Calcium phosphide Calcium phosphide Calcium phosphide (CP) is the inorganic compound with the formula CaP. It is one of several phosphides of calcium, being described as the salt-like material composed of Ca and P. Other, more exotic calcium phosphides have the formula CaP, CaP, CaP, and CaP. CaP has the appearance of red-brown crystalline powder or grey lumps. Its trade name is Photophor for the incendiary use or Polytanol for the use as rodenticide. It may be formed by reaction of the elements, but it is more commonly prepared by carbothermal reduction of calcium phosphate: The structure of the room temperature form
Calcium metabolism excretion of calcium is relatively modest (about 5 mmol/day) in comparison to what can be excreted via the feces (15 mmol/day). The plasma ionized calcium concentration is regulated within narrow limits (1.3–1.5 mmol/L). This is achieved by both the parafollicular cells of the thyroid gland, and the parathyroid glands constantly sensing (i.e. measuring) the concentration of calcium ions in the blood flowing through them. When the concentration rises the parafollicular cells of the thyroid gland increase their secretion of calcitonin (a proteinaceous hormone) into the blood. At the same time the parathyroid glands reduce their rate of parathyroid hormone (or