Parathyroid gland

A small endocrine gland, usually located behind the thyroid, that secretes parathyroid hormone to regulate calcium and phosphate balance in the blood.

Parathyroid hormone: A peptide hormone that raises blood calcium and influences phosphate balance. It is the gland’s principal secretion and the main signal controlling its effects.
Thyroid gland: An endocrine gland in the neck that produces thyroid hormones and calcitonin. The parathyroid glands usually lie on its posterior surface, though their positions vary.
Primary hyperparathyroidism: A disorder in which one or more parathyroid glands secrete excessive hormone autonomously. It is a common gland-centered cause of elevated blood calcium.
Pharyngeal pouch: An embryonic structure in the developing head and neck that contributes to several organs. Parathyroid glands arise from specific pharyngeal pouches.
Calcium homeostasis: The regulation of calcium concentrations in body fluids and tissues. The gland’s feedback response is a central control mechanism for blood calcium.
Chief cell: The principal parathyroid cell type, responsible for producing and secreting parathyroid hormone. These cells provide the gland’s main endocrine output.
Secondary hyperparathyroidism: Increased parathyroid hormone secretion in response to chronic low calcium or related disturbances. It shows how the glands respond to sustained problems elsewhere, especially kidney disease.
Third pharyngeal pouch: An embryonic pouch that gives rise to the inferior parathyroid glands and thymus. Its descent with the thymus helps explain why inferior glands can lie far from the thyroid.
Kidney: An organ that filters blood, regulates fluid and electrolyte balance, and produces urine. Parathyroid hormone increases renal calcium retention and alters phosphate handling.
Oxyphil cell: A large, mitochondria-rich cell found in parathyroid tissue, with incompletely understood function. It is the other characteristic cell type seen in the gland.

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