The parathyroid glands (the parathyroid glands) ensure and guarantee the production and secretion of the parathyroid or parathyroid hormone . This secretion is internal, that is, endocrine, and parathyroid hormone is a special hormone essential for regulating the metabolism of calcium and phosphorus (but also of other minerals) within the body.
What are parathyroid glands?
The parathyroid glands are glands of moderate size , which reach the size of about 0.5-1 centimeter, and are lined with a fibrous capsule . Inside there are three types of cells : main cells, clear cells and oxyphilic cells . These cells are positioned in a cord, and are respectively small and multifaceted, quite large, or present in the cytoplasm the oxyphiles , or acidophilic granules .
Placed behind the thyroid , they can sometimes present in an intrathyroid position; they are usually four (or two pairs of parathyroid glands), but they can also be five or six. Their nomenclature reflects the close link between the thyroid gland .
In general, two upper and two lower parathyroid glands are distinguished . The upper parathyroid pair is usually located behind the thyroid, while the lower pair is located between the branches of the lower thyroid artery.
What are parathyroid glands for?
The parathyroid glands have the task of producing and secreting the hormone that controls the balance of calcium / phosphates within the body by collaborating in the mechanisms for controlling the presence of calcium in the blood and in maintaining bone health. It is the parathyroid hormone or parathyroid hormone , formed by a chain of 84 amino acids . This hormone stimulates the reabsorption of calcium and the excretion of phosphates in the kidney, and the absorption of calcium in the intestine.
The administration of this hormone produces the passage of calcium from the bones to the blood ; its absence, on the other hand, causes a decrease in the level of calcium in the blood , and the consequent birth of a state of muscular hypertonicity (confirming the very important role that calcium plays in controlling muscle contraction).