Describe The Parathyroid Gland

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Parathyroid gland:-

There are four parathyroid gland at the four corners on the posterior surface (dorsal side) of the thyroid gland embedded in its tissue. They are reddish or yellowish-Brown, Slightly flattened oval bodies 6 or 7 mm long , 3 or 4 mm wide and 1 or 2 mm thick. All four parathyroid glands weight approximately 0.05-0.3 gm. Parathyroid gland originates from the rudiments of third and fourth branchial pouches of the embryo. It means that they are endosermal in origin.

Functions of parathyroid hormone:-

Parathyroid hormone (Parathromone, PTH)Plays an important role in maintenance of the internal hormeostasis of the body by regulating the concentrations of calcium and phosphate ions in the blood. The main sites of actions of this hormone are bones and kidneys. It releases calcium and phosphorus into blood by stimulating decomposition of bones through bone degenerating cells osteoclaste.

Parathormone and vitamin ‘D3 act synergistically. When the amount of calcium increase in the blood under the influence of parathormone then ostecblast are stimulated to form new bone tissues due to the presence of 1,∝ 25 dihydroxy cholecalciferol in the form of vitamin D3.

The amount of calcium in our body is highest among all mineral elements. Body of an adult human being contain about 1 kg of calcium out of which about 99 % calcium is found in the bones and remaining 1% in blood plasma. Calcium ions play important role in heart beat muscle contraction conduction of nerve impulse blood clotting and bone and teeth formation.

Hormonal imbalance and disease s caused by it :-

Hypoparathyroidism:-

Hpoparathyoidism may be congenital or acquired. Lack of parathormone in childhood result into stunting of growth, Defective tooth development and mental retardation.

Hyperparathyroidism:-

Hyperparathyroidism aries rarely. Production of parathormone increases due to the formation of malignant tumour called parathyroid adenoma in the gland which result into increase in the calcium and decrease in the phosphate level of blood.