Human Physiology: An Integrated Approach, Global Edition

983 Pages·2018·66.957 MB·English

by  Dee Silverthorn

Untitled-1 1 7/17/18 5:06 PM
Contents in Brief
UNIT 1 Basic Cell Processes: Integration
and Coordination
1 Introduction to Physiology 37
2 Molecular Interactions 64
3 Compartmentation: Cells and Tissues 94
4 Energy and Cellular Metabolism 128
5 Membrane Dynamics 157
6 Communication, Integration, and Homeostasis 200
UNIT 2 Homeostasis and Control
7 Introduction to the Endocrine System 230
8 Neurons: Cellular and Network Properties 259
9 The Central Nervous System 307
10 Sensory Physiology 343
11 Efferent Division: Autonomic and Somatic Motor Control 391
12 Muscles 410
13 Integrative Physiology I: Control of Body Movement 450
UNIT 3 Integration of Function
14 Cardiovascular Physiology 468
15 Blood Flow and the Control of Blood Pressure 512
16 Blood 546
17 Mechanics of Breathing 568
18 Gas Exchange and Transport 598
19 The Kidneys 623
20 Integrative Physiology II: Fluid and Electrolyte Balance 654
UNIT 4 Metabolism, Growth, and Aging
21 The Digestive System 690
22 Metabolism and Energy Balance 728
23 Endocrine Control of Growth and Metabolism 764
24 The Immune System 790
25 Integrative Physiology III: Exercise 823
26 Reproduction and Development 837
Silverthorn_08_129225954X_ifc_Final.indd 1 26/06/18 5:39 PM
Strategies for Success
Top Ten Ways to Word Roots for Physiology
Succeed in Classes that
Simplify physiology and medicine by learning Latin and
Use Active Learning Greek word roots. The list below has some of the most
common ones.
By Marilla Svinicki, Ph.D., former Director of the Using the list, can you figure out what hyperkalemia
University of Texas Center for Teaching Effectiveness means?*
1. Make the switch from an authority-based a- or an- without, absence hypo- beneath or deficient
conception of learning to a self-regulated anti- against inter- between
conception of learning. Recognize and accept -ase signifies an enzyme intra- within
your own responsibility for learning. auto self -itis inflammation of
bi- two kali- potassium
2. Be willing to take risks and go beyond what is
brady- slow leuko- white
presented in class or the text.
cardio- heart lipo- fat
3. Be able to tolerate ambiguity and frustration cephalo- head lumen inside of a hollow tube
in the interest of understanding. cerebro- brain -lysis split apart or rupture
contra- against macro- large
4. See errors as opportunities to learn rather than
-crine a secretion micro- small
failures. Be willing to make mistakes in class or in
crypt- hidden mono- one
study groups so that you can learn from them.
cutan- skin multi- many
5. Engage in active listening to what’s happening in
-cyte or cyto- cell myo- muscle
class.
de- without, lacking oligo- little, few
6. Trust the instructor’s experience in designing di- two para- near, close
class activities and participate willingly if not dys- difficult, faulty patho-, -pathy related to
enthusiastically. -elle small disease
-emia in the blood peri- around
7. Be willing to express an opinion or hazard a
endo- inside or within poly- many
guess.
epi- over post- after
8. Accept feedback in the spirit of learning rather erythro- red pre- before
than as a reflection of you as a person. exo- outside pro- before
extra- outside pseudo- false
9. Prepare for class physically, mentally, and
gastro- stomach re- again
materially (do the reading, work the problems,
-gen, -genie produce retro- backward or behind
etc.).
gluco-, glyco- sugar or sweet semi-half
10. Provide support for your classmate’s attempts to hemi- half sub- below
learn. The best way to learn something well is to
hemo- blood super- above, beyond
teach it to someone who doesn’t understand.
hepato- liver supra- above, on top of
homo- same tachy- rapid
Dr. Dee’s Eleventh Rule: hydro- water trans- across, through
DON’T PANIC! Pushing yourself beyond the comfort hyper- above or excess
zone is scary, but you have to do it in order to
* Hyper = excess, kali = potassium, -emia = in the blood,
improve.
or elevated blood potassium
A01_SILV9543_08_GE_FM.indd 1 09/07/2018 13:53
Owner’s Manual

Welcome to Human Pattern recognition is important for all healthcare
Physiology! As you professionals, so you can begin to develop this skill by
begin your study of learning the key concepts of physiology that repeat
the human body, one over and over as you study different organ systems.
of your main tasks Chapter 1 includes two special Focus On features: one
will be to construct on concept mapping, a study strategy that is also used
for yourself a global for decision-making in the clinics, and one on construct-
view of the body, its ing and interpreting graphs. The Running Problem
systems, and the many in Chapter 1 introduces you to effective ways to find
processes that keep the systems working. This ”big information on the Internet.
picture” is what physiologists call the integration of Be sure to look for the Essentials and Review fig-
systems, and it is a key theme in this book. To integrate ures throughout the book. These figures distill the
information, however, you must do more than simply basics about a topic onto one or two pages, much as
memorize it. You need to truly understand it and be the Anatomy Summaries do. My students tell me they
able to use it to solve problems that you have never find them particularly useful for review when there
encountered before. If you are headed for a career in isn’t time to go back and read all the text.
the health professions, you will do this in the clinics. If We have also retained the four approaches to
you plan a career in biology, you will solve problems in learning physiology that proved so popular since this
the laboratory, field, or classroom. Analyzing, synthe- book was first published in 1998.
sizing, and evaluating information are skills you need
1. Cellular and Molecular Physiology
to develop while you are in school, and I hope that the
features of this book will help you with this goal. Most physiological research today is being done at
One of my aims is to provide you not only with in- the cellular and molecular level, and there have been
formation about how the human body functions but many exciting developments in molecular medicine and
also with tips for studying and problem solving. Many physiology in the 10 years since the first edition. For ex-
of these study aids have been developed with the input ample, now scientists are paying more attention to pri-
3.3 Intracellular Compartments 69
of my students, so I think you may find them particu- mary cilia, the single cilium that
FIG. 3.5 Cilia and flagella
larlyO hne tlphfeu flo.llowing pages, I have put together a brief (a) Cilia on surface of respiratory epithelium oPrci(cbm)u Cmiilcraiaro sartun bydou fl leanscg seiu llrlamroi huaanvdoe i n9ag sp arat cire es ncot fr aetl phlaliro.s uogf hth(tc) Tecthreeo a btbee sa poftliunigdld oamf yocyvilie.a m aenndt .flagella CHAPTER
Fluid movement
3
tour of the special features of the book, especially those a role in some kidney and other
that you may not have encountered previously in text- diseases. Look for similar links
books. Please take a few minutes to read about them so between molecular and cellulaFlarge llum
Microtubules
that you can make optimum use of the book as you study. biology, physiology, and medi-
Fluid movement
Each chapter begins with a list of Learning Out- SEM × 1500 cine througCilhiumout the book.
This image was taken with a scanning electron
comes to guide you as you read the chapter. Within the microscope (SEM) and then color enhanced. The
2sp.e cimPenhs preyparsedi foor sclanoningg eleyctro n amicsros -a Dynamic CFell imeemblradne
chapters look for the Running Problem, Phys in Action, copy are not sectioned. The whole specimen is
coated with an electron-dense material, and then
bombarded with electron beams. Because some Cilia
and Try It! activities. Phys in Action are online video clips Pofh they eslecitroonsl aore grefleyct edi sba cak, a tdhreye-namic discipline, with numerous
dimensional image of the specimen is created.
that I created with the assistance of some of my stu- unanswered questions that merit further investigation
dents. Look for anTdhe rcyetosskeeleatonr hcash at .le aMst fivae inmpyor taont ffu ntcthiones. ”facts5”. M povremeesnet. Tnhet ceytodsk elietnon htelhps icsell s tmeovex. Fto r example,
the cytoskeleton helps white blood cells squeeze out of blood
1. Cell shape. The protein scaffolding of the cytoskeleton pro-
the references to arevid ers emeachlanliyca l ostrenngtlhy to tohe ucelrl a ncd uin sromree cenlls tpl atysh ane orievses,se lss aond hyelpos gurow isngh neorveu celllds se nbd oeut long extensions as
Play Phys in Action important role in determining the shape of the cell. Figure 3.4b they elongate. Cilia and flagella on the cell membrane are able to
move because of their microtubule cytoskeleton. Special motor
@Mastering Anatomy & Physiology Mastering A&P preshpowsa horwe cydtos kteloeta l fcibhersa henlp sgupepor ty moicruovril lim {micero-n, tal mprooteinds faecillitsat e amosve mnenet awnd i ntirnaceflluolarr tr-ansport by using
small+villus, tuft of hair}, fingerlike extensions of the cell mem- energy from ATP to slide or step along cytoskeletal fibers.
in the figures mabrtanieo thnat i necremase tehe rsugrfaece asr eaf froro abmsorpt iosnc oif emantertialis.fic research.
2. Internal organization. Cytoskeletal fibers stabilize the
positions of organelles. Figure 3.4b illustrates organelles held Motor Proteins Create Movement
with associated Phys in Action clips, and watch Kevin EMin plaEce bRy thGe cIytNoskeGleto n.C NoOte, hNoweCver, EthaPt thiTs figSure is Motor proteins are proteins that convert stored energy into
and Michael as they demonstrate physiology in action. oarnrlayn ag esnmaepnsth aont do fc oomnep omsiotimone notf ian ctehlel acreel ld’sy lnifaem. Tich, ec hinantegriinogr datieredc wteidth m thoev ceymtoesnkte. leTtohnre: em gyroosiunpss, koifn emsinotso, ar npdr odtyenineisn as.r eA lal stshorceie-
from minute to minute in response to the needs of the cell, groups use energy stored in ATP to propel themselves along cyto-
just as the inside of the walled city is always in motion. One skeleton fibers.
disadvantage of the static illustrations in textbooks is that they Myosins bind to actin fibers and are best known for their
are unable to represent movement and the dynamic nature of role in muscle contraction (Chapter 12). Kinesins and dyneins
many physiological processes. assist the movement of vesicles along microtubules. Dyneins also
3. Intracellular transport. The cytoskeleton helps transport associate with the microtubule bundles of cilia and flagella to help
materials into the cell and within the cytoplasm by serving as create their whiplike motion.
an intracellular “railroad track” for moving organelles. This
function is particularly important in cells of the nervous sys-
tem, where material must be transported over intracellular
distances as long as a meter. Concept Check
4. Assembly of cells into tissues. Protein fibers of the cyto- 5. Name the three sizes of cytoplasmic protein fibers.
A01_SILV9543_08_GE_FM.indd 2 skeleton connect with protein fibers in the extracellular space, 6. How would the absence of a flagellum affect a sperm cell0?9/07/2018 13:53
linking cells to one another and to supporting material outside 7. What is the difference between cytoplasm and cytosol?
the cells. In addition to providing mechanical strength to the 8. What is the difference between a cilium and a flagellum?
tissue, these linkages allow the transfer of information from 9. What is the function of motor proteins?
one cell to another.
M03_SILV5197_08_SE_C03.indd 69 9/12/17 2:35 PM
How to Use this Book
4 CHAPTER 1 Introduction to Physiology
FIG. 1.2 Organ systems of the human body and their integrat3ion. An Emphasis on Integration Also, be sure to look at the back of the text, where
FIG. 1.2 Organ Systems of the Human Body and their Integration we have combined the index and glossary to save time
The organ systems
System Name Includes Representative Functions The Integration between Systems of the Body
when you are looking up unfamiliar words. The appen-
Circulatory Heart, blood Transport of materials between all Integumentary System of the body do not
vessels, blood cells of the body dices have the answers to the Concept Check questions,
Respiratory work in isolation,
Digestive Sinttoemstainceh,, liver, Cthoant vcearnsi obne otrfa fnosopdo irntetod pinatroti cthlees system Figure and Graph Questions, and end-of-chapter ques-
pancreas body; elimination of some wastes Nervous although we study
system tions, as well as
Endocrine Thyroid gland, Coordination of body function them one at a time.
adrenal gland through synthesis and release of
regulatory molecules reviews of physics,
To emphasize the
Immune Thymus, spleen, Defense against foreign Endocrine logarithms, and
lymph nodes invaders Digestive system integrative nature
Integumentary Skin Penrovtierocntimone nfrtom external system Circsuylasttoemry of physiology, three basic genetics. A
periodic table of
Musculoskeletal Skeletal mus- Support and movement chapters (Chapters
cles, bone
the elements, dia-
Nervous Brain, spinal Coordination of body function 13, 20, and 25) focus
cord through electrical signals and Musculoskeletal grams of anatomi-
release of regulatory molecules system on how the physi-
Urinary
Reproductive Ovaries and Perpetuation of the species system cal positions of
uterus, testes ological processes of
Respiratory Lungs, airways Exchange of oxygen and carbon Rsyesptreomductive the body, and ta-
dioxide between the internal and multiple organ sys-
external environments bles with conver-
This schematic figure indicates relationships between tems coordinate with
Urinary Kidneys, bladder Maintenance of water and systems of the human body. The interiors of some sions and normal
seonlvuirteosn mine tnhte; winatesrten arlemoval eahecxotlhelorwn a ool regntavnhirso n(esmhorewn,t n.e in swphitee) acrei paarlt loyf th ewhen homeostasis is challenged.
values of blood components are included at the back
or through a break in the skin. In addition, immune tissues are 4T.h Aese prFocoessc muapss a reo alsno c aPlledr folow bchalrtes, amnd the yS areo freqluventilyn g of the book. Take a few minutes to look at all these
closely associated with the circulatory system. used in health care. You will be able to practice mapping with spe-
features so that you can make optimum use of them.
Traditionally, physiology courses and books are organized by cial end-of-chapter questions throughout the book.
organ system. Students study cardiovascular physiology and regu- One of the most valuable life skills students should
lation of blood pressure in one chapter, and then study the kidneys
and control of body fluid volume in a different chapter. In the a1cq.2u iFruen icst itohne a nadb Milietcyh atoni stmhink critically and use informa- It is my hope that by reading this book, you will
functioning human, however, the cardiovascular and renal systems
communicate with each other, so that a change in one is likely to tiWoen de ftinoe p hsyosiollovgey a sp threo nobrmleal mfuncsti.o nAings o fy toheu bo dsyt, buutd y physiology, you de velop an integrated view of physiology that allows
cause a reaction in the other. For example, body fluid volume influ- physiologists are careful to distinguish between function and mecha-
ences blood pressure, while changes in blood pressure alter kidney shnisom.u Thled fu bncetio np orf ea pphyasiorloegidca l styoste mp orr aevecntt iisc thee “wthhy”e se skills. You will find you to enter your chosen profession with respect for
function because the kidneys regulate fluid volume. In this book, of the system or event: Why does a certain response help an animal
you will find several integrative physiology chapters that highlight as unrvuivem in ab peartric uolarf s itfueatiaont? uIn rotehesr wionrd st, whhaits i s btheo adoapktive, such as the Concept the complexity of the human body and a clear vision of
the coordination of function across multiple organ systems. significance of this event for this animal?
Understanding how different organ systems work together is CheFcork e xqamuplee, shutmioanns asre alanrged, m Fobiigle, uterrreest raialn andim aGls, raph Questions. These the potential of physiological and biomedical research.
just as important as memorizing facts, but the complexity of inter- and our bodies maintain relatively constant water content despite
actions can be challenging. One way physiologists simplify and ”ltiveinsg tin ay doryu, hirgshley vlafr”iab lqe euxteernsatl einovinronsm aenrt. eDe hdyderastiiogn ned to challenge May you find physiology as fun and exciting I do. Good
integrate information is by using visual representations of physi- is a constant threat to our well-being. What processes have evolved
ological processes called maps. The Focus on Mapping feature in yoin uourr a ncartoimtyi canad lp htyhsioilongyk thiant agllo wa uns tod su arvinvea inl tyhiss hioss -skills. In each chapter, luck with your studies!
this chapter will help you learn how to make maps. The first type tile environment? One is the production of highly concentrated
of map, shown in FIGURE 1.3A, is a schematic representation of reurainde b yt thhe ekid nReyu, wnhicnh ianllogws tPher boodby tloe comnse rvae sw aytero. Tuhi s work through the Warmest regards,
s1t.r3ubc,t duiraeg orar mfusn ac ptihoyns.i oTlohgei csaelc opnrodc etyssp ae so itf pmroacpe,e sdhso twhrno uing hF itgimuree. testetaxllt eutms heaonwtn ttehdlels kusisd ewneheyy wa ciecf po rmoypdoluischuee cs o tcnhcaaet nntatrsa kta.edp urpinley bu tw dohes anott you’re reading to Dr. Dee (as my students call me)
the clinical scenario described in the problem. [email protected]
M01_SILV5197_08_SE_C01.indd 4 Phys in Action Video Topic9/s11/:17 11:49 AM Try It Activities:
pp. 164–165 Fig. 5.4 Osmolarity & Tonicity p. 57 Graphing
pp. 190–191 Fig. 5.23 Membrane Potential p. 171 Membrane Models (Lipid bylayer)
pp. 492–493 Fig.14.16 Electrocardiogram p. 287 Action Potential
p. 529 Fig. 15.14 Cardiovascular Control p. 361 Salty-Sweet Taste Experiment
p. 579 Fig. 17.7a The Spirometer p. 504 Frank-Starling Law of the Heart
p. 583 Fig. 17.10 Respiratory Pressure p. 641 Insulin
p. 590 Fig. 17.13 Alveolar Gases p. 718 Oral Rehydration Therapy
p. 607 Fig. 18.7 Hemoglobin-Oxygen Transport
p. 646 Fig. 19.14 Renal Clearance
p. 829 Fig. 25.8 Blood Pressure & Exercise
A01_SILV9543_08_GE_FM.indd 3 09/07/2018 13:53
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A01_SILV9543_08_GE_FM.indd 4 09/07/2018 13:53
Move Beyond Memorization:
Prepare for Tomorrow’s Challenges
The goals for the Eighth Global Edition of Human Physiology: An Integrated Approach are to provide
an integrated and up-to-date introduction to core concepts in physiology and to equip you with skills
for solving real-world problems.
Harlow, England • London • New York • Boston • San Francisco • Toronto • Sydney
Dubai • Singapore • Hong Kong • Tokyo • Seoul • Taipei • New Delhi
Cape Town • São Paulo • Mexico City • Madrid • Amsterdam • Munich • Paris • Milan
A01_SILV9543_08_GE_FM.indd 5 09/07/2018 13:53
120 CHAPTER 3 Compartmentation: Cells and Tissues
TABLE 3.4 Characteristics of the Four Tissue Types
Epithelial Connective Muscle Nerve
Matrix Amount Minimal Extensive Minimal Minimal
Matrix Type Basal lamina Varied—protein fibers External lamina External lamina
in ground substance
that ranges from liquid
to gelatinous to firm to
calcified
Unique Features No direct blood supply Cartilage has no blood Able to generate electri- Able to generate
supply cal signals, force, and electrical signals
movement
Surface Features of Cells Microvilli, cilia N/A N/A N/A
Locations Covers body surface; Supports skin and other Makes up skeletal Throughout body;
lines cavities and hollow organs; cartilage, bone, muscles, hollow organs, concentrated in brain
organs, and tubes; secre- and blood and tubes and spinal cord
tory glands
Cell Arrangement Variable number of layers, Cells not in layers; usu- Cells linked in sheets or Cells isolated or net-
and Shapes from one to many; cells ally randomly scattered elongated bundles; cells worked; cell append-
flattened, cuboidal, or in matrix; cell shape shaped in elongated, ages highly branched
columnar irregular to round thin cylinders; heart and/or elongated
muscle cells may be
branched
Challenge Yourself:
3.5 Tissue Remodeling deteriorate, and finally the cells rupture. The cell contents released
Apply What You Learn this way include digestive enzymes that damage adjacent cells and
Most people associate growth with the period from birth to adult- trigger an inflammatory response. You see necrosis when you have
hood. However, cell birth, growth, and death continue throughout a red area of skin surrounding a scab.
a person’s life. The tissues of the body are constantly remodeled as In contrast, cells that undergo programmed cell death, or apoptosis
cells die and are replaced. {ap-oh-TOE-sis or a-pop-TOE-sis; apo-, apart, away + ptosis,
falling}, do not disrupt their neighbors when they die. Apoptosis,
Learning physiology requires that you use information rather Athpaonp tsoismisp lIys ma eTmidoyr Fizoinrmg wofh Caet lyl oDue tahthink will be on also called cell suicide, is a complex process regulated by multiple
the test. The Eighth Edition text and Mastering™ A&P program provide multiple opportunities for you to practice chemical signals. Some signals keep apoptosis from occurring,
Cell death occurs two ways, one messy and one tidy. In necrosis,
answering the more challenging types of questions that you are likely to see on a test or exam. while other signals tell the cell to self-destruct. When the suicide
cells die from physical trauma, toxins, or lack of oxygen when
signal wins out, chromatin in the nucleus condenses, and the cell
their blood supply is cut off. Necrotic cells swell, their organelles
pulls away from its neighbors. It shrinks, then breaks up into tidy
membrane-bound blebs that are gobbled up by neighboring cells or
Running Problems explore a real-world disease or disorder by wandering cells of the immune system.
that unfolds in short segments throughout the chapter. You Apoptosis is a normal event in the life of an organism. During
can check your understanding by comparing your answers RUNNING PROBLEM fetal development, apoptosis removes unneeded cells, such as half
with those in Problem Conclusion at the end of each chapter. The day after Jan’s visit, the computerized cytology analysis sys- the cells in the developing brain and the webs of skin between fin-
Related Coaching Activities can be assigned in Mastering A&P. tem rapidly scans the cells on the slide of Jan’s cervical tissue, gers and toes. In adults, cells that are subject to wear and tear from
looking for abnormal cell size or shape. The computer is pro- exposure to the outside environment may live only a day or two
grammed to find multiple views for the cytologist to evaluate. The before undergoing apoptosis. For example, it has been estimated
results of Jan’s two Pap tests are shown in FIGURE 3.14. that the intestinal epithelium is completely replaced with new cells
every two to five days.
Q6: Has Jan’s dysplasia improved or worsened? What
evidence do you have to support your answer?
Q7: Use your answer to question 6 to predict whether Jan’s
HPV infection has persisted or been cleared by her immune Concept Check
system.
29. What are some features of apoptosis that distinguish it from
cell death due to injury?
95 97 101 115 120 123
see pp. 120–121
7.6 Hormone Evolution 217
FIG. 7.15 Hypocortisolism profession. Now, with genetic engineering, the human gene for
insulin has been inserted into bacteria, which then synthesize
(a) Hyposecretion from (b) Hyposecretion from Atrophy the hormone, providing us with a plentiful source of human
M03_SILV9543_0D8a_mGEa_gCe0 t3o.i ntdhde P 1i2t0uitary of the Adrenal Cortex insulin. 6/9/18 4:46 PM
Although many hormones have the same function in most
vertebrates, a few hormones that play a significant role in the
Hypothalamus CRH Hypothalamus CRH
physiology of lower vertebrates seem to be evolutionarily “on
their way out” in humans. Calcitonin is a good example of
such a hormone. It plays a role in calcium metabolism in fish CH
but apparently has no significant influence on daily calcium AP
Anterior pituitary ACTH Anterior pituitary ACTH T
balance in adult humans. Neither calcitonin deficiency nor cal- E
Additional Practice Questions include Concept Check R
citonin excess is associated with any pathological condition or
Questions, which are placed at intervals throughout the symptom. 7
chapter, and Review Questions, which are provided at the end Although calcitonin is not a significant hormone in humans,
of the chapter and organized into four levels of difficulty. An Adrenal cortex Cortisol Adrenal cortex Cortisol the calcitonin gene does code for a biologically active protein. In
answer key is in Appendix A. the brain, cells process mRNA from the calcitonin gene to make
a peptide known as calcitonin gene-related peptide (CGRP), which acts
as a neurotransmitter. The ability of one gene to produce multiple
Symptoms Symptoms
peptides is one reason research is shifting from genomics to physiol-
of of
deficiency deficiency ogy and proteomics (the study of the role of proteins in physiological
function).
Some endocrine structures that are important in lower ver-
tebrates are vestigial {vestigium, trace} in humans, meaning that
FIGURE QUESTION
in humans these structures are present as minimally functional
For each condition, use arrows to indicate whether
glands. For example, melanocyte-stimulating hormone (MSH) from the
levels of the three hormones in the pathway will be
increased, decreased, or unchanged. Draw in intermediate lobe of the pituitary controls pigmentation in rep-
Figure Questions challenge you to apply visual literacy negative feedback loops where functional. tiles and amphibians. However, adult humans have only a vestigial
skills as you read an illustration or photo. Answers to these intermediate lobe and normally do not have measurable levels of
questions appear at the end of the text, in Appendix A. See p. 253 MSH in their blood.
In the research arena, comparative endocrinology—the study
7.6 Hormone Evolution of endocrinology in nonhuman organisms—has made signifi-
cant contributions to our quest to understand the human body.
Chemical signaling is an ancient method for communication
Many of our models of human physiology are based on research
and the maintenance of homeostasis. As scientists sequence
the genomes of diverse species, they are discovering that in
many cases hormone structure and function have changed
amazingly little from the most primitive vertebrates through
RUNNING PROBLEM
the mammals. In fact, hormone signaling pathways that were
A01_SILV9543_08_GE_FM.indd 6 once considered exclusive to vertebrates, such as those for Resea09rc/0h7e/r2s0 1h8a v e1 3le:5a3rned that Graves’ disease is an autoimmune
thyroid hormones and insulin, have now been shown to play disorder in which the body fails to recognize its own tissue. In
physiological or developmental roles in invertebrates such this condition, the body produces antibodies that mimic TSH and
bind to the TSH receptor, turning it on. This false signal “fools” the
as echinoderms and insects. This evolutionary conservation of
thyroid gland into overproducing thyroid hormone. More women
hormone function is also demonstrated by the fact that some
than men are diagnosed with Graves’ disease, perhaps because
hormones from other organisms have biological activity when
of the influence of female hormones on thyroid function. Stress
administered to humans. By studying which portions of a hor-
and other environmental factors have also been implicated in
mone molecule do not change from species to species, scientists
hyperthyroidism.
have acquired important clues to aid in the design of agonist
and antagonist drugs. Q7: Antibodies are proteins that bind to the TSH receptor. From
The ability of nonhuman hormones to work in humans was that information, what can you conclude about the cellular loca-
tion of the TSH receptor?
a critical factor in the birth of endocrinology. When Best and
Banting discovered insulin in 1921 and the first diabetic patients Q8: In Graves’ disease, why doesn’t negative feedback shut off
were treated with the hormone, the insulin was extracted from thyroid hormone production before it becomes excessive?
cow, pig, or sheep pancreases. Before the mid-1980s, slaugh-
195 204 212 214 216 217 219
terhouses were the major source of insulin for the medical
M07_SILV5197_08_SE_C07.indd 217 10/3/17 12:50 PM
Practice Solving
Real-World Problems
NEW! Additional questions for each “Try it”
activity are available in Mastering A&P. Topics include
Graphing (Chapter 1), Cell Membranes (Chapter 5), Action
Potentials (Chapter 8), Salty-Sweet Taste Experiment
NEW! “Try it” boxes present a real-world research
(Chapter 10), Frank-Starling Law of the Heart (Chapter 14),
problem or classic experiment and guide you through
Insulin (Chapter 19) and Oral Rehydration Therapy
the process of analyzing the data and thinking like a
(Chapter 21).
scientist.
See p. 287
Graph Questions encourage you
to interpret real data presented in graphs.
Answers to these questions appear at the end
of the text, in Appendix A.
A01_SILV9543_08_GE_FM.indd 7 09/07/2018 13:53
Study More Efficiently
Using the Figures
Eye-tracking research has shown that learning and comprehension levels are higher for students who study both
the figures and the text together than for students who only read the text. This book offers dozens of illustrations
designed to help you learn physiology more efficiently, and make the best use of your study time.
Essentials Figures distill the basics of a topic into one or two pages, helping
Selected figures from the text are
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FIG. 5.23 ESSENTIALS Membrane Potential @Mastering Anatomy & Physiology
The electrical disequilibrium that exists
between the extracellular fluid (ECF) and (a) In illustrations, this uneven distribution of Electrochemical Equilibrium
charge is often shown by the charge symbols
intracellular fluid (ICF) of living cells is called clustered on each side of the cell membrane. For any given concentration gradient [Ion]out – [Ion]in (e) In this example, the concentration gradient sending K+
the membrane potential difference (Vm), or across a cell membrane, there is a membrane out of the cell is exactly opposed by the electrical gradient
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Creation of a Membrane Potential in an Artificial System
To show how a membrane potential difference can arise from ion concentration gradients
and a selectively permeable membrane, we will use an artificial cell system where we can
control the membrane’s permeability to ions and the composition of the ECF and ICF. Equilibrium Potential
(EbC) FW (hceonm wpoes beedg oinf ,N thae+ caenldl hCals– nioon sm) eamndb rtahnee I CpFo t(eKn+ti aaln: dT he + – + – KEY Fgoivre ann cyo inocne, nthtrea tmioenm gbraradnieen pt oist eknntoiawl tnh aast ethxaec etlqyu oilpibproiusmes a Approximate Values for Mammalian Cells
large anions, A– ) areTcmm oheeonelmve cescebymtnrrsaitectrnenaaemtltl i yooa infcsn t ieogisnu nr aatcsrsda h bilaee.enmnt wtiisnce safeoul nrlda aittshollee rfq otIuoCui lrFpi bi roareinnuvsdem. n E,Tt C whfreFiet. hec ell +– –+ +––+–+ +––+ ++– ++–– SCPLohaodlrtogaiuresimd saei uni oimioonnn ion cpoontecnetnEitariola n(tEi o=ionn 6)gz. 1rTaoldo cgiean[lic[toi,ou nwlna]oe]tienu u ttshee tehwoqenhu eNtihrlieeeb r rznioi usinsmt. te(h ipq.eeou .c,ta ehKtnaio+rt ngi=ae: l + fo1)r any Using NthCKael++–se valueI111Cs550 F0for K+ and the115E 40NC58eFrnst equation, the EK is ]90 mV.
– The Nernst equation is used for a cell that is freely permeable
+ + – to only one ion at a time. Living cells, however, have limited
– permeability to several ions. To calculate the actual membrane FIGURE QUESTIONS(You will need the log function on a calculator.)
potential of cells, we use a multi-ion equation called the 3. Calculate the equilibrium potential for Na+ (ENa).
Goldman-Hodgkin-Katz equation [discussed in Chapter 8]. 4. Calculate the ECl.
(mce) mNobwra nwee, minsaekrint ga tlehaek c cehll afnreneelyl fpoer rKm+e ianbtole t htoe K+. + – + – 1 We insert a leak channel for K+.
+
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+ +
–
(cmdoo)n rAcese n naetdrgadatititoiivonen gaarln aKdd+ ite hinoetn ,o stu hletesa iidvnees itdbheee c ocofe mtlhle,e sg comeinollg rbe de pocowosmnit eitvhsee .ir + – + – + + 4 Additional K+ leaves the cell. + – + –
– + – + + Intracellular fluid Extracellular fluid
+ On a number line, the ECF would be at +1
How much K+ will leave the cell? – – – 5 Now the negative charge and the ICF at −1. Absolute charge scale
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See p. 190
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A01_SILV9543_08_GE_FM.indd 8 09/07/2018 13:53