World Book's Learning LaddersBodyWORLDBOOKwww.worldbook.comWorld Book,Inc.180 North LaSalle StreetSuite 900USAFor information about other World Book publications,visit our website at www.worldbook.com or call1-800W0 RLDBK(967.5325).For information about sales to schools and libraries,call 1-800-975-3250 (United States):1-800-837-5365(Canada).2008 revised printing2008 World Book,Inc.All rights reserved.This book may not be reproduced in whole or in part inany form without prior written permission from the publisher.WORLD BOOK and the GLOBE DEVICE are registered trademarks or trademarks of World Book,Inc.Library of Congress Cataloging-in-Publication DataStaffExecutive CommitteeMy body.President:Jim O'Rourkep.cm.-(World Book's leaming ladders)Vice President and Editor in Chief:Paul A.KobasaSummary:"Introduction to the human body andVice President,Finance:Donald D.Kellerhow it works using simple text,question and answerVice President,Marketing:Jean Linformat,illustrations,and photos.Features includeVice President,International Sales:Maksim Rutenbergpuzzles and games,fun facts,a resource list,andDirector,Human Resources:Bev Eckeran index"--Provided by publisher.Editorial1SBN978-0-7166-7727-7Director,Digital Print Content Development:Emily Kline1.Body,Human--Juvenile literature.2.HumanEditor,Digital Print Content Development:Kendra Muntzphysiology--Juvenile literature.I.World Book,Inc.Senior Editor:Shawn BrennanOP37.M92008Senior Editor:Dawn Krajcik612.-dc22Manager,Indexing Services:David Pofelski2007018908Manager,Contracts Compliance (Rights Permissions):Loranne K.ShieldsWorld Book's Leaming LaddersDigitalISBN978-0-7166-7725-3(set,hc)Director,Digital Product Development:Erika MellerDigital Product Manager:Jonathan WillsAlso available as:ISBN 978-0-7166-7752-9 (e-book,Learning Hub)Graphics and DesignISBN 978-0-7166-7753-6(e-book,Spindle)Senior Art Director:Tom EvansISBN978-0-7166-7754-3(e-book,EPUB3)Coordinator,Design Development and Production:Brenda B.Tropinski1SBN978-0-7166-7755-0(e-book,PDF)Manufacturing/Pre-PressPrinted in China by Shenzhen Wing King TongManufacturing Manager:Anne FritzingerPaper Products Co,Ltd.,Shenzhen,GuangdongProofreader:Nathalie StrassheimI Ith printing May 2017This edition is an adaptationof the Lodders series publishedPhotographic credits:Cover:BestPhotoStudio/Shutterstock;p4:originally by T&N Children'sJohnny Greig.Alamy Imoges;p6:Lori Adamski Peek,Getty Imoges;Publishing,Inc.,ofMinnetonka,MinnesotaAlamy Images;p16:Barry Rosenthal,Getty Images;p17:DavidR.Frazier Photolibrary/Alamy Imoges;p19:David Hancock,AlamyAlamy Images;p22:Christina Kennedy,Getty Images;p23:ChuckIllustrators:Rhian Nest James,Jon Stuort