Serum calcium and parathyroid function linked to control of respiration.

It is suggested that the plasma concentration of ionized calcium in a complex way is connected to control or respiration in mammals. The level of ionized calcium in plasma is suggested to correlate with the arterial carbon dioxide tension as well as with the arterial oxygen tension. The primary function of the parathyroid glands, which are absent in fish, but develop in land vertebrates, is suggested to be control of plasma calcium and pH in respiratory alkalosis due to hyperventilation.