Microscopic Appearance of the Thyroid Gland Figure 76

Thyroid Hormone Synthesis & Secretion Figure 76 -2; Guyton & Hall Copyright © 2006

Binding of Thyroid Hormones & Precursors to Thyroglobulin during Hormone Synthesis Tyrosine HO H

Actions of Thyroid Hormones Copyright © 2006 by Elsevier, Inc. Figure 76 -5; Guyton

Metabolic Effects of Thyroid Hormones Parameter Basal metabolic rate ↓ T 3, T 4

Hypothalamohypophyseal-Thyroid Axis Hypothalamus TRH + _ Thyrotrope TSH + Thyroid T 3, T 4

Pathophysiology of Thyroid Hormones • Graves’ disease – autoimmune disorder; immune complex mimics TSH

Hypothalamohypophyseal-Thyroid Axis in Graves’ Disease Hypothalamus _ TRH + Thyrotrope TSH + + TSI

Histology of an Islet of Langerhans of the Pancreas Figure 78 -1; Guyton &

Metabolic Effects of Glucagon Glycogen Glucose-P Amino acids Pyruvate Free fatty acids Ketoacids Adipose

Approximate Rates of Insulin & Glucagon Secretion at Different Blood Glucose Levels 100% Glucagon

Anatomy of the Parathyroid Glands & Microscopic Appearance of Chief Cells Figure 79 -9;

PTH Actions • Bone – resorption ( osteoclasts) – osteocytic osteolysis • Kidney –

Plasma Calcium Concentration & PTH Secretion PTH secretion (% maximal rate) 100 50 0

Hypocalcemia Disorder Plasma [PTH] [1, 25 -(OH)2 -D 3] Surgical hypoparathyroidism * Resorption Urine

Primary Hyperparathyroidism Plasma [PTH] Plasma [1, 25 -(OH)2 -D 3] * Bone Resorption Urine

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Binding of Thyroid Hormones & Precursors to Thyroglobulin during Hormone Synthesis Tyrosine HO H H C C H NH 2 COOH 3 -Monoiodotyrosine (MIT) HO H H C C H NH 2 COOH I 3, 5 -Diiodotyrosine (DIT) HO H H C C H NH 2 COOH I I 3, 5, 3’-Triiodothyronine (T 3) HO I O H H C C H NH 2 H H COOH I I 3, 3’, 5’-Triiodothyronine (RT 3) HO I O C C H NH 2 H H C C H NH 2 COOH I I Thyroxine (T 4) HO O I Copyright © 2006 by Elsevier, Inc. I I COOH Thyroglobulin Molecule I

Metabolic Effects of Thyroid Hormones Parameter Basal metabolic rate ↓ T 3, T 4 ↑ T 3, T 4 ↓ ↑ Carbohydrate metabolism ↓ Gluconeogenesis ↓ Glycogenolysis Normal serum [glucose] Protein metabolism ↓ Synthesis ↓ Proteolysis ↑ Synthesis ↑ Proteolysis Muscle wasting Lipid metabolism ↓ Lipogenesis ↓ Lipolysis ↑ Serum [cholesterol] ↑ Lipogenesis ↑ Lipolysis ↓ Serum [cholesterol] Thermogenesis ↓ ↑ Gluconeogenesis ↑ Glycogenolysis Normal serum [glucose] ↑ Table 48 -1, Boron & Boulpaep Copyright © 2006 by Elsevier, Inc.

Pathophysiology of Thyroid Hormones • Graves’ disease – autoimmune disorder; immune complex mimics TSH – stimulates continual production of thyroid hormone – leads to hyperthyroidism and goiter formation. • Cretinism – deficiency of thyroid hormones in childhood – results in severe growth retardation and mental retardation. Copyright © 2006 by Elsevier, Inc.

Metabolic Effects of Glucagon Glycogen Glucose-P Amino acids Pyruvate Free fatty acids Ketoacids Adipose tissue Liver Plasma Stimulate Inhibit Glucose Free fatty acids Ketoacids Amino acids Berne & Levy, Figure 47 -19 Copyright © 2006 by Elsevier, Inc.

Approximate Rates of Insulin & Glucagon Secretion at Different Blood Glucose Levels 100% Glucagon Response ( ) Insulin Response ( ) 100% 50% 0 0 40 Copyright © 2006 by Elsevier, Inc. 80 120 160 200 Plasma glucose (mg/dl) 240

PTH Actions • Bone – resorption ( osteoclasts) – osteocytic osteolysis • Kidney – Ca 2+ reabsorption – phosphate reabsorption – Na+ reabsorption (weak effect) – 1, 25 -(OH)2 -D 3 • Intestine – Ca 2+ absorption – phosphate absorption Copyright © 2006 by Elsevier, Inc.

Hypocalcemia Disorder Plasma [PTH] [1, 25 -(OH)2 -D 3] Surgical hypoparathyroidism * Resorption Urine Phosphate c. AMP Vitamin D deficiency (2°) Chronic renal failure (2°) * Osteomalacia Resorption * Primary events or disturbances Copyright © 2006 by Elsevier, Inc. Bone Plasma [Ca 2+] [Phosphate] * Phosphate c. AMP Osteomalacia Phosphate Resorption ( GFR)* Castanzo, Table 9 -17

Primary Hyperparathyroidism Plasma [PTH] Plasma [1, 25 -(OH)2 -D 3] * Bone Resorption Urine Plasma [Ca 2+] Plasma [Phosphate] Phosphate Ca 2+ c. AMP * Primary disturbance Castanzo, Table 9 -17 Copyright © 2006 by Elsevier, Inc.