what is Parathyroid gland?




Parathyroid gland: structure, location and Hormones

Structural anatomy of Parathyroid gland

  • Parathyroid glands are tiny, lentil sized gland embeded in posterior of thyroid gland.
  • two pairs of parathyroid glands are found.
  • each thyroid lobe contains two parathyroid gland.
  • The gland is composed of principal cells (secrete parathormone) and Oxyphilic cells (store parathormone)

Location: embedded on posterior of thyroid gland

Size: small lentil sized, 4 in number

Hormones of Parathyroid gland

  1. Parathormone

  • Regulate the concentration of calcium and phosphate level in blood
  • Increase level of Ca++ in blood by reabsorption from intestine and kidney, Osteolysis
  • Low Ca++ concentration in blood stimulate parathormone synthesis.
  • Promote decalcification and demineralization of bone.
  • stimulates Osteoclast to break (Osteolysis) to release Calcium from bone to blood.

* Improper balance of calcium and phosphate in blood causes faulty nerve impulse transmission, destruction of bone tissue, hamper bone growth and muscle tetany.

** when calcium level increases in blood, parathormone stimulates inhibition of reabasorption of calcium in kidney and inhibit osteolysis of bone.

 Disorder of Parathyroid gland:

1. Parathyroid tetany:

  • deficiency of parathormone
  • muscle spasms, sustained contractions of muscles
  • may leads to death

2. Osteoporosis:

  • over secretion of parathormone
  • decalcification of bones
  • bone becomes soft and porous

Parathyroid gland: structure, location and Hormones