Roles of Electrolytes: Calcium and Phosphate

Calcium, the most abundant mineral in the body, is mainly stored in the skeleton and teeth, combining with phosphate to form mineral salts.

Similarly, most of the phosphate in the body is present as calcium phosphate in the bones and teeth.

In body fluids, calcium exists as an extracellular cation, playing vital roles in blood clotting, neurotransmitter release, muscle tone maintenance, and nervous and muscle tissue excitability.

On the other hand, phosphate ions are important intracellular anions and buffers. They are mostly bound to organic molecules like lipids, carbohydrates, nucleic acids, and ATP.

The parathyroid hormone, or PTH, is the primary regulator of plasma calcium and phosphate concentration.

PTH activates osteoclasts that break down the bone matrix, releasing calcium and phosphate ions into the blood.

In the kidneys, PTH enhances calcium reabsorption and decreases phosphate ion reabsorption, ensuring calcium conservation and phosphate excretion.

PTH also stimulates calcitriol release, which increases calcium and phosphate absorption in the small intestine.