W USBORNE THEUSBORNE COMPLETE BOOKOFTHE Internet linked l H l . : I O ) l O O H l l l 1 d W O ~3 : N ' H O H S n 3 : H ! UsingInternetlinks Thisbook containsdescriptions of websiteswhere youcanfind out moreabout thehumanbody. Tovisit them,go to theUsborne QuicklinksWebsiteat www.usborne-quicklinks.comand enter thekeywords"completebody." What youneed Most of thewebsiteslistedinthisbook can beaccessedusinga standardhome computer anda browser (the softwarethat letsyoulook atinformationonthe Internet). Somesitesneedextraprograms, knownasplug-ins,to play soundor show videos.If yougotoa siteanddonot have theright plug-in,a messagewillcomeup onthe screen. Thereisusuallya buttonon thesitethat youcanclickonto download theplug-in.Alternatively,go toUsborneQuickl inks andclickonNet Help to findlinksto downloadplug-ins. This microscopepicture showsa tinyembryomade upof just a few cellson t he point of a needl e. Overnine months,it willgrowinto a fully formedhumanbeing. Siteavailability ThelinksinUsborneQuicklinksareregularly updated,but sitesmay sometimesbe temporarilyunavailable.If a websitecloses downcompletely,wewill,if possible, replaceit withanalternative.Youwillfind anup-to-datelistof sitesontheUsborne QuicklinksWebsite. Downloadablepictures Someof thepicturesinthisbook canbe downloaded fromtheUsborneQuicklinks Websiteandprintedout for your own personaluse- for example,asillustrations forhomework. Theymust not,however,be copiedor distributedfor anycommercial purpose. Downloadablepictureshavea * symbolbesidethem.Toprint out or copy thesepictures,follow theinstructionsat www.usborne-quicklinks.com Internet safety WhenusingtheInternet,pleasefollow the safetyguidelinesdisplayedontheUsborne QuicklinksWebsiteat www.usbornequicklinks.com. Thewebsitesdescribedin thisbook andlistedinUsborneQuicklinks areregularlyreviewed,but Usborne Publishingisnot responsiblefor the availability or content of anywebsiteother thanitsown. Microscope andX-raypictures Many of themicroscope andX-rayimages inthisbook,suchastheoneontheleft, havehadextracolor addedto themto makethemclearer.Theydo not always show therealcolorsof thehumanbody. Contents 6BodyBuildingBlocks 8Youramazingbody 1 0Body systems 12Cells 14GenesandDNA 16MusclesandBones 1 8Theskeleton 20Joints 22Musclesandtendons 24How muscleswork 26Moving without thinking 28Reflexes 29Skin,Hair andNails 30What isskin? 32Skinchanges 34Hair andnails and the Senses 38 YOl:J r amazingbrain """iO;40How thebrainworks 42Seeing 44Hearing 46Tastingandsmelling 48:''''Sensationandpain 50Thinking 52Foolyour brain 53Breathing andCirculation Breathingequipment 6Inside your lungs 58Theheart 60Circulation In theblood '64Thelymphatic system 65EatingandDrinking 66Takinginfood 68Inyour stomach 70Intheintestines 72Waste 7 4HealthandMedicine 7 6Healthandsickness 78Diseases 80Theimmune system 82Drugsandtreatments 84Operations 86Complementary medicine: 87Body Changes 88Conceptionandbirth 90Growingup 92Hormones 94Gettingold 96FactsandFigures 98Facts,figuresandrecords 1 00Timeline 101Who'swho 102Experimentsandactivities 104Glossary 108Index 112Acknowledgements TheX-rayonthispage shows theribs,backboneand collarboneinsideahumantorso. Body BuildingBlocks Thehumanbodyisamazinglycomplicated. It'smadeupofhundredsofdifferentorgans, tubes,tendons,tissuesandotherbodyparts, eachwithitsownjobtodo.Inturn,these partsaremadeupofmillionsofmicroscopic unitscalledcells.Insidecellsarethesmallest bodypartsofall- thegenesthatmakeus human.Theytellcellshow todoallthe thingstheyneedtodotomakeourbodies workandkeepusalive. Almostevery cellinyourbody containsaset ofchromosomes, where your genes are stored.Inthe set shown onthe opposite page,thelastpairofchromosomesmatch,showingthat they came fromafemale .Inamale,thelastpair .ofchromosomes donotmatch,andthepairiscalledXYinsteadofXX. Youramazingbody Thehumanbody isanamazingmachine.Even thoughyourarelythink about it,your body isalwaysbusy.Youhavedozensof different organs,massesof musclesandbones,miles of bloodvessels,millionsof cells,anda brainmorepowerfulthananycomputer, allworkingtogether tokeepyoualive. Bodyparts Yourbody ismadeupof manydifferent partsand substances.Herearethe mainones: Organs arebody partsthat do a particular job for therest of your body.Forexample, your braincontrolsyour body,andyour lungscollect theoxygenyour bodyneeds. Body tissues include fat, boneand muscle. Body fluids.Your body containsmany different fluids(liquids). Bloodisthemost important one.Theothersinclude tears, sweat,andstomachjuices. Water makesup70%of your body.It'sfoundinyour blood,andinandaroundthe cellsthat makeup your body. Your brain,eyes andskin arealiexampl esof organs. Skinis the biggestorgan of all.It covers andprotects your whole body. Redblood celi s,an important part of bl ood, shown atabout 3, 000 times life-size. GOINGWRONG : Bodybreakdowns Although your body is amazing,it cango wrong. Lookout for theseGoing Wrongboxesthroughout thebook.Theyexplainall kindsof body breakdowns andproblems,likewhat causesa heart attack,why teenagersget zits,and what makesyouvomit. Thebodypartsinthis picturehavebeen Eyea coloredsoyoucantellNose,; themapart.Inreallife, most body partsare pink or reddish-purple. Skin Nervescarrymessages betweenthebrain andthebody. Thespineisa columnof bonesin theback. Thesebonesformthe centralpart of theskeletonand protect thespinalcord,whichhangs downfromthebrainandcarries information toandfromthebody. Humerus(upper armbone) r:'. Joint - a linkbetween bonesthat allowsthem tomove andflex. * Smallintestine Thekidneysareinthe middle of theback. They filter wasteLargeintestine chemicalsfrom your blood Radius(forearmbone) andcontroltheamount of water inthebody.Ulna(forearmbone) Carpals(wrist bones) Bloodvessels..... ,t Metacarpals(handbones) ..