PARATHYROID GLAND BY: DR RAJ SHARMA NOIDA INTERNATIONAL UNIVERSITY - PowerPoint PPT Presentation

PARATHYROID GLAND BY: DR RAJ SHARMA NOIDA INTERNATIONAL UNIVERSITY

OVERVIEW OF THYROID GLAND Thyroid Essentials:  regulates your metabolism  Butterfly-shaped gland wrapped around trachea  The two main thyroid hormones are T3 and T4.  Appear on front of the neck

 Thyroid disorders are common, and they include goiters, hyperthyroidism, and hypothyroidism.

PARATHYROID GLAND  Human being have four parathyroid glands  Situated at back surface of the thyroid gland  Located in neck  Very small in size  Measures- •6mm long •3mm wide & •2mm thick  Dark brown in colour

DIAGRAMATIC VIEW :

FUNCTIONS OF PARATHYROID GLAND  main function : produce and secrete a hormone called PTH (parathyroid hormone)  raises blood calcium level

HISTOLOGY (microscopic study)  made up of chief cells and oxyphil cells 1.CHIEF CELLS: secretes PTH (parathyroid hormone) 2.OXYPHIL CELLS: •degenerates chief cells • may secrete PTH during pathological condition called parathyroid adonema (a small tumour of PT gland)  gland inc. In size due to production of PTH in excess.

SOURCE OF SECRETION  secreted by the chief cells of the parathyroid gland

PARATHYROID HORMONE  regulates calcium, magnesium, phosphorus levels in blood.  Main function is to increase Calcium levels when they are low

ROLE OF ‘Ca’ IN OUR BODY  Bone&teeeth formation  Neuronal activity  Skeletal muscle activity  Cardiac activity  Smooth muscle activity  Secretory activity  Cell division & growth  Coagulation of blood

CHEMISTRY  Parathyroid hormone is protein in nature  Having 84amino acids  Having molecular weight :- 9,500 Da

SYNTHESIS  Synthesised from precursor called pre-pro-PTH containing 115 amino acids. PRE-PARATHYROID HORMONE ⬇ PRO-PARATHYROID HORMONE ⬇ PARATHYROID HORMONE

PROCESS OF SYNTHESIS OF PTH 1. pre-PTH hormone (115 amino acids) enters the endoplasmic reticulum of the chief cells of PT gland. 2. Then there,it is converted into a Pro- hormone called pro-PT hormone . 3. Lastly, pro-PTH enters the golgi apparatus,and converted into PARATHYROID HORMONE.

ACTIONS OF PTH ON BLOOD ‘CA’ LEVEL  Primary action of parathyroid hormone is to maintain the blood calcium level.  PTH maintains blood CA level by :-  Resorption of Ca from bones  Reabsorption of Ca from the renal tubules (kidney)  Absorption of Ca from intestine

ROLE OF PTH IN THE ACTIVATION OF VITAMIN D  Vitamin D is very essential for calcium absorption from the intestine.  But vitamin D itself is not an active substance.  So, PTH is the one who is enabling the kidney to produce Vitamin D which inturn goes to intestine and stimulates more absorption of Calcium.

BLOOD LEVEL OF CALCIUM  PTH secretion is inversely proportional to blood calcium level.  ⬆ in blood calcium level ⬇ PTH secretion.  CONDITIONS WHEN PTH SECRETION DECREASES:- ⭐ excess quantities of calcium in diet. ⭐ increase vitamin D in diet. ⭐ increased releasing of calcium from the bones, caused by factor such as bone diseases.

PARATHYROID DISORDERS  HYPERPARATHYROIDISM : increased PTH levels in blood 🔺 results to :- HYPERCALCEMIA i.e too much calcium in the blood.

 HYPOPARATHYROIDISM : decreased secretion of PARATHYROID HORMONE. : results to HYPOCALCEMIA i.e too little calcium in the blood.