1. The human body has three main layers of skin - the epidermis, dermis, and subcutaneous fat layer. The skin protects the body and helps regulate temperature. 2. Bones give the body structure and allow movement. Muscles help the body move. The digestive system breaks down food for nutrients. 3. The respiratory system includes the lungs, which take in oxygen, and the heart and circulatory system, which pump blood through arteries and veins to supply cells with oxygen and nutrients.

1. Unit 1:The Human Body

2. Vocabulary skin epidermis dermis pores subcutaneous digestion Fromthetextbook: producer consumer foodchain predator prey food web

3. YourSkin Itcovers and protectseverythinginsideyourbody. Yourskinisthelargestorgan in yourbody. It: protectsourbodies, helpskeepourbodies at justtherighttemperature allowsustohavethesense of touch

4. TheThreeLayers of theSkin

5. FirstLayer: Epidermis Thelayeroutsideiscalledtheepidermis. The epidermis isthepart of yourskinyou can see.

6. The Dermis isUnderthe Epidermis The dermis tellsyouhowthingsfeelwhenyoutouchthem. Sweat comes up throughpores, tinyholes in theskinthatallowitto escape.

7. SubcutaneousFat Itisthethirdlayerof theskin. Itismade of fat and helpsyourbodystaywarm and absorb shocks, likeifyoufalldown. Thislayeriswhereyouwillfindthestart of hair, too.

10. YourBones Bonesgiveyourbodystructure, letyoumove in manyways, protectyourinternalorgans, and more. Youhave206 bones.

13. Muscles Youhave more than600 muscles. You have three different types of muscles in your body: smooth muscle, cardiac (say: kar-dee-ak) muscle, and skeletal (say:skel-uh-tul) muscle.

17. DigestiveSystem Digestionallowsyourbodytogetthenutrients and energyitneedsfromthefoodyoueat. Digestionbegins in yourmouth.

18. Parts of theDigestiveSystem ESOPHAGUS Theesophagusislike a stretchy pipe that’sabout 10 inches (25 centimeters)long. Itmovesfoodfromthe back of yourthroattoyourstomach.

19. STOMACH Yourstomachis a stretchysackshapedliketheletter J. It has threeimportantjobs: 1. tostorethefoodyouhaveeaten 2. to break downthefoodinto a liquidy mixture 3. toslowlyempythatliquidy mixture intothesmallintestine

20. The Small Intestine Thesmallintestineis a log tubethatisabout 3.5 to 5 centimetersaround, and 6.7 meterslong. Thesmallintestinebreaksdownthefood mixture even more so yourbody can absorballthevitamins, minerals, proteins, carbohydrates, and fats. Itgetshelpfromthreefriends: thepancreas, liver, and gallbladder.

21. Liver Theliverfiltersoutharmfulsubstancesorwastes, turningsome of thewasteinto more bile. Theliverstorescertainvitamins and a type of sugaryourbody uses forenergy.

22. TheLargeIntestine Itisabout 7 to 10 centimetersaround. Itisfatterthanthesmallintestine and itisalmostthelast stop onthedigestivetract.

23. TheRectum Itistheverylast stop onthedigestivetract. Thesolidwastestayshereuntilyou are readytogotothebathroom.

26. TheRespiratorySystem LUNGS Yourlungs are in yourchest. Youhavetwolungs. Thelungontheleftside of yourbodyis a bit smallerthanthelungontheright. They are protectedbyyourribcage, whichismade up of 12 sets of ribs. Lungs are pink and a bit squishy, like a sponge.

27. TheDiaphragm Beneaththelungsisthediaphragm. Itis a dome-shapedmusclethatworkswithyourlungstoallowyoutoinhale (breath in) and exhale (breathout) air.

28. Trachea At thebottom of thetrachea, orwindpipe, there are twolargetubes. Thesetubes are calledthemainstembronchi, and oneheadsleftintotheleftlung, whiletheotherheadsrightintotherightintotherightlung.

29. Thetiniesttubes are calledbronchioles, and there are about 30,000 of them in eachlung. At theend of eachbronchioleis a specialareathat leads intoclumps of teenytiny air sacscalledalveoli.

32. YourHeart and CirculatorySystem Yourheartisreally a muscle. Itislocated a littletotheleft of themiddle of yourchest, and itisaboutthesize of yourfist. Theheartsendsbloodaroundyourbody. Thebloodprovidesyourbodywiththeoxygen and nutrientsitneeds.

33. HowDoestheHeart Beat? Beforeeach beat, yourheartfillswithblood. Thenitsmusclecontractstosquirtthebloodalong. Whentheheartcontracts, itsqueezes. Yourheartdoesthisallday and allnight, allthe time.

34. HeartParts Theheartismade up of fourdifferentblood-filledareas, and each of theseareasiscalled a chamber. There are twochambersoneachside of theheart. Onechamberisonthe top (atria) and onechamberisonthebottom (ventricles).

35. Circulation Bloodmovesthroughmanytubescalledarteries and veins, whichtogether are calledbloodvessels. Thesebloodvessels are attachedtotheheart. Thebloodvesselsthatcarrybloodawayfromtheheart are calledarteries. Theonesthatcarryblood back totheheart are calledveins. Ittakesyourheartlessthan 60 secondstopumpbloodtoeverycell in yourbody.