Parathyroid glands produce parathyroid hormone, which plays a key role in the regulation of calcium levels in the blood. Precise calcium levels are important in the human body, since small changes can cause muscle and nerve problems.
The parathyroid hormone stimulates the following functions:
-Release of calcium by bones into the bloodstream
-Absorption of calcium from food by the intestines
-Conservation of calcium by the kidneys
-Stimulates cells in the kidney to transforms weaker forms of vitamin D into the form that is strongest at absorbing calcium from the intestines