The endocrine glands and hormones that are responsible for maintaining calcium homeostasis, are thyroid and parathyroid glands and their associated hormones are caicitonin and Parathyroid Hormone (PTH).
(i) Parathyroid glands are the glands developed from the endoderm of the embryo. The cells of parathyroid glands are of two types, i.e., chief cells and oxyphii cells. The chief cells of the parathyroid glands secrete parathyroid hormone (PTH).
This hormone (PTH) is involved in regulating calcium and phosphate balance between the blood and other tissue. It mobilises the release of calcium into the blood from bones. PTH increases calcium reabsorption by the body organs iike intestine and kidneys.
(ii) Thyroid gland is the largest endocrine gland located anterior to the thyroid cartilage 0f the larynx in the neck. This gland plays a vital role in maintaining calcium homeostasis. it releases thyrocaicitonin hormone produced by the parafoilicuiar cells, also called ‘0’ cells.
This hormone is secreted when the calcium level in blood gets high. it is a 32 amino acid peptide hormone that lowers the calcium level by suppressing release of calcium ions from the bones. Thus, caicitonin has an action opposite to that of the parathyrond hormone on calcium homeostasis.
