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8-Jul-16Thyroid Hormones1 Normal Functions HyperthyroidismHypothyroidism
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8-Jul-16Thyroid Hormones2 Two principal hormones Thyroxin (T 4 ) Thyroxin (T 4 ) Triiodothyronin (T 3 ) Triiodothyronin (T 3 ) Others Calcitonin Calcitonin Parathyroid hormones Parathyroid hormones
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8-Jul-16Thyroid Hormones3 Thyroid Hormones Effects Cellular metabolic activity Thyroid hormone Metabolic activity of almost all tissues Metabolic activity of almost all tissues BMR can to 60 – 100% above normal BMR can to 60 – 100% above normal Rate for utilization of food for energy is increased Rate for utilization of food for energy is increased Rate of protein synthesis but also the rate of prot catabolism Rate of protein synthesis but also the rate of prot catabolism
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8-Jul-16Thyroid Hormones4 Thyroid Hormones Effects Growth rate of young people accelerated Mental processes excited Activity of most other endocrine glands are increased Increase in mitochondria Increase membrane active transport mechanism
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8-Jul-16Thyroid Hormones5 Effect on Growth In children Hypothyroid causes Hypothyroid causes Retarded growth In those who are hyperthyroid In those who are hyperthyroid Excessive skeletal growth Giant Thyroid hormone promote growth and development of brain During fetal life During fetal life
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8-Jul-16Thyroid Hormones6 Effect on Carbohydrate Stimulate all aspect of carbohydrate metabolism Uptake of glucose by cells Uptake of glucose by cells Enhanced glycolysis Enhanced glycolysis Enhanced gluconeogenesis Enhanced gluconeogenesis Absorption by GIT Absorption by GIT insulin secretion insulin secretion
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8-Jul-16Thyroid Hormones7 Effect on Fat Thyroid hormones Enhance all aspects of fat metabolism Rapid mobilization of lipids from adipose tissues Rapid mobilization of lipids from adipose tissues In fat stores in FFA conc in plasma in FFA conc in plasma Increased FA oxidation by cells Increased FA oxidation by cells
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8-Jul-16Thyroid Hormones8 Effect on Fat Effect on plasma & liver fat Thyroid hormones conc of cholesterol, phospholipids, TG in plasma conc of cholesterol, phospholipids, TG in plasma But increase FFA But increase FFA Thyroid hormones Increase conc of cholesterol, phospholipids, TG Increase conc of cholesterol, phospholipids, TG Cause excessive deposition of fat in liver Cause excessive deposition of fat in liver
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8-Jul-16Thyroid Hormones9 Effect on Fat Cholesterol can lead to artherosclerosis Thyroid hormone Increase cholesterol secretion in bile Increase cholesterol secretion in bile
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8-Jul-16Thyroid Hormones10 Specific effects On CVS Decrease TPR Decrease TPR Heat & waste products Increase 2:3 DPG Increase 2:3 DPG Relative tissue hypoxia Increase sensitivity and number Increase sensitivity and number Β-adrenergic receptors ↑ CO Increase blood flow to all tissues except brain Increase blood flow to all tissues except brain
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8-Jul-16Thyroid Hormones11 Specific Effects Increase O 2 consumption in most tissue except Testes, brain, erythrocytes, spleen Testes, brain, erythrocytes, spleen GIT Increase absorption of Increase absorption of Vitamins A, B 12, Iron CNS Promote normal Brain development Brain development Myelination Myelination Excitability of tissues & reflexes Excitability of tissues & reflexes Potentiation of catecholamines
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8-Jul-16Thyroid Hormones12 Abnormal Thyroid Functions HyperthyroidismHypothyroidism
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8-Jul-16Thyroid Hormones13 Hyperthyroidism Primary Secondary
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8-Jul-16Thyroid Hormones14 Primary Hyperthyroidism Associated with Associated with Low TSH Hyperplasia of the gland An auto immune response An auto immune response More than 50% of patients More than 50% of patients Show eye signs Grave’s disease
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8-Jul-16Thyroid Hormones15 Primary Hyperthyroidism Grave’s diseases Exophthalmic goiter Exophthalmic goiter Thyroid gland becomes Thyroid gland becomes Enlarged Hyperplastic Long acting thyroid stimulator (LATS) Long acting thyroid stimulator protector (LATS-protector) TSH levels normal TSH levels normal
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8-Jul-16Thyroid Hormones16 Secondary Hyperthyroidism Hypothalamic or pituitary in origin Associated with high plasma THRH Plasma TSH levels are raised
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8-Jul-16Thyroid Hormones17 Clinical Manifestation These are exaggerated effects of Normal thyroid functions on Normal thyroid functions on CVS, GIT, CNS Metabolism These include Heat intolerance Heat intolerance Raised CO Raised CO HR HR Emotional irritability Emotional irritability Fine tremors Fine tremors
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8-Jul-16Thyroid Hormones18 Complications of Hyperthyroidism Exopthalmos High output cardiac failure Inadequate tissue perfusion Despite the compensatory Co Despite the compensatory Co Liver failure demand energy, vitamins demand energy, vitamins Depletion of vit A, B 12 Anaemia Depletion of glycogen Depletion of glycogen Liver becomes more susceptible to injury & failure
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8-Jul-16Thyroid Hormones19 Hypothyroidism Decreased or suppressed TH activity Could Primary hypothyroidism Primary hypothyroidism Secondary hypothyroidism Secondary hypothyroidism
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8-Jul-16Thyroid Hormones20 Primary hypothyroidism Decreased or suppressed activity of TH Due to diseases of the thyroid gland Due to diseases of the thyroid gland Associated with autoimmune response Hashimoto’s disease Hashimoto’s disease Some are due to idiopathic non-toxic goiter
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8-Jul-16Thyroid Hormones21 Secondary Hypothyroidism May be due to Failure of pituitary or hypothalamus Failure of pituitary or hypothalamus Iodine deficiency Iodine deficiency Presence of goitrogenic substances Presence of goitrogenic substances Carbamazole Cabbages
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8-Jul-16Thyroid Hormones22 Secondary Hypothyroidism Thyroid gland respond to a dose of TSH To differentiate hypothyroidism Secondary for Pituitary or hypothalamic failure Secondary for Pituitary or hypothalamic failure Exogenous TRH administration in plasma TSH if the problem is due to hypothalamic failure in plasma TSH if the problem is due to hypothalamic failure There is no in plasma TSH if the failure is of pituitary gland There is no in plasma TSH if the failure is of pituitary gland
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8-Jul-16Thyroid Hormones23 Manifestations of Hypothyroidism In adults Called myxodema Called myxodema Characteristic skin changes Characteristic skin changes Skin dry, yellowish (carotenemia) Carotene retention in the skin BMR falls to about 40% of normal BMR falls to about 40% of normal Poor tolerance to cold Poor tolerance to cold Voice husky and slow Voice husky and slow Mental activity Mental activity Slow, poor memory Severe mental illness (myxodema madness)
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8-Jul-16Thyroid Hormones24 Manifestations of Hypothyroidism In children and young Cretinism Cretinism Dwarfed, retarded growth Mentally retarded dwarfs Mentally retarded dwarfs Reduced nerve cells and axons in CNS Reduction in myelination Enlarged protruded tongue Enlarged protruded tongue Speech problems Pot bellied due to Pot bellied due to Accumulation of fluids in abdominal cavity
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