Chemistry. Chemical element with the symbol Ca. It is a member of the alkaline earth family of metals. Calcium is the most abundant mineral in the body. More than 99 % of calcium is bound as calcium hydroxyapatite extracellular in the bones and teeth. It is essential for the function of nerves, muscle contraction, blood coagulation and heart function. Calcium is higher concentrated in the extracellular fluid than intracellular and flows after depolarization of the cell membrane through ion channels into the cell.