Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition Chapter 20 The Endocrine System

Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition Endocrine System Overview Glands –Pituitary –Thyroid –Parathyroid –Adrenal –Pineal –Thymus Also areas of the –Pancreas –Gonads –Hypothalamus

Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition

Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition Endocrine System Organization Glands – secrete hormones into blood Hormones – chemical messengers Receptor organs – react to chemical messages

Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition Types of Hormones 2 General Categories –Steroid-derived hormones –Amino acid–synthesized hormones Amine Polypeptide

Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition Hormone–Target Cell Specificity Hormones alter cellular reactions of specific target cells by –Stimulating DNA to alter rate of protein synthesis –Altering rate of enzyme activity –Altering plasma membrane transport via second messengers –Inducing secretory activity

Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition Hormone–Receptor Binding A target cell’s activation is dependent upon –Hormone concentration in blood –Sensitivity of receptor for the hormone upregulation downregulation –Number of target cell receptors

Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition Cyclic AMP: The Intracellular Messenger Binding of amine-based hormones to receptor sites may activate the enzyme adenylate cyclase. Adenylate cyclase catalyzes the degradation of ATP to cyclic 3’5’adenosine monophosphate (cyclic AMP). Cyclic AMP then acts to activate protein kinases that alter cellular activity.

Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition

Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition Effects on Enzymes Enzyme activity may be altered in one of three ways. –Stimulate enzyme production –Allosteric modulation –Activating inactive forms of the enzyme

Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition Factors that Determine Hormone Levels Quantity synthesized Rate of catabolism of secretion into blood Quantity of transport proteins present Changes in plasma volume

Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition Patterns of Hormone Release Most respond to peripheral stimuli. Others have a diurnal variation: cycles may be –Daily –Several weeks

Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition Resting and Exercise-Induced Endocrine Secretions Hormones –Immediate response to exercise –Training adaptation

Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition Anterior Pituitary Hormones Releasing factor Proopiomelanocortin (POMC) –Neurotransmitters

Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition Growth Hormone GH or somatotropin Facilitates protein synthesis Stimulated by exercise Modulates metabolic mixture –Stimulates fatty acid release –Inhibits cellular glucose uptake

Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition Insulin-Like Growth Factors IGFs or somatomedins Travel in blood to interact with specific receptors Transport influenced by –Binding proteins in muscle –Nutritional status –Plasma insulin levels

Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition Thyrotropin Thyroid-stimulating hormone (TSH) Regulates hormone secretion by the thyroid Maintains growth and development of thyroid Increases thyroid cell metabolism

Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition

Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition Adrenocorticotropic Hormone ACTH (corticotropin) Increases mobilization of fatty acid from adipose tissue Increases gluconeogenesis Stimulates protein catabolism ACTH increases during exercise depending upon intensity and duration.

Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition Prolactin Prolactin (PRL) initiates and supports milk secretion. –Levels increase at high exercise intensities –May inhibit ovarian function

Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition Gonadotropic Hormones Follicle-stimulating hormone (FSH) –Initiates follicle growth in ovaries –Stimulates estrogen secretion Luteinizing hormone (LH) –Complements FSH action –Stimulates sperm growth and testosterone secretion in testes

Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition Posterior Pituitary Hormones ADH or vasopressin –Increases water retention by kidneys –Stimulated by exercise –Helps conserve body fluids Oxytocin –Important during birthing and nursing

Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition Thyroid Hormones T 3 – triiodothyronine T 4 – thyroxine Increases metabolism of cell Help regulate growth and development Help maintain BP Exercise increases T 4 ~ 35%

Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition Parathyroid Hormones Control blood Ca 2+ levels Its release is influenced by blood concentration of Ca 2+. PTH results in –Bone release of Ca 2+ –Increased calcium reabsorption by kidneys –Increased calcium absorption by intestinal mucosa Exercise may increase PTH.

Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition

Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition Adrenal Hormones Adrenal medulla secretes catecholamines. –Epinephrine Increases glycogenolysis Increases lipolysis –Norepinephrine Increases lipolysis Relative exercise stimulates release intensity.

Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition

Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition Adrenocortical Hormones Mineralocorticoids Glucocorticoids Gonadocorticoids or androgens

Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition Mineralocorticoids: Aldosterone Regulates sodium and K + in extracellular fluid Cellular response to aldosterone is slow > 45 minutes exercise is required to see its effects Influence is mainly on recovery. Renin–angiotensin mechanism

Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition Glucocorticoids Cortisol is the primary glucocorticoid. –Promotes protein breakdown to amino acids –Blunts the effects of insulin –Increases lipolysis –Increases gluconeogenesis –Net effect = mobilization of fuel

Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition Gonadocorticoids Produced in adrenal cortex Similar actions to sex steroids –Dehydroepiandrosterone exerts effects similar to testosterone.

Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition Gonadal Hormones Produced in reproductive glands –Testosterone –Estradiol –Progesterone

Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition Pancreatic Hormones Insulin –Mediates glucose metabolism –Affects fat synthesis –Facilitates protein synthesis –Stimulates glucose transporters (GLUTs) Glucagon –Increases blood glucose –Increases glycogenolysis in the liver

Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition

Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition Metabolic Syndrome X Insulin resistance Hyperinsulinemia Dyslipidemia Hypertension

Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition Insulin Actions and Impaired Glucose Homeostasis Type 1 diabetes –Typically occurs in younger individuals –5 – 10% of all cases –Exercise has greater metabolic effects. Type 2 diabetes –Tends to occur after 40 –Often produces reduced exercise tolerance

Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition Glucagon Secreted by Islets of Langerhans –Stimulates glycogenolysis –Stimulates gluconeogenesis –Release occurs later in exercise.

Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition Other Glands and Hormones Liver –Somatomedins Small intestine –Secretin –Gastrin –Cholecystokinin Hypothalamus –Somatoliberin

Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition Anterior Pituitary Hormones Growth hormone ACTH PRL FSH, LH Testosterone

Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition Gender Differences Women –Exercise may affect FSH and LH levels. Men –Endurance training affects testosterone and PRL levels. –LH and FSH not affected

Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition Posterior Pituitary Hormones ADH Oxytocin

Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition Parathyroid Hormone Enhanced by endurance training

Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition Adrenal Hormones Aldosterone Cortisol Epinephrine and norepinephrine

Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition Pancreatic Hormones Insulin Glucagon

Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition Resistance Training and Endocrine Function Resistance training adaptations affected by –Testosterone –Growth hormone

Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition Opioid Peptides and Exercise Neuropeptides released by the brain ß-lipotropin ß-endorphin Dynorphin –Activate specific opioid receptor sites –Inhibit anterior pituitary hormones, influencing menstrual cycle –May induce the exercise “high”

Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition Exercise, Infectious Illness, Cancer, and Immune Response The influence of exercise on immune function generally follows a J-shaped curve. Exercise in the optimal range seems to aid immune function. Overtraining may impair immune function.

Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition