Учебник по Физиология (английски език)

Physiology

Physiology
FIFTH EDITION
Linda S. Costanzo, PhD
Professor of Physiology and Biophysics
Virginia Commonwealth University School of Medicine
Richmond, Virginia

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160 Johon0F ISBN: 978-1-4557-0847-5
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ISBN: 978-1-4557-0847-5
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v
To
Heinz Valtin and Arthur C. Guyton,
who have written so well for students of physiology
Richard, Dan, Rebecca, Sheila, Elise, and Max,
who make everything worthwhile

vii
Preface
Physiology is the foundation of medical practice. A firm grasp of its principles is essential
for the medical student and the practicing physician. This book is intended for students
of medicine and related disciplines who are engaged in the study of physiology. It can
be used either as a companion to lectures and syllabi in discipline-based curricula or as
a primary source in integrated or problem-based curricula. For advanced students, the
book can serve as a reference in pathophysiology courses and in clinical clerkships.
In the fifth edition of this book, as in the previous editions, the important concepts
in physiology are covered at the organ system and cellular levels. Chapters 1 and 2
present the underlying principles of cellular physiology and the autonomic nervous
system. Chapters 3 through 10 present the major organ systems: neurophysiology and
cardiovascular, respiratory, renal, acid-base, gastrointestinal, endocrine, and reproduc-
tive physiology. The relationships between organ systems are emphasized to underscore
the integrative mechanisms for homeostasis.
This edition includes the following features designed to facilitate the study of
physiology:
♦ Text that is easy to read and concise: Clear headings orient the student to the orga-
nization and hierarchy of the material. Complex physiologic information is presented
systematically, logically, and step-wise. When a process occurs in a specific sequence,
the steps are numbered in the text and often correlate with numbers shown in a
figure. Bullets are used to separate and highlight the features of a process. Rhetorical
questions are posed throughout the text to anticipate the questions that students may
be asking; by first contemplating and then answering these questions, students learn
to explain difficult concepts and rationalize unexpected or paradoxical findings. Refer-
ences at the end of each chapter direct the student to monographs, texts, review
articles, and classic papers that offer further detail or historical perspective. Chapter
summaries provide a brief overview.
♦ Tables and illustrations that can be used in concert with the text or, because they
are designed to stand alone, as a review: The tables summarize, organize, and make
comparisons. Examples are (1) a table that compares the gastrointestinal hormones
with respect to hormone family, site of and stimuli for secretion, and hormone
actions; (2) a table that compares the pathophysiologic features of disorders of Ca
2+

homeostasis; and (3) a table that compares the features of the action potential in
different cardiac tissues. The illustrations are clearly labeled, often with main head-
ings, and include simple diagrams, complex diagrams with numbered steps, and flow
charts.
♦ Equations and sample problems that are integrated into the text: All terms and units
in equations are defined, and each equation is restated in words to place it in a
physiologic context. Sample problems are followed by complete numerical solutions
and explanations that guide the student through the proper steps in reasoning; by

viii •  Preface
following the steps provided, students acquire the skills and confidence to solve
similar or related problems.
♦ Clinical physiology presented in boxes: Each box features a fictitious patient with a
classic disorder. The clinical findings and proposed treatment are explained in terms
of underlying physiologic principles. An integrative approach to the patient is used
to emphasize the relationships between organ systems. For example, the case of
type I diabetes mellitus involves a disorder not only of the endocrine system but also
of the renal, acid-base, respiratory, and cardiovascular systems.
♦ Practice questions in “Challenge Yourself” sections at the end of each chapter: Prac-
tice questions, which are designed for short answers (a word, a phrase, or a numerical
solution), challenge the student to apply principles and concepts in problem solving
rather than to recall isolated facts. The questions are posed in varying formats and
are given in random order. They will be most helpful when used as a tool after study-
ing each chapter and without referring to the text. In that way, the student can
confirm his or her understanding of the material and can determine areas of weak-
ness. Answers are provided at the end of the book.
♦ Abbreviations and normal values presented in appendices. As students refer to and
use these common abbreviations and values throughout the book, they will find that
they become second nature.
This book embodies three beliefs that I hold about teaching: (1) even complex infor-
mation can be transmitted clearly if the presentation is systematic, logical, and presented
step-wise; (2) the presentation can be just as effective in print as in person; and
(3) beginning medical students wish for nonreference teaching materials that are accu-
rate and didactically strong but without the details that primarily concern experts. In
essence, a book can “teach” if the teacher’s voice is present, if the material is carefully
selected to include essential information, and if great care is paid to logic and sequence.
This text offers a down-to-earth and professional presentation written to students and
for students.
I hope that the readers of this book enjoy their study of physiology. Those who learn
its principles well will be rewarded throughout their professional careers!
Linda S. Costanzo

ix
Acknowledgments
I gratefully acknowledge the contributions of Elyse O’Grady, Andrea Vosburgh, and
John Casey at Elsevier in preparing the fifth edition of Physiology. The artist, Matthew
Chansky, revised existing figures and created new figures—all of which beautifully
complement the text.
Colleagues at Virginia Commonwealth University have faithfully answered my ques-
tions, especially Drs. Clive Baumgarten, Diomedes Logothetis, Roland Pittman, and
Raphael Witorsch. Sincere thanks also go to the medical students worldwide who have
generously written to me about their experiences with earlier editions of the book.
My husband, Richard, our children, Dan and Rebecca, our daughter-in-law, Sheila,
and our grandchildren, Elise and Max, have provided enthusiastic support and unquali-
fied love, which give the book its spirit.

1
Cellular Physiology
Volume and Composition of Body Fluids, 1
Characteristics of Cell Membranes, 4
Transport across Cell Membranes, 5
Diffusion Potentials and Equilibrium
Potentials, 14
Resting Membrane Potential, 18
Action Potentials, 19
Synaptic and Neuromuscular Transmission, 24
Skeletal Muscle, 33
Smooth Muscle, 39
Summary, 43
Challenge Yourself, 43
Understanding the functions of the organ systems
requires profound knowledge of basic cellular mecha-
nisms. Although each organ system differs in its overall
function, all are undergirded by a common set of
physiologic principles.
The following basic principles of physiology are
introduced in this chapter: body fluids, with particular
emphasis on the differences in composition of intracel-
lular fluid and extracellular fluid; creation of these
concentration differences by transport processes in cell
membranes; the origin of the electrical potential differ-
ence across cell membranes, particularly in excitable
cells such as nerve and muscle; generation of action
potentials and their propagation in excitable cells;
transmission of information between cells across syn-
apses and the role of neurotransmitters; and the mecha-
nisms that couple the action potentials to contraction
in muscle cells.
These principles of cellular physiology constitute a
set of recurring and interlocking themes. Once these
principles are understood, they can be applied and integrated into the function of each
organ system.
VOLUME AND COMPOSITION OF BODY FLUIDS
Distribution of Water in the Body Fluid Compartments
In the human body, water constitutes a high proportion of body weight. The total
amount of fluid or water is called total body water, which accounts for 50% to 70% of
body weight. For example, a 70-kilogram (kg) man whose total body water is 65% of
his body weight has 45.5kg or 45.5 liters (L) of water (1kg water ≈ 1L
general, total body water correlates inversely with body fat. Thus, total body water is a higher percentage of body weight when body fat is low and a lower percentage when body fat is high. Because females have a higher percentage of adipose tissue than males, they tend to have less body water. The distribution of water among body fluid compart-
ments is described briefly in this chapter and in greater detail in Chapter 6.
Total body water is distributed between two major body fluid compartments: intracel-
lular fluid (ICF) and extracellular fluid (ECF) (Fig. 1-1). The ICF is contained within the
cells and is two thirds of total body water; the ECF is out