Bone metabolism

It is a common misconception that bones are static in nature and hardly change once an individual becomes an adult. On the contrary, bones are continuously undergoing a dynamic process of resorption and deposition known as bone metabolism.

The cells responsible for bone metabolism are known as osteoblasts, which secrete new bone, and osteoclasts which break bone down. The structure of bones as well as adequate supply of calcium requires close cooperation between these two types of cells. It relies on complex signaling pathways to achieve proper rates of growth and differentiation. These signaling pathways include the action of several hormones, including parathyroid hormone (PTH), vitamin D, growth hormone, steroids, and calcitonin, as well as several cytokines. It is in this way that the body is able to maintain proper levels of calcium required for physiological processes.