. It forms the main supporting framework of the body, and is primarily designed for a more effective production of movements by the attached muscles.
Bones
Synonyms
1 Os (Latin); 2. Osteon (Greek).
Bone is a connective tissue , impregnated with calcium salts. Connective tissue forms one third of the bone and calcium salt about two thirds The inorganic calcium salts are mainly calcium phosphate, partly calcium carbonate, and traces of other salts. These make it hard and rigid, which can afford resistance to compressive forces of weight-bearing and impact forces of jumping. The organic connective tissue makes it tough and resilient , which can afford resistance to tensile forces.
In strength, bone is comparable to iron and steel.
Despite its hardness and high calcium content the bone is very much living tissue. It is highly vascular, with a constant turn-over of its calcium content. It shows a characteristic pattern of growth. It is subject to disease and heals after a fracture. It has greater regenerative power than any other tissue of the body, except blood.
It can mould itself according to changes in stress and strain it bears, it shows disuse atrophy and overuse hypertrophy.
Functions of bones
1 Bones give shape and support to the body, and resist all forms of stress.
2 They provide surface for the attachment of muscles, tendons, ligaments, etc.
3 They serve as levers for muscular actions.
4 The skull, vertebral column and thoracic cage protect brain, spinal cord and thoracic viscera, respectively.
5. Bone marrow manufactures blood cells.
6 Bones store 97% of the body calcium and phosphorus.
7 Bone marrow contains reticulo-endothelial cells which are phagocytic in nature and take part in immune response of the body.
Text adapted from: Human Anatomy by BD Chaurasia
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