ABSTRACT
This chapter addresses the physiological processes by which the skeletal system contributes to maintenance of extracellular calcium homeostasis through a dual role as both the recipient of calcium ions to maintain skeletal function and the source of calcium ions. These processes can either consolidate or reduce bone mineral status. The chapter will review (1) the mechanisms that control calcium flow into and out of the extracellular fluid; (2) how these systems are regulated to protect the extracellular fluid from excessive changes in calcium concentration; (3) the role of the kidneys in this regulation; (4) how the kidneys can protect from and also cause bone disease and how such outcomes may be managed.
