hormone

1. INTRODUCTION
TO THYROID HORMONE
FARRA NAJWA BINTI ABDUL AZIM
082015100035

2. LEARNING OBJECTIVES
AT THE END OF THE SEMINAR, STUDENTS SHOULD BE ABLE TO :
• DESCRIBE THE MORPHOLOGY OF THYROID GLAND
• DESCRIBE THE HIGHER LEVEL OF CONTROL
• LIST THE HORMONES PRODUCED BY THE THYROID GLAND
• UNDERSTAND THE FUNCTION OF THYROID HORMONES

3. MORPHOLOGY OF THYROID GLAND
• Largest gland (15 – 25 gm)
• Located at in inferior of thyroid cartilage
• Butterfly in shape
• Two lobes ; left and right ; isthmus
• Microscopic of thyroid follicles and C cells
• T4 and T3 present in colloid bound to large
protein -> thyroglobulin

4. HIGHER LEVEL OF CONTROL
Hypothalamus
Releasing & Inhibiting Hormones
Blood Vessels (Median Eminence)
Hypothalamo-hypophyseal Portal
Vessels
Anterior Pituitary

5. HIGHER LEVEL OF CONTROL
Releasing hormones:
1. Thyrotropin-releasing hormone (TRH)
2. Corticotropin-releasing hormone (CRH)
3. Growth hormone-releasing hormone (GHRH)
4. Gonadotropin-releasing hormone (GnRH)
5. Prolactin-releasing hormone (TRH)

6. HYPOTHALAMIC – PITUITARY AXIS

7. HORMONES
• Thyroid hormones are essential for normal growth of tissue and also
stimulates basal metabolic rate.
• Consists of :
• Thyroxine (T4)
• 2 tyrosines + 4 bound iodine atoms
• Triiodothyronine (T3)
• Main hormone secreted
• By follicular cells
• Amino acid derivaties ( tyrosine )
• 2 tyrosines + 3 bound iodine atoms
• Thyrocalcitonin
• By parafollicular cells – C cells

8. HORMONES
• Synthesis of T4 and T3 are stimulated by :
• Increase of thyroid stimulating hormone (TSH)
• Synthesis of T4 and T3 are reduced by:
• Decrease in thyroid stimulating hormone (TSH)
• Glucocorticoid, dopamine and somatostatin
• Normal TSH level is 0.5-5 microunits per ml.
• Low TSH level leads to hypothyroidism
• High TSH level leads to hyperthyroidism

9. FUNCTIONS

10. FUNCTIONS
• BRAIN – Development of nervous system
• BONE & TISSUE – Linear growth, maturation of bones
• CVS – Increases contractility, heart rate, cardiac output
• GUT – Increase absorption of nutrients, motility
• LIVER – increase glucogenesis & glycogenolysis
• ADIPOSE TISSUE – Increased lipolysis
• MUSCLE – Increase protein catabolism
• KIDNEY – Increase erythropoietin
• RESPIRATION – Increase central stimulation
• ENERGY METABOLISM – Increase BMR, oxygen consumption, heat
production stimulation of Na-K-ATPase

11. SUMMARY
• SHAPE, SIZE
• LOCATION
• MICROSCOPIC
• LOBES
MORPHOLOGY
• HYPOTHALAMUS
• PITUITARY GLAND
• HYPOTHALAMO – PITUITARY AXIS
HIGHER LEVEL OF
CONTROL
• THYROXINE (T4)
• TRIIODOTHYROXINE (T3)
• THYROCALCITONIN
HORMONES
• METABOLIC FUNCTION
• GROWTH
• BUILDING OF BONE
• USE OF GLUCOSE FOR ATP PRODUCTION
FUNCTIONS

12. REFERENCE
• TEXTBOOK OF BIOCHEMISTRY FOR MEDICAL STUDENTS, DM
VASUDEVAN, 6TH EDITION