Other Definitions
parathyroid gland (dict)
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Parathyroid GlandThe parathyroid glands are endocrine glands in the neck, usually located within the thyroid gland, which produce parathyroid hormone. Most often there are four parathyroid glands but have been known to number six or eight. Anatomy There are two types of cells in the parathyroid glands parathyroid chief cells and oxyphil cells. Physiology Parathyroid hormone is a small protein that takes part in the control of calcium and phosphorus homeostasis, as well as bone physiology. When blood calcium levels drop below a certain point, calcium-sensing receptors in the parathyroid gland are activated to release hormone into the blood. It then stimulates osteoclasts to break down bone and release calcium into the blood. The sole purpose of the parathyroid glands are to regulate the calcium level in our bodies within a very narrow range so that the nervous and muscular systems can function properly. Role in disease Disorders of the parathyroid hormone receptor have been associated with Jansen's metaphyseal chondroplasia and Blomstrand's chondroplasia. The single major disease of parathyroid glands is overactivity of one or more of the parathyroid lobes which make too much parathyroid hormone causing a potentially serious calcium imbalance. This is called hyperparathyroidism; it leads to hypercalcemia and osteitis fibrosa cystica. Since hyperparathyroidism was first described in 1925, the symptoms have become known as "moans, groans, stones, and bones." The primary treatment for this disease is the surgical removal of the faulty lobe. External links
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