[Regulation mechanisms of bone metabolism]

The bone is continuously in a remodelling process. Bone mass is maintained in a continuous balance between its destruction and formation. Bone remodelling proceeds in a highly regulated cycle in which osteoclasts adhere to bone and subsequently remove it by acidification and proteolytic digestion and the osteoblasts secrete a organic matrix which is calcified into new bone. Bone remodelling is the cellular basis of bone metabolism. Pathological changes in many metabolic bone diseases can be explained by abnormalities at some point of the remodelling cycle. The mechanisms of regulatory bone metabolism involve the availability of a number of minerals and ionic homeostasis, systemic hormones and numerous local factors. In this work the general pattern of bone remodelling and the cellular mechanisms of bone resorption and formation are briefly described. The role of systemic and local factors in the regulation and coupling of these two processes is also reported.