The parathyroid hormone or PTH which is released from the parathyroid glands, calcitonin from the thyroid gland and the growth factor interleukin 6 are responsible for the bone resorption. This is a response of the body when there is low calcium in the blood. They stimulate the osteoclast to break down and release the calcium into the blood. In the cellular level, an osteoclast attaches itself to the osteon of the bone then releasing hydrogen ions through carbonic anhydrase which helps dissolution of minerals. It also releases collagenase like Cathepsin K to degrade of type 1 collagen and noncollagenous protein and metalloprotease (MMP) to digest organic compounds. Upon degradation of the bone release calcium and other mineral ions in the blood.
