This document discusses thyroid disorders and the functions of thyroid hormones. It covers the synthesis of thyroid hormones in the thyroid gland and their binding in the bloodstream. The major actions of thyroid hormones are on metabolism, growth, tissue differentiation, and multiple body systems. Thyroid hormone levels are regulated by the hypothalamic-pituitary-thyroid axis. Common thyroid disorders discussed include hypothyroidism, hyperthyroidism, myxedema, Grave's disease, exophthalmic goiter, and cretinism.

1. THYROID DISORDERS
By
Dr. Ahmed Al-Sayed
M.B.B.Ch, M.Sc, Ph.D (MD)
Lecturer of Medical Physiology
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2. RULESRULES

3. Anatomy
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4. Histology
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5. Case study
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6. ILOs
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7. ILOs
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8. THYROID HORMONE SYNTHESIS
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9. THYROID HORMONE SYNTHESIS
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10. 10

11. THYROID HORMONES
• Occurs in 2 forms
• Free form in plasma
• Bound form
– Bound to:
Albumin
TBG
TBPA
• Fluctuations in
binding
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12. Mechanism of Action
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13. Actions of thyroid Hormones
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Metabolic
Role in Growth & tissue differentiation
Body Systems

14. Actions of thyroid Hormones
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Metabolic
•General metabolism (Calorie genesis):
Increase BMR.
Increase O2 consumption & heat production (thermogenic).
•Carbohydrate metabolism:
Increase glucose uptake by the tissues.
Increase blood glucose level.
Due to:  Glycogenolysis &  Gluconeogenesis.
•Lipid metabolism:
Decrease blood cholesterol and phospholipids.
Due to:  Cholesterol excretion in bile.
•Increase protein synthesis (anabolic):
But, also increase protein breakdown for energy production.
In normal level of thyroid hormones it causes protein synthesis.
 Hormone (as myxedema)   protein anabolism & abnormal proteins.
 Hormones (as thyrotoxicosis)   protein due to  catabolic activity.
•Stimulate conversion of B-Carotenes to vitamin A.

15. Actions of thyroid Hormones
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Systems
Cardiovascular system:
Increase heart rate. Due to:
 O2 consumption in SAN.
 Rhythmicity of SAN.
 Sensitivity of SAN to adrenaline.
( number & affinity of β receptors to catecholamine).
Increase cardiac output. Due to:
Direct action on the heart.
Potentiate the chronotropic & inotropic effects of catecholamine.
( number & affinity of β receptors to catecholamine).
Decrease the peripheral resistance by VD (due to  metabolites).
Increase systolic ABP & decrease diastolic ABP   pulse pressure.
Respiratory system:
Increase pulmonary ventilation.
Muscles:
Essential for normal muscle metabolism & protein synthesis.
Increase or decrease thyroid hormones level cause muscular
weakness (Thyrotoxic myopathy).

16. Actions of thyroid Hormones
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SystemsBlood:
Increase RBCs formation.
Central nervous system:
Thyroxin is essential for normal activity and development of CNS.
Gonads:
Thyroxin is essential for normal activity and development of gonads.
Thyroxin inhibits prolactin hormone.
Mammary gland:
Increase galactopoiesis & maintain milk secretion during lactation.
GIT:
Increase motility & absorption & increase appetite.
Renal:
Cause diuresis & and increase excretion of K+
& Ca++
& phosphate.
•Permissive action: on Catecholamines, Cortisol, GH & Glucagon

17. Actions of thyroid Hormones
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Role in Growth & tissue differentiation
Essential for
Physical , Mental & sexual
Growth & development

18. Regulation of thyroid Hormones
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Hypothalamo-Pituitary –
Thyroid Axis
LATS = TSI =
TSH receptors
stimulators
?

19. Regulation of thyroid Hormones
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20. DISORDERS OF THYROID FUNCTIONS
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Hypothyroidism Hyperthyroidism
Cretinism Myxedema
)thyrotoxicosis)
)Grave’s disease)
)Exophthalmic goiter)

21. Thyrotoxicosis
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23. 23

24. 24

25. 25

26. MYXOEDEMA
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27. 27

28. 28

29. CRETINISM
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30. Cretinism
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32. Case study
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33. ILOs
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34. ILOs
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35. https://www.facebook.com/groups/EnjoyPhysiology

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