PARATHYROID GLAND - niu.edu.inniu.edu.in/son/online-classes/parathyroid-Presentation.pdf · PARATHYROID GLAND Human being have four parathyroid glands Situated at back surface of

BY: DR RAJ SHARMA

NOIDA INTERNATIONAL UNIVERSITY

PARATHYROID GLAND

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.