Marieb Human
Anatomy &
Physiology
Katja Hoehn
Lawrence W. Haynes
Matthew A. Abbott
T WEL FTH E D I TI O N
,Marieb Human
Anatomy
& Physiology
TWELFTH EDITION
Katja Hoehn, M.D., Ph.D.
Mount Royal University
Lawrence W. Haynes, Ph.D.
Matthew A. Abbott, Ph.D.
Des Moines Area Community College
,Content Development: Matthew Walker, Mary Ann Murray, Hilair Chism Product Marketing: Tim Galligan, Courtney Davis, Yez Alayan, Ben Piercy
Product and Content Management: Michael Gillespie, Serina Beauparlant, Rights and Permissions: Ben Ferrini, Matthew Perry, Chenley Calites-Bulagao
Ayushi Khandelwal
Content Production: Katie Foley, Shercian Kinosian, Mary Tindle, Straive, Jan
Troutt, Troutt Visual Services, LLC, Tod Regan, Lauren Hill, Lauren Chen,
Mathew Koul, Nishant Bhaskar, Kristen Antal, Micah Brenner, Jerilyn DiCarlo
Please contact www.AskPearsonSupport.com with any queries on this content.
Please contact us with concerns about any potential bias at https://www.pearson.com/report-bias.html
You can learn more about Pearson’s commitment to accessibility at https://www.pearson.com/us/accessibility.html
Cover Image by David Ramos/Getty Images Sport / Getty Images
Microsoft and/or its respective suppliers make no representations about the suitability of the information
contained in the documents and related graphics published as part of the services for any purpose. All such
documents and related graphics are provided “as is” without warranty of any kind. Microsoft and/or its
respective suppliers hereby disclaim all warranties and conditions with regard to this information, including
all warranties and conditions of merchantability, whether express, implied or statutory, fitness for a particular
purpose, title and non-infringement. In no event shall Microsoft and/or its respective suppliers be liable for any
special, indirect or consequential damages or any damages whatsoever resulting from loss of use, data or profits,
whether in an action of contract, negligence or other tortious action, arising out of or in connection with the use
or performance of information available from the services.
The documents and related graphics contained herein could include technical inaccuracies or typographical
errors. Changes are periodically added to the information herein. Microsoft and/or its respective suppliers may
make improvements and/or changes in the product(s) and/or the program(s) described herein at any time. Partial
screen shots may be viewed in full within the software version specified.
Microsoft® and Windows® are registered trademarks of the Microsoft Corporation in the U.S.A. and other
countries. This book is not sponsored or endorsed by or affiliated with the Microsoft Corporation.
Copyright © 2025, 2019, 2016 by Pearson Education, Inc., or its affiliates, 221 River Street, Hoboken, NJ 07030.
All Rights Reserved. Manufactured in the United States of America. This publication is protected by copyright,
and permission should be obtained from the publisher prior to any prohibited reproduction, storage in a retrieval
system, or transmission in any form or by any means, electronic, mechanical, photocopying, recording, or
otherwise. For information regarding permissions, request forms, and the appropriate contacts within the Pearson
Education Global Rights and Permissions department, please visit www.pearsoned.com/permissions/.
Acknowledgments of third-party content appear on the appropriate page within the text or on C-1.
PEARSON, Mastering® A&P, Practice Anatomy Lab™, PAL™, Interactive Physiology®, and A&P Flix® are
exclusive trademarks owned by Pearson Education, Inc., or its affiliates in the U.S. and/or other countries.
Unless otherwise indicated herein, any third-party trademarks, logos, or icons that may appear in this work
are the property of their respective owners, and any references to third-party trademarks, logos, icons, or other
trade dress are for demonstrative or descriptive purposes only. Such references are not intended to imply any
sponsorship, endorsement, authorization, or promotion of Pearson’s products by the owners of such marks, or any
relationship between the owner and Pearson Education, Inc., or its affiliates, authors, licensees, or distributors.
Jell-O® is a registered trademark of Kraft Foods Global Brands LLC. Ozempic® is a registered trademark of NovoNordiskA/S
Slinky® is a registered trademark of Poof-Slinky Inc. Wegovy® is a registered trademark of NovoNordiskA/S
Ziploc® is a registered trademark of S. C. Johnson & Son, Inc. Phexxi® is a registered trademark of Evofem Biosciences, Inc.
Velcro® is a registered trademark of Velcro IP Holdings LLC. Nexplanon® is a registered trademark of MSD Oss B.V.
Zokinvy® is a registered trademark of Eiger BioPharmaceuticals, Inc. Depo-Provera® is a registered trademark of Pharmacia & Upjohn Company LLC.
Viagra® is a registered trademark of Upjohn US 1 LLC. PowerPoint® is a registered trademark of Microsoft Corporation.
Ventolin® is a registered trademark of Glaxo Group Limited. Microsoft® is a registered trademark of Microsoft Corporation.
Drāno® is a registered trademark of S. C. Johnson & Son, Inc. TestGen® is a registered trademark of Tamarack Software Inc.
Lego® is a registered trademark of Lego Juris A/S.
Library of Congress Cataloging-in-Publication Data
Cataloging-in-Publication Data is available on file at the Library of Congress.
$PrintCode
ISBN-10: 0138242739
ISBN-13: 9780138242732
, We dedicate this work to our students both
About the Authors present and past, who always inspire us to
“push the envelope.”
The author team’s contributions reflect their expertise as biolo-
gists and medical researchers and their teaching sensibilities
gained from years of experience at diverse institutions. Katja
Hoehn was handpicked by Elaine Marieb back in 2002 to become
her coauthor starting with the 7th edition of the textbook.
Elaine N. Marieb Lawrence W. Haynes
Elaine N. Marieb (1936–2018) received Lawrence W. Haynes was awarded both
her Ph.D. in zoology from the University of his bachelor’s (in biological sciences, 1980)
Massachusetts at Amherst. Shortly after she and Ph.D. (in physiology, 1984) degrees by
joined the faculty of the biology department at the University of California, Davis. After
Holyoke Community College, Elaine famously enrolled in a nursing research stints at the University of Texas Medical Branch in
degree program while she was teaching anatomy and physiology to Galveston and the Howard Hughes Medical Institute at Johns
aspiring nursing students. This unique experience gave Elaine spe- Hopkins School of Medicine, he joined the Department of
cial insights into the foundational knowledge that nurses needed to Physiology at the University of Calgary Medical School in
master. Armed with this insight and a clear talent for teaching and 1989, where he enjoyed teaching medical students and gradu-
writing, Elaine authored Human Anatomy & Physiology, which ate students. His main area of interest has always been photo-
became an immediate hit with instructors and students. transduction, and he has published a number of papers on the
A critical part of Elaine’s legacy is The Elaine Nicpon cGMP-gated channels of photoreceptors. He has been involved
Marieb Charitable Foundation. The foundation has helped with this book (behind the scenes) for as long as his partner,
fund numerous science and nursing programs and scholarships Katja, and has authored or revised many Interactive Physiol-
at the College of Nursing at the University of Massachusetts, ogy modules and figure animations. Together, Larry and Katja
Florida Gulf Coast University, Holyoke Community College, provide financial support for students in the form of the Hoehn-
and Mount Holyoke College as well as sponsoring the Human Haynes scholarship that they established in 2006 for nursing
Anatomy & Physiology Society (HAPS) Marieb, Hoehn, students at Mount Royal University. Larry likes to ski and hike
Haynes, & Abbott Award for Diversity, Equity, and Inclusion. with Katja . . . but draws the line at triathlons.
Katja Hoehn Matthew A. Abbott
Katja Hoehn is a professor emerita in the Matthew A. Abbott earned his bachelor’s
Department of Biology at Mount Royal degree in biology at Grinnell College and his
University in Calgary, Canada. Katja’s first Ph.D. in genetics at Iowa State University.
love is teaching. Her teaching excellence In 2007, he joined the faculty at Des Moines
has been recognized by several awards during her 30 years Area Community College, where he is passionately devoted to
at Mount Royal University. Katja received her M.D. (with helping students learn anatomy and physiology as they prepare for
Distinction) from the University of Saskatchewan, and her Ph.D. a career in nursing or other allied health fields. For many years,
in pharmacology from Dalhousie University. She has written he has contributed to ancillary materials for this textbook as a
numerous research papers in neuroscience and pharmacology, reviewer and author. Dr. Abbott is a member of the Human Anat-
and received a Dalhousie Medical Research Foundation Award omy and Physiology Society (HAPS) and the Iowa Association
for excellence in medical research, and a Career Achievement of Community College Biology Teachers (IACCBT). In addition
Award from Mount Royal University. Katja likes to spend time to his love for teaching, he enjoys biking and has participated in
outdoors hiking, skiing, and competing in long-course triath- RAGBRAI, an annual bicycle ride across his home state of Iowa,
lons. She also plays Irish flute down at the local pub. over 25 times.
iii
Anatomy &
Physiology
Katja Hoehn
Lawrence W. Haynes
Matthew A. Abbott
T WEL FTH E D I TI O N
,Marieb Human
Anatomy
& Physiology
TWELFTH EDITION
Katja Hoehn, M.D., Ph.D.
Mount Royal University
Lawrence W. Haynes, Ph.D.
Matthew A. Abbott, Ph.D.
Des Moines Area Community College
,Content Development: Matthew Walker, Mary Ann Murray, Hilair Chism Product Marketing: Tim Galligan, Courtney Davis, Yez Alayan, Ben Piercy
Product and Content Management: Michael Gillespie, Serina Beauparlant, Rights and Permissions: Ben Ferrini, Matthew Perry, Chenley Calites-Bulagao
Ayushi Khandelwal
Content Production: Katie Foley, Shercian Kinosian, Mary Tindle, Straive, Jan
Troutt, Troutt Visual Services, LLC, Tod Regan, Lauren Hill, Lauren Chen,
Mathew Koul, Nishant Bhaskar, Kristen Antal, Micah Brenner, Jerilyn DiCarlo
Please contact www.AskPearsonSupport.com with any queries on this content.
Please contact us with concerns about any potential bias at https://www.pearson.com/report-bias.html
You can learn more about Pearson’s commitment to accessibility at https://www.pearson.com/us/accessibility.html
Cover Image by David Ramos/Getty Images Sport / Getty Images
Microsoft and/or its respective suppliers make no representations about the suitability of the information
contained in the documents and related graphics published as part of the services for any purpose. All such
documents and related graphics are provided “as is” without warranty of any kind. Microsoft and/or its
respective suppliers hereby disclaim all warranties and conditions with regard to this information, including
all warranties and conditions of merchantability, whether express, implied or statutory, fitness for a particular
purpose, title and non-infringement. In no event shall Microsoft and/or its respective suppliers be liable for any
special, indirect or consequential damages or any damages whatsoever resulting from loss of use, data or profits,
whether in an action of contract, negligence or other tortious action, arising out of or in connection with the use
or performance of information available from the services.
The documents and related graphics contained herein could include technical inaccuracies or typographical
errors. Changes are periodically added to the information herein. Microsoft and/or its respective suppliers may
make improvements and/or changes in the product(s) and/or the program(s) described herein at any time. Partial
screen shots may be viewed in full within the software version specified.
Microsoft® and Windows® are registered trademarks of the Microsoft Corporation in the U.S.A. and other
countries. This book is not sponsored or endorsed by or affiliated with the Microsoft Corporation.
Copyright © 2025, 2019, 2016 by Pearson Education, Inc., or its affiliates, 221 River Street, Hoboken, NJ 07030.
All Rights Reserved. Manufactured in the United States of America. This publication is protected by copyright,
and permission should be obtained from the publisher prior to any prohibited reproduction, storage in a retrieval
system, or transmission in any form or by any means, electronic, mechanical, photocopying, recording, or
otherwise. For information regarding permissions, request forms, and the appropriate contacts within the Pearson
Education Global Rights and Permissions department, please visit www.pearsoned.com/permissions/.
Acknowledgments of third-party content appear on the appropriate page within the text or on C-1.
PEARSON, Mastering® A&P, Practice Anatomy Lab™, PAL™, Interactive Physiology®, and A&P Flix® are
exclusive trademarks owned by Pearson Education, Inc., or its affiliates in the U.S. and/or other countries.
Unless otherwise indicated herein, any third-party trademarks, logos, or icons that may appear in this work
are the property of their respective owners, and any references to third-party trademarks, logos, icons, or other
trade dress are for demonstrative or descriptive purposes only. Such references are not intended to imply any
sponsorship, endorsement, authorization, or promotion of Pearson’s products by the owners of such marks, or any
relationship between the owner and Pearson Education, Inc., or its affiliates, authors, licensees, or distributors.
Jell-O® is a registered trademark of Kraft Foods Global Brands LLC. Ozempic® is a registered trademark of NovoNordiskA/S
Slinky® is a registered trademark of Poof-Slinky Inc. Wegovy® is a registered trademark of NovoNordiskA/S
Ziploc® is a registered trademark of S. C. Johnson & Son, Inc. Phexxi® is a registered trademark of Evofem Biosciences, Inc.
Velcro® is a registered trademark of Velcro IP Holdings LLC. Nexplanon® is a registered trademark of MSD Oss B.V.
Zokinvy® is a registered trademark of Eiger BioPharmaceuticals, Inc. Depo-Provera® is a registered trademark of Pharmacia & Upjohn Company LLC.
Viagra® is a registered trademark of Upjohn US 1 LLC. PowerPoint® is a registered trademark of Microsoft Corporation.
Ventolin® is a registered trademark of Glaxo Group Limited. Microsoft® is a registered trademark of Microsoft Corporation.
Drāno® is a registered trademark of S. C. Johnson & Son, Inc. TestGen® is a registered trademark of Tamarack Software Inc.
Lego® is a registered trademark of Lego Juris A/S.
Library of Congress Cataloging-in-Publication Data
Cataloging-in-Publication Data is available on file at the Library of Congress.
$PrintCode
ISBN-10: 0138242739
ISBN-13: 9780138242732
, We dedicate this work to our students both
About the Authors present and past, who always inspire us to
“push the envelope.”
The author team’s contributions reflect their expertise as biolo-
gists and medical researchers and their teaching sensibilities
gained from years of experience at diverse institutions. Katja
Hoehn was handpicked by Elaine Marieb back in 2002 to become
her coauthor starting with the 7th edition of the textbook.
Elaine N. Marieb Lawrence W. Haynes
Elaine N. Marieb (1936–2018) received Lawrence W. Haynes was awarded both
her Ph.D. in zoology from the University of his bachelor’s (in biological sciences, 1980)
Massachusetts at Amherst. Shortly after she and Ph.D. (in physiology, 1984) degrees by
joined the faculty of the biology department at the University of California, Davis. After
Holyoke Community College, Elaine famously enrolled in a nursing research stints at the University of Texas Medical Branch in
degree program while she was teaching anatomy and physiology to Galveston and the Howard Hughes Medical Institute at Johns
aspiring nursing students. This unique experience gave Elaine spe- Hopkins School of Medicine, he joined the Department of
cial insights into the foundational knowledge that nurses needed to Physiology at the University of Calgary Medical School in
master. Armed with this insight and a clear talent for teaching and 1989, where he enjoyed teaching medical students and gradu-
writing, Elaine authored Human Anatomy & Physiology, which ate students. His main area of interest has always been photo-
became an immediate hit with instructors and students. transduction, and he has published a number of papers on the
A critical part of Elaine’s legacy is The Elaine Nicpon cGMP-gated channels of photoreceptors. He has been involved
Marieb Charitable Foundation. The foundation has helped with this book (behind the scenes) for as long as his partner,
fund numerous science and nursing programs and scholarships Katja, and has authored or revised many Interactive Physiol-
at the College of Nursing at the University of Massachusetts, ogy modules and figure animations. Together, Larry and Katja
Florida Gulf Coast University, Holyoke Community College, provide financial support for students in the form of the Hoehn-
and Mount Holyoke College as well as sponsoring the Human Haynes scholarship that they established in 2006 for nursing
Anatomy & Physiology Society (HAPS) Marieb, Hoehn, students at Mount Royal University. Larry likes to ski and hike
Haynes, & Abbott Award for Diversity, Equity, and Inclusion. with Katja . . . but draws the line at triathlons.
Katja Hoehn Matthew A. Abbott
Katja Hoehn is a professor emerita in the Matthew A. Abbott earned his bachelor’s
Department of Biology at Mount Royal degree in biology at Grinnell College and his
University in Calgary, Canada. Katja’s first Ph.D. in genetics at Iowa State University.
love is teaching. Her teaching excellence In 2007, he joined the faculty at Des Moines
has been recognized by several awards during her 30 years Area Community College, where he is passionately devoted to
at Mount Royal University. Katja received her M.D. (with helping students learn anatomy and physiology as they prepare for
Distinction) from the University of Saskatchewan, and her Ph.D. a career in nursing or other allied health fields. For many years,
in pharmacology from Dalhousie University. She has written he has contributed to ancillary materials for this textbook as a
numerous research papers in neuroscience and pharmacology, reviewer and author. Dr. Abbott is a member of the Human Anat-
and received a Dalhousie Medical Research Foundation Award omy and Physiology Society (HAPS) and the Iowa Association
for excellence in medical research, and a Career Achievement of Community College Biology Teachers (IACCBT). In addition
Award from Mount Royal University. Katja likes to spend time to his love for teaching, he enjoys biking and has participated in
outdoors hiking, skiing, and competing in long-course triath- RAGBRAI, an annual bicycle ride across his home state of Iowa,
lons. She also plays Irish flute down at the local pub. over 25 times.
iii
