Endocrine Physiology

314 Pages·2013·9.451 MB·English

by  Patricia Molina

a LANGE medical book
Endocrine
Physiology
fourth edition
Patricia E. Molina, MD, PhD
Richard Ashman, PhD Professor
Head, Department of Physiology
Louisiana State University Health Sciences Center
New Orleans, Louisiana
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To my friend, colleague, and husband,
Miguel F. Molina, MD, for his
unconditional support and constant
reminder of what is really
important in life.
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Contents
Preface vii
Chapter 1 General Principles of Endocrine Physiology 1
The Endocrine System: Physiologic Functions
and Components / 1
Hormone Chemistry and Mechanisms of Action / 3
Hormone Cellular Effects / 8
Hormone Receptors and Signal Transduction / 8
Control of Hormone Release / 14
Assessment of Endocrine Function / 19
Chapter 2 Th e Hypothalamus and Posterior Pituitary Gland 25
Functional Anatomy / 27
Hormones of the Posterior Pituitary / 32
Chapter 3 Anterior Pituitary Gland 49
Functional Anatomy / 49
Hypothalamic Control of Anterior Pituitary
Hormone Release / 51
Hormones of the Anterior Pituitary / 52
Diseases of the Anterior Pituitary / 68
Chapter 4 Th yroid Gland 73
Functional Anatomy / 73
Regulation of Biosynthesis, Storage,
and Secretion of Thyroid Hormones / 76
Diseases of Thyroid Hormone Overproduction
and Undersecretion / 88
Evaluation of the Hypothalamic-pituitary-Thyroid Axis / 93
Chapter 5 Parathyroid Gland and Ca2+ and PO– Regulation 99
4
Functional Anatomy / 100
Parathyroid Hormone Biosynthesis and Transport / 100
Parathyroid Hormone Target Organs and
Physiologic Effects / 103
Calcium Homeostasis / 111
Diseases of Parathyroid Hormone Production / 123
Chapter 6 Adrenal Gland 129
Functional Anatomy and Zonation / 130
Hormones of the Adrenal Cortex / 132
Hormones of the Adrenal Medulla / 151
v
vi / CONTENTS
Chapter 7 Endocrine Pancreas 163
Functional Anatomy / 163
Pancreatic Hormones / 164
Diseases Associated with Pancreatic Hormones / 178
Complications of Diabetes / 181
Chapter 8 Male Reproductive System 187
Functional Anatomy / 188
Gonadotropin Regulation of Gonadal Function / 190
Gonadal Function / 194
Physiologic Effects of Androgens at Target Organs / 198
Neuroendocrine and Vascular
Control of Erection and Ejaculation / 206
Diseases of Testosterone Excess or Deficiency / 207
Chapter 9 Female Reproductive System 213
Functional Anatomy / 214
Gonadotropin Regulation of Ovarian Function / 216
Ovarian Hormone Synthesis / 217
Ovarian Cycle / 220
Endometrial Cycle / 226
Physiologic Effects of Ovarian Hormones / 228
Age-Related Changes in the
Female Reproductive System / 241
Contraception and the Female Reproductive Tract / 244
Diseases of Overproduction and
Undersecretion of Ovarian Hormones / 245
Chapter 10 Endocrine Integration of Energy
and Electrolyte Balance 249
Neuroendocrine Regulation of Energy Storage,
Mobilization, and Utilization / 250
Electrolyte Balance / 265
Neuroendocrine Regulation of the Stress Response / 275
Appendix Normal Values of Metabolic Parameters
and Tests of Endocrine Function 281
Table A. Plasma and serum values / 281
Table B. Urinary levels / 283
Answers to Study Questions 285
Index 293
Preface
Th is fourth edition of Endocrine Physiology provides comprehensive coverage of
the fundamental concepts of hormone biological action. Th e content has been
revised and edited to enhance clarity and understanding, and illustrations have
been added and annotated to highlight the principal concepts in each chapter.
In addition, the answers to the test questions at the end of the chapter have been
expanded to include explanations for the correct answers.
Th e concepts herein provide the basis by which fi rst- and second-year medical
students will better grasp the physiologic mechanisms involved in neuroendo-
crine regulation of organ function. Th e information presented is also meant to
serve as a reference for residents and fellows. Th e objectives listed at the beginning
of each chapter follow those established and revised in 2012 by the American
Physiological Society for each hormone system and are the topics tested in Step I
of the United States Medical Licensing Examination (USMLE).
As with any discipline in science and medicine, our understanding of endo-
crine molecular physiology has changed and continues to evolve to encompass
neural, immune, and metabolic regulation and interaction. Th e suggested read-
ings have been updated to provide guidance for more in-depth understanding of
the concepts presented. Th ey are by no means all inclusive, but were found by the
author to be of great help in putting the information together.
Th e fi rst chapter describes the organization of the endocrine system, as well
as general concepts of hormone production and release, transport and metabolic
fate, and cellular mechanisms of action. Chapters 2–9 discuss specifi c endocrine
systems and describe the specifi c hormone produced by each system in the context
of the regulation of its production and release, the target physiologic actions, and
the clinical implications of either its excess or defi ciency. Each chapter starts with
a short description of the functional anatomy of the organ, highlighting important
features pertaining to circulation, location, or cellular composition that have a
direct eff ect on its endocrine function. Understanding the mechanisms underly-
ing normal endocrine physiology is essential in order to understand the transi-
tion from health to disease and the rationale involved in pharmacological, surgical,
or genetic interventions. Th us, the salient features involved in determination of
abnormal hormone production, regulation or function are also described. Each
chapter includes simple diagrams illustrating some of the key concepts presented
and concludes with sample questions designed to test the overall assimilation of
the information given. Th e key concepts provided in each chapter correspond to
the particular section of the chapter that describes them. Chapter 10 illustrates
how the individual endocrine systems described throughout the book dynamically
interact in maintaining homeostasis.
As with the previous editions of this book; the modifi cations are driven by
the questions raised by my students during lecture or when studying for an
vii
viii / PREFACE
examination. Th ose questions have been the best way of gauging the clarity of the
writing and they have also alerted me when unnecessary description complicated
or obscured the understanding of a basic concept. Improved learning and under-
standing of the concepts by our students continues to be my inspiration. I would
like to thank them, as well as all the faculty of the Department of Physiology at
LSUHSC for their dedication to the teaching of this discipline.
General Principles of
1
Endocrine Physiology
OBJECTIVES
Y Contrast the terms endocrine , paracrine , and autocrine .
Y Defi ne the terms hormone , target cell , and receptor .
Y Understand the major diff erences in mechanisms of action of peptides, steroids,
and thyroid hormones.
Y Compare and contrast hormone actions exerted via plasma membrane receptors
with those mediated via intracellular receptors.
Y Understand the role of hormone-binding proteins.
Y Understand the feedback control mechanisms of hormone secretion.
Y Explain the eff ects of secretion, degradation, and excretion on plasma hormone
concentrations.
Y Understand the basis of hormone measurements and their interpretation.
Th e function of the endocrine system is to coordinate and integrate cellular activ-
ity within the whole body by regulating cellular and organ function throughout
life and maintaining h omeostasis . Homeostasis, or the maintenance of a constant
internal environment, is critical to ensuring appropriate cellular function.
THE ENDOCRINE SYSTEM: PHYSIOLOGIC
FUNCTIONS AND COMPONENTS
Some of the key functions of the endocrine system include:
• Regulation of sodium and water balance and control of blood volume and
pressure
• Regulation of calcium and phosphate balance to preserve extracellular fl uid
concentrations required for cell membrane integrity and intracellular signaling
• Regulation of energy balance and control of fuel mobilization, utilization, and
storage to ensure that cellular metabolic demands are met
1