Searchable abstracts of presentations at key conferences on calcified tissues
Bone Abstracts (2016) 5 AHP1.1 | DOI: 10.1530/boneabs.5.AHP1.1

ECTS2016 Allied Health Professionals Session Speakers (4 abstracts)

Bone Structure and Function: Organization & composition of bone, bone modelling and remodelling, bone cells

Tim Arnett


Department of Cell & Developmental Biology, University College London, London, UK.


It is not hard to gain a working understanding of the composition and function of bone that can offer useful insights into the causes of common bone disorders such as osteoporosis. Osteoblasts are the bone forming cells. They work in teams to lay down type 1 collagen fibres (similar to the collagen in skin and internal organs). The newly formed collagen in bone is initially soft and flexible. Osteoblasts possess the special ability to mineralise this collagen with a form of calcium phosphate (hydroxyapatite) in order to form bone, which is thus a composite material. The hydroxyapatite makes the bone hard and resistant to compression or bending, and the collagen holds it together and prevents brittleness. Osteocytes are osteoblasts that have become trapped in the bone matrix they are forming. Osteocytes are connected to each other (and to osteoblasts) by innumerable fine processes, forming a living network that comprises >90% of all the cells in bone. Osteocytes are thought to have a major function in detecting and co-ordinating the responses of bone to the slight deformation it experiences when subjected to shocks or loads. They may also play a key role in preventing bone from becoming too highly mineralised (and thus brittle). Osteoclasts are large cells that are responsible for the destruction of bone. They are formed from the fusion of immature white blood (or marrow) cells. Osteoclasts attach tightly to the surface of bone matrix and excavate characteristic, sharply-defined pits. This dramatic process, called bone resorption, involves dissolving away the calcium phosphate mineral and fragmenting the tough collagen fibres. Osteoblasts, osteoclasts and osteocytes work together throughout life to create, remodel and repair bone. In early life bone forms rapidly but is of relatively low quality and serves only a temporary role. Juvenile bone is eventually removed by osteoclasts and slowly replaced by high quality adult bone that is laid down in regular layers, rather like plywood. In adult humans, bone remodelling is highly responsive to alteration of mechanical loading but normally remains in overall balance. With advancing age, and in many disease settings, the destructive activity of osteoclasts can begin to outstrip bone formation by osteoblasts, leading to net bone loss. This process can be rapid in the “honeycomb” (trabecular) bone that is present inside the vertebrae and at the ends of the long bones. Bone resorption by osteoclasts is swift compared with the rate of bone formation by osteoblasts, and drugs that target osteoclasts have proven to be particularly useful for treating bone loss disorders.

Volume 5

43rd Annual European Calcified Tissue Society Congress

Rome, Italy
14 May 2016 - 17 May 2016

European Calcified Tissue Society 

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