What are the 3 calcium regulating hormones?

Parathyroid hormone:

1. Four parathyroid glands, which are tiny glands in the neck beneath the thyroid gland, store and release parathyroid hormone.
2. Thyroid hormone controls calcium levels in the blood, mostly by raising them when they are too low.
3. It accomplishes this by acting on the kidneys, bones, and gut.
4. PTH's major role is to regulate calcium content in the extracellular fluid, which it achieves via influencing the rate of calcium transport into and out of bone, renal resorption, and GI absorption.
5. The action on the kidneys is the fastest, inducing calcium reabsorption and phosphorus excretion.

Thyrocalcitonin:

1. Thyrocalcitonin, or calcitonin, is a polypeptide hormone generated by the parafollicular or C cells of the thyroid gland.
2. It promotes bone formation by reducing blood calcium and phosphate levels.
3. In birds, fish, and other nonmammalian vertebrates, cells of the glandular ultimobranchial bodies release calcitonin.

Calcitriol:

1. It is derived from Vitamin D and is secreted by the proximal tubular cells in the kidney.
2. Calcitriol, also known as 1,25-dihydroxycholecalciferol, 1alpha,25-dihydroxyvitamin D3, and 1,25-dihydroxyvitamin D3, is an active metabolite of vitamin D having three hydroxyls (OH) groups.