Regulatory Organs
Primarily calcium is regulated by the actions of 1,25-Dihydroxycholecalciferol, parathyroid hormone (PTH) and calcitonin and direct exchange with the bone matrix. Plasma calcium levels are regulated by hormonal and non-hormonal mechanisms. After ingestion of substantial amounts of calcium the short term control that prevents calcium spiking in the serum is absorption by the bone matrix. After about an hour, PTH will be released and not peak for about 8 hours. The PTH is, over time, a very potent regulator of plasma calcium, and controls the conversion of vitamin D into its active form in the kidney. The parathyroid glands are located behind the thyroid, and produce parathyroid hormone in response to low calcium levels.
The parafollicular cells of the thyroid produce calcitonin in response to high calcium levels, but its significance is much smaller than that of PTH.
Read more about this topic: Calcium Metabolism
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