THIRD EDITION HUMAN PHYSIOLOGY AN INTEGRATED APPROACH Dee

THIRD EDITION HUMAN PHYSIOLOGY AN INTEGRATED APPROACH Dee Unglaub Silverthorn, Ph. D. Chapter 23 Endocrine Control of Growth and Metabolism Power. Point® Lecture Slide Presentation by Dr. Howard D. Booth, Professor of Biology, Eastern Michigan University Copyright © 2004 Pearson Education, Inc. , publishing as Benjamin Cummings

About this Chapter • How several key hormone pathways influence metabolism • How cortisol is produced & regulated; how it impacts many tissues • How thyroid hormones are regulated and their effect on targets • The role of growth hormone in growth & development • Calcium metabolism and its role in bones and cell regulations Copyright © 2004 Pearson Education, Inc. , publishing as Benjamin Cummings

Endocrine Control in Review • Hypothalamic – pituitary: feedback loop & trophic control • Hormones can have receptors on many diverse tissues • Usually initiating protein change or synthesis in target cells • Problems come from too much or too little hormone Copyright © 2004 Pearson Education, Inc. , publishing as Benjamin Cummings

Adrenal Cortex: Steroid Hormone Production Figure 23 -2: Synthesis pathways of steroid hormones Copyright © 2004 Pearson Education, Inc. , publishing as Benjamin Cummings

Cortisol Effects: Body Responses to Stress • Permissive effect on glucagon • Memory, learning & mood • Gluconeogenesis • Skeletal muscle breakdown • Lipolysis, calcium balance • Immune depression • Circadian rhythms Copyright © 2004 Pearson Education, Inc. , publishing as Benjamin Cummings

Cortisol Effects: Body Responses to Stress Figure 23 -4: Circadian rhythm of cortisol secretion Copyright © 2004 Pearson Education, Inc. , publishing as Benjamin Cummings

Control of Cortisol Secretion: Feedback Loops • External stimuli • Hypothalamic • Anterior Pituitary • Adrenal cortex • Tissues Copyright © 2004 Pearson Education, Inc. , publishing as Benjamin Cummings Figure 23 -3: The control pathway for cortisol

Endocrine Control: Three Levels of Integration Copyright © 2004 Pearson Education, Inc. , publishing as Benjamin Cummings Figure 7 -13: Hormones of the hypothalamic-anterior pituitary pathway

Cortisol: Role in Diseases and Medication • Use as immunosuppressant • Hyperimmune reactions (bee stings) • Serious side effects • Hypercortisolism (Cushing's syndrome) • Tumors (pituitary or adrenal) • Iatrogenic (physician caused) • Hypocortisolism (Addison's disease) Copyright © 2004 Pearson Education, Inc. , publishing as Benjamin Cummings

Thyroid Gland: Hormones and Iodine Metabolism • C-cells – calcitonin (covered later) • Follicle cells • Amine hormones: • thyroxine, T 1, T 2 & T 3 • growth • metabolism • Thermogenic Copyright © 2004 Pearson Education, Inc. , publishing as Benjamin Cummings

Effects of Thyroid Hormone • TH is concerned with: • Glucose oxidation • Increasing metabolic rate • Heat production • TH plays a role in: • Maintaining blood pressure • Regulating tissue growth • Developing skeletal and nervous systems • Maturation and reproductive capabilities Copyright © 2004 Pearson Education, Inc. , publishing as Benjamin Cummings

Thyroid Hormone • Thyroid hormone – the body’s major metabolic hormone • Consists of two closely related iodine-containing compounds • T 4 – thyroxine; has two tyrosine molecules plus four bound iodine atoms • T 3 – triiodothyronine; has two tyrosines with three bound iodine atoms Copyright © 2004 Pearson Education, Inc. , publishing as Benjamin Cummings

Thyroid Gland: Hormones and Iodine Metabolism Figure 23 -7 b: The thyroid gland Copyright © 2004 Pearson Education, Inc. , publishing as Benjamin Cummings

Thyroxine and its precursors: Structure & Synthesis Figure 23 -8: Thyroid hormones are made from tyrosine and iodine Copyright © 2004 Pearson Education, Inc. , publishing as Benjamin Cummings

Thyroxine and its precursors: Structure & Synthesis Figure 23 -9: Thyroid hormone synthesis Copyright © 2004 Pearson Education, Inc. , publishing as Benjamin Cummings

Synthesis of Thyroid Hormone • Thyroglobulin is synthesized and discharged into the lumen • Iodides (I–) are actively taken into the cell, oxidized to iodine (I 2), and released into the lumen • Iodine attaches to tyrosine, mediated by peroxidase enzymes, forming T 1 (monoiodotyrosine, or MIT), and T 2 (diiodotyrosine, or DIT) • Iodinated tyrosines link together to form T 3 and T 4 • Colloid is then endocytosed and combined with a lysosome, where T 3 and T 4 are cleaved and diffuse into the bloodstream Copyright © 2004 Pearson Education, Inc. , publishing as Benjamin Cummings

Transport and Regulation of TH • T 4 and T 3 bind to thyroxine-binding globulins (TBGs) produced by the liver • Both bind to target receptors, but T 3 is ten times more active than T 4 • Peripheral tissues convert T 4 to T 3 • Mechanisms of activity are similar to steroids • Regulation is by negative feedback • Hypothalamic thyrotropin-releasing hormone (TRH) can overcome the negative feedback Copyright © 2004 Pearson Education, Inc. , publishing as Benjamin Cummings

T 3 & T 4 Control Pathways & Diseases from Malfunction • Hypothalamus • Anterior Pituitary • Thyroid • Hypothyroidism • Goiter (TSH ) • Grave's disease Copyright © 2004 Pearson Education, Inc. , publishing as Benjamin Cummings

Copyright © 2004 Pearson Education, Inc. , publishing as Benjamin Cummings

T 3 & T 4 Control Pathways & Diseases from Malfunction Copyright © 2004 Pearson Education, Inc. , publishing as Benjamin Cummings Figure 23 -12: Thyroid hormone pathway

Growth Hormone (GH): Functions & Malfunctions • Polypeptide H from hypothalamus/anterior pituitary • growth (with T 4, sex Hs, paracrines) • metabolism • protein & bone synthesis • Regulation – hypothalamus • Dwarfism • Acromegaly Copyright © 2004 Pearson Education, Inc. , publishing as Benjamin Cummings

Metabolic Action of Growth Hormone Copyright © 2004 Pearson Education, Inc. , publishing as Benjamin Cummings Figure 16. 6

Growth Hormone (GH): Functions & Malfunctions Copyright © 2004 Pearson Education, Inc. , publishing as Benjamin Cummings Figure 23 -16: Growth hormone pathway

Multiple Hormones Can Target a Cell/Tissue • Growth H • Somatomedins • Thyroxin • All have receptors on many tissues • Stimulate pathways for growth Figure 7 -17: A complex endocrine pathway Copyright © 2004 Pearson Education, Inc. , publishing as Benjamin Cummings

Bone Growth and Calcium Metabolism • Epiphyseal plate – new bone growth site • Chondrocytes, osteoblasts & calcification build bone Copyright © 2004 Pearson Education, Inc. , publishing as Benjamin Cummings

Bone Growth and Calcium Metabolism Figure 23 -19: Bone growth at the epiphyseal plate Copyright © 2004 Pearson Education, Inc. , publishing as Benjamin Cummings

Calcium Metabolism: • Maintain [plasma]: from diet, from bone "storage", recycled • Key roles: muscle contraction, bone support, cell signaling Copyright © 2004 Pearson Education, Inc. , publishing as Benjamin Cummings

Copyright © 2004 Pearson Education, Inc. , publishing as Benjamin Cummings

Calcium Metabolism: Figure 23 -20: Calcium balance in the body Copyright © 2004 Pearson Education, Inc. , publishing as Benjamin Cummings

Control of Calcium Balance & Metabolism • Parathyroid H • Calcitrol • Vitamin D • Sun/diet • Calcitonin • Thyroid • C-cells • (Phosphate balance) Copyright © 2004 Pearson Education, Inc. , publishing as Benjamin Cummings Figure 23 -23: Endocrine control of calcium balance

Copyright © 2004 Pearson Education, Inc. , publishing as Benjamin Cummings

Copyright © 2004 Pearson Education, Inc. , publishing as Benjamin Cummings

Osteoporosis: Disease of Bone Growth & Calcium Metabolism • Bone reabsorption exceeds deposition • Osteoclasts mobilize Ca++ to plasma • Factors: inadequate Ca++ intake, genes, hormones, smoking Copyright © 2004 Pearson Education, Inc. , publishing as Benjamin Cummings Figure 23 -21: Osteoclasts are responsible for bone resorption

Summary • In addition to insulin and glucagon, metabolism is influenced by hormones from adrenal, thyroid, parathyroid and hypothalamus • Cortisol catabolic activities responding to stress • Growth H anabolic activities to promote growth • PTH, cacitrol, & calcitonin balance plasma [Ca++] for bone synthesis, muscle contraction, & cell signaling • Endocrine diseases result from pathway or glandular hypo or hyper secretion Copyright © 2004 Pearson Education, Inc. , publishing as Benjamin Cummings