Thyroid gland

anatomy physiology of thyroid gland..basic information for beginners.

1. THYROID GLAND

2. CONTENT TO BE COVERED Anatomy and Physiology of thyroid gland Microscopic structure of thyroid gland Thyroid hormone synthesis, secretion and storage Pathological role of thyroid hormone Thyroid hormone and their disorders

3. Anatomy and Physiology of thyroid gland A butterfly-shaped organ the   thyroid gland  is located anterior to the trachea, just inferior to the larynx The medial region, called the isthmus, is flanked by wing-shaped left and right lobes. Each of the thyroid lobes are embedded with parathyroid glands, primarily on their posterior surfaces.

4. Lobe size 5 cm long and 3cm width; cone shaped lope Organ weight is 25 g This organ developed 3 months of age Location 5,6,7 th cervical and 1 st thoracic vertebrae Blood supply: Arterial blood supply to the gland through the superior and inferior thyroid gland

5. The tissue of the thyroid gland is composed mostly of thyroid follicles. The follicles are made up of a central cavity filled with a sticky fluid called  colloid . Surrounded by a wall of epithelial follicle cells, the colloid is the center of thyroid hormone production, and that production is dependent on the hormones’ essential and unique component: iodine. Between the follicles single or small groups cells; parafollicular cells, also called as c-cells which secrete the calcitonin hormone

6. Microscopic structure of thyroid gland

7. Thyroid hormone Hormone : A hormone is any member of a class of signalling molecules , produced by glands in multicellulae organisms, that are transported by the circulatory system to target the distant organs and regulate physiology and behavior. Thyroid hormones: T3(tri iodothyronine ) T4 ( thyroxine ) Calcitonin

8. Synthesis Storage and Release Four M ain S teps Uptake of iodide Incorporation : iodide into iodine Coupling of iodine to form thyroid hormone Diffusion of thyroid hormone

9. Physiological Function of T3 and T4 Improve the mental strength Enhances the effect of other hormones like adrenaline and nor adrenaline Increasing the basal metabolic rate and heat production Regulating the metabolism of carbhohydrates , proteins and fats

10. Calcitonin This hormone secreted by the parafollicular or C-cells in thyroid gland It acts on bone cells and the kidneys to reduces the blood calcium levels when they are raised . It promotes storage of calcium in bones and inhibits the reabsorbtion of calcium by the renal tubules

11. Thyroid gland disorders Two main categories Abnormal secretion of thyroid hormones -Hyperthyroidism -Hypothyroidism Goitre

12. Hyper thyroidism Also known as thyrotoxicosis Body tissues are exposed to excessive T3 and T4 It increases the basal metabolic rate. Hypothyroidism Insufficient T3 and T4 secretion It causes the congenital hypothyroidism in childrens Myxoedema in adults.

13. HYPERTHYROIDISM

14. Goitre Enlargement of the thyroid gland without signs of hyperthyroidism Relative lack of T3 and T4, low level stimulation of TSH resulting in hyperplasia of the thyroid gland. Reasons: Persistent iodine deficiency Genetic abnormality affecting the T3 and T4

15. THANK YOU