Physiology of Thyroid gland 9-10-2010

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dear Dr. Kannan, Can you please allow me to download your presentation for educational purpose. Thank you Gregory Viste

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Physiology of Thyroid gland : 

Moderator – Prof. Dr. G. Mohan M.S Presented by Dr. S. Vijay Kannan MS (Gen) PG Physiology of Thyroid gland

The Thyroid : 

Uniqueness: Only tissue that can both concentrate and organify ingested iodide. Large store of hormone in extracellular depot contained within the follicles of the gland The Thyroid

Histology : 

Histology Functional unit of thyroid gland – Acinus or thyroid follicle.

Thyroid Hormones : 

Thyroid Hormones

Hormones in circulation : 

Strongly bound to serum proteins Bound to ( in decreasing order of affinity) Thyroxine Binding Globulin Thyroxine Binding Pre Albumin Serum albumin Drugs competing with binding: Salicylates Hydantoins Diclofenac Hormones in circulation

Free thyroid hormones : 

Majority of cells cannot take up in bound form. Normal individuals – Total thyroid hormones mirror the Free hormones In Altered binding protein concentration,  Binding Proteins  Bound T3 and T4  Binding Proteins  Bound T3 and T4 Free thyroid hormones

Slide 7: 

States of elevated Thyroxine Binding Globulins Pregnancy Estrogen therapy and oral contraceptives Hypothyroidism States of decreased Thyroxine Binding Globulins Protein malnutrition Cirrhosis Androgens Acute and chronic illnesses Hyperthyroidism

Thyroid Hormones… : 

Thyroid Hormones…

Synthesis of Thyroid Hormones : 

Synthesis of Thyroid Hormones

Iodine Trapping : 

I- I- COLLOID BLOOD Iodine Trapping

Factors affecting iodide [I-] uptake : 

Factors affecting iodide [I-] uptake Enhancers: TSH Iodine deficiency TSH receptor antibodies Autoregulation Inhibitors: I- excess Cardiac glycosides( Digoxin, Ouabain) Perchlorate Bromides & Nitrates

Slide 12: 

Formation & Secretion of TG Oxidation of iodide ions & Iodination of TG

Coupling : 

Coupling

Storage & Release : 

Storage & Release TSH

Peripheral conversion & Catabolism of T4 : 

Peripheral conversion & Catabolism of T4 PropylThiouracil

Stimulators of T4 and T3 release : 

TSH VIP (vasoactive intestinal peptide) β-adrenergic agonists Long-Acting Thyroid Stimulators (LATS) / Thyroid Stimulating Immunoglobulins (TSI) Low temperature Stimulators of T4 and T3 release

Regulation of Thyroid Hormones : 

Regulation of Thyroid Hormones

Effect of TSH on Thyroid Gland : 

Effect of TSH on Thyroid Gland

Physiological effects of thyroid hormones : 

Physiological effects of thyroid hormones

Effect of Thyroid Hormones : 

Effect of Thyroid Hormones

Slide 21: 

Metabolic Actions

Slide 22: 

Metabolic Actions

Action on specific organ Systems : 

Action on specific organ Systems

Action on specific organ Systems : 

Action on specific organ Systems

Pathophysiology : 

Pathophysiology

Hypothyroidism : 

Hypothyroidism

Hyperthyroidism : 

Hyperthyroidism

Summary : 

Summary Regulated by the hypothalamic-pituitary-thyroid axis. Dietary iodine is required for thyroid hormone synthesis. Thyroid hormones undergo metabolism in peripheral tissues, leading to the production of the more active T3. Hormone receptors are located intracellularly, bound to DNA, and alter gene transcription upon binding by thyroid hormone. Hormone actions are systemic and vital for growth, development and metabolism.

References : 

Essential Endocrinology (4th ed) Harrisons Endocrinology (16th ed) Medical Physiology by Kibble & Halsey Endocrine Physiology, 2nd Edition by Patricia E. Molina Medical physiology by Ganong References

Thank you : 

Thank you