Write short notes on the functions of parathyroid hormone (PTH).

Hint: Parathyroid hormone peptide hormone which is composed of amino acids linked through peptide bonds and are responsible to maintain Homeostasis in the human body by acting as a signaling molecule. This hormone is secreted in parathyroid glands and is also known as parathormone and parathyroid.

Complete Answer:
- Parathormone or parathyroid hormone (PTH) function is to regulate the serum calcium level as their effect on calcium related or dependent organs such as bone, kidney, and intestine.
- Parathormone is produced by certain specialised cells called chief cells which are found in parathyroid glands which are found in the posterior surface of thyroid glands and are of pea size.
- Parathyroid hormone is produced in its precursor form which is inactive known as prohormone. This prohormone becomes activated as they get split into 84 amino acids containing peptide molecules.
- PTH is required for serum calcium concentration maintenance, this can be monitored by a calcium sensing receptor found on the surface of cells of parathyroid glands.
- If there is an increase in ionic calcium concentration there is increased attachment of calcium to respective receptors, this causes decreases in the secretion of parathyroid hormone.
- Conversely the reverse is seen in case of decreased concentration of calcium. Therefore, secretion of parathyroid hormone is internally proportional to the concentration of calcium and its receptor binding complex.

Note: Parathyroid hormone (PTH) is very much essential to maintain bodily homeostasis, alteration in the concentration of secretion of parathyroid hormone can cause diseases called as hyperparathyroidism where there is increased secretion of parathyroid hormone and hypoparathyroidism where There is decreased concentration of parathyroid hormone.