Anatomy &Functions of thyroid gland & calcitonin

1. Ms.Anu Sebastian: B.Pharm; M.Pharm
Assistant Professor,
Dept. Of Pharmacology
Nirmala College Of Pharmacy
Muvattupuzha,Ernakulam,Ke

2. THYROID GLAND
 It is a butterfly shaped gland,located inferior to larynx &
anterior to trachea.
 The gland is having two lateral lobes(left & right lobes).
 These lobes are located on either sides of trachea.
 These two lobes are connected by a narrow structure called
‘Isthmus’.
 The normal weight of thyroid gland is 30g.
 Normal blood supply- 80 -120 ml/min.

3. Fig: Location of Thyroid gland

4. ANATOMY
 Thyroid gland is made up of microscopic spherical sacs called
thyroid follicles.
 The wall of thyroid follicles are made up of follicular cells
,which produces two hormones thyroxine also called
tetraiodothyronine (T4) & triiodothyronine(T3).
 The follicles are surrounded by basement membrane.
 When the follicular cells are inactive, the shape of cells is
cuboidal to squamous & when the cells are active(by TSH), the
shape is cuboidal to columnar.
 Between the follicles, Parafollicular cells or ‘C’-cells are
present. These cells produce a hormone called calcitonin.

5. FUNCTIONS OF THYROID HORMONES
 Increases basal metabolic rate (BMR), ie the consumption
for ATP production.
 Calorigenic effect : It is the production & utilization of
ATP. As a result of that heat is generated & body
temperature increases,
 Regulate the metabolism of carbohydrate ,proteins
 Increases the use of glucose & fatty acid for ATP
production.

6.  Increases lipolysis & decreases blood cholestrol level.
 Up–regulation of Beta–receptors and enhances the action
of catecholamines.(adrenaline & Nor-adrenaline)
 Along with human growth hormone & insulin thyroid
hormone stimulates the body growth.

7. REGULATION OF HORMONE SYNTHESIS
 The hormone synthesis is regulated by TSH.
 Decrease in the Basal metabolic rate or decrease in the
level of T3 & T4 in blood, will stimulate the TSH release
and increase thyroid hormone synthesis.

8. CALCITONIN
 It is produced by the parafollicular cells of thyroid hormones.
 The main function of calcitonin along with parathormone is
maintanance of blood calcium homeostasis.
 Calcitonin decreses blood calcium level by:
Inhibit the action of osteoclasts.
Accelerates the uptake of calcium & Phosphate ions into bone
matrix.

9. THANK YOU