Copyright © 2006 by Elsevier, Inc. Microscopic Appearance of the Thyroid Gland Figure 76-1; Guyton & Hall
Copyright © 2006 by Elsevier, Inc. Thyroid Hormone Synthesis & Secretion Figure 76-2; Guyton & Hall
Copyright © 2006 by Elsevier, Inc. Binding of Thyroid Hormones & Precursors to Thyroglobulin during Hormone Synthesis 3,3’,5’-Triiodothyronine (RT3) 3,5-Diiodotyrosine (DIT) 3,5,3’-Triiodothyronine (T3)
Copyright © 2006 by Elsevier, Inc. Actions of Thyroid Hormones Figure 76-5; Guyton & Hall
Copyright © 2006 by Elsevier, Inc. Metabolic Effects of Thyroid Hormones Parameter ↓ T 3, T 4 ↑ T 3, T 4 Basal metabolic rate ↓ ↑ Carbohydrate metabolism ↓ Gluconeogenesis ↑ Gluconeogenesis ↓ Glycogenolysis ↑ Glycogenolysis Normal serum [glucose] Normal serum [glucose] Protein metabolism ↓ Synthesis ↑ Synthesis ↓ Proteolysis ↑ Proteolysis Muscle wasting Lipid metabolism ↓ Lipogenesis ↑ Lipogenesis ↓ Lipolysis ↑ Lipolysis ↑ Serum [cholesterol] ↓ Serum [cholesterol] Thermogenesis ↓ ↑ Table 48-1, Boron & Boulpaep
Copyright © 2006 by Elsevier, Inc. Hypothalamohypophyseal-Thyroid Axis Hypothalamus Thyrotrope Thyroid T 3, T 4 TRH TRH TSH _ _ + +
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.
Hypothalamohypophyseal-Thyroid Axis in Graves’ Disease Hypothalamus Thyrotrope Thyroid T 3, T 4 TRH TRH TSH _ + _ + TSI +
Copyright © 2006 by Elsevier, Inc. Histology of an Islet of Langerhans of the Pancreas Figure 78-1; Guyton & Hall
Copyright © 2006 by Elsevier, Inc. Metabolic Effects of Glucagon Stimulate Inhibit Glucose Free fatty acids Ketoacids Amino acids Glucose Amino acids Free fatty acids Liver Adipose tissue Ketoacids Glycogen Glucose-P Pyruvate Plasma Berne & Levy, Figure 47-19
Copyright © 2006 by Elsevier, Inc. Approximate Rates of Insulin & Glucagon Secretion at Different Blood Glucose Levels Plasma glucose (mg/dl) 100% 50% 0 100% 50% 0 Insulin Response ( ) Glucagon Response ( )
Copyright © 2006 by Elsevier, Inc. Anatomy of the Parathyroid Glands & Microscopic Appearance of Chief Cells Figure 79-9; Guyton & Hall
Copyright © 2006 by Elsevier, Inc. 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 PTH Actions
Copyright © 2006 by Elsevier, Inc PTH secretion (% maximal rate) Total plasma [Ca 2+ ] (mg/dL) Plasma Calcium Concentration & PTH Secretion
Copyright © 2006 by Elsevier, Inc. Hypocalcemia Disorder Plasma [PTH] Plasma [1,25-(OH) 2 -D 3 ] Urine Bone Plasma [Ca 2+ ] Plasma [Phosphate] Vitamin D deficiency Chronic renal failure (2°) * * Phosphate cAMP Phosphate ( GFR ) * Osteomalacia Resorption * Primary events or disturbances Surgical hypoparathyroidism (2°) * Osteomalacia Resorption cAMP Phosphate Castanzo, Table 9-17
Copyright © 2006 by Elsevier, Inc. Primary Hyperparathyroidism Plasma [PTH] * Plasma [1,25-(OH) 2 -D 3 ] Urine Phosphate Ca 2+ cAMP Bone Resorption Plasma [Ca 2+ ] Plasma [Phosphate] * Primary disturbance Castanzo, Table 9-17