Bone

Article By:

Findlay, David M. Department of Orthopaedics and Trauma, University of Adelaide, Adelaide, Australia.

Last reviewed:June 2021

DOI:https://doi.org/10.1036/1097-8542.090300

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• Bone, published 2014:Download PDF Get Adobe Acrobat Reader

The hard connective tissue that, together with cartilage, forms the skeleton of humans and other vertebrates. Bone (Fig. 1) is made of calcium phosphate crystals arranged on a protein scaffold and performs a variety of functions. For example, it has a structural and mechanical role, protects vital organs, provides a site for the production of blood cells, and serves as a reserve of calcium. Bone tissue is constantly renewing itself, and it has great capacity to respond to altered stresses and loads and to repair fractures. The formation and remodeling of bone are accomplished by the action of bone cells of the osteoblast (bone-forming cell) and osteoclast (bone-resorbing cell) lineages. The activities of these cells are directed by hormones and other molecules that circulate in the blood as well as regulators that are produced locally in the bone. There are a number of bone diseases that are the subject of vigorous research. See also: Blood; Calcium; Connective tissue; Hormone; Protein; Skeletal system

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