What are storage sites for calcium?

Calcium is primarily stored in the bones and teeth, where it is a key component of hydroxyapatite, providing structural support and strength. Additionally, small amounts of calcium are found in the bloodstream, where it plays critical roles in muscle contraction, nerve transmission, and blood clotting. Intracellularly, calcium is stored in the endoplasmic reticulum and mitochondria, which regulate its release for cellular signaling processes.