This chapter covers the structure of bone, diseases associated with bones, functions of the bone cells, and hormones responsible for bone development, growth, and maintenance. Bone cells are in constant communication with cells of other systems and also with the extracellular matrix (ECM), which is composed of osteoid, non-mineralized bone tissue and the mineralized bone matrix. One of the bone diseases, osteoporosis is defined as the condition of generalized skeletal fragility in which bone strength is sufficiently weak that fractures occur with minimal trauma, often no more than is applied by routine daily activity. Treatment for osteoporosis includes hormone therapy and the use of bone resorption inhibitors such as the bisphosphonates, and, in addition, stimulators of bone formation such as modified forms of parathyroid hormone (PTH). Another serious genetic bone disease is osteogenesis imperfecta, a heritable disease of bone characterized by recurring bone fractures. It is caused by mutations affecting the structure of the collagen type I molecule, and is the most common single gene defect causing bone disease. One of the bone cells, osteoclast is described histologically as a multinucleated, tartrate-resistant acid phosphatase (TRAP)-positive cell. The sole function of the osteoclast is to resorb bone. Osteoclast precursors are derived from the same stem cell hematopoietic precursors that can become granulocytes and monocytes/macrophages. Cell lines such as RAW 267.4 and MOPC-5 are available that represent osteoclast precursors, as these cells can form TRAP-positive multinucleated cells that resorb bone. Osteocytes are terminally differentiated osteoblasts, making up the majority of all bone cells. During osteocyte ontogeny, the matrix producing osteoblast becomes either a lining cell or a pre-osteocyte embedded in the newly formed osteoid.
|Original language||English (US)|
|Title of host publication||Handbook of Cell Signaling, 2/e|
|Number of pages||16|
|State||Published - Dec 1 2010|
ASJC Scopus subject areas
- Biochemistry, Genetics and Molecular Biology(all)