Calcitonin
Calcitonin opposes the action of parathyroid hormone.
increases Ca++ (but not phosphate) reabsorption from the glomerular filtrate of kidney nephrons
PTH is made up of principal cells that secrete PTH and and oxophils (esosinophilic). PTH is secreted when levels of Ca2+ in the blood is low.
HIThe calcium levels in the blood usually contribute and control to the secretion of the parathyroid hormones.