The human body contains multiple systems that work together to sustain life. These systems include the digestive, circulatory, nervous, respiratory, muscular, skeletal, urinary, reproductive, lymphatic, integumentary, and endocrine systems. Each system is comprised of organs and tissues that perform specialized functions to keep the body functioning properly.

1. Thehumanbodyismadeupofmultiplesystemsthatworktogethertoformlife.
Bodysystemsareanorganizedgroupoftissuethatformsaparticularfunction.
Thesefunctionsworkwithothersystemsinthebody.
Someofthemainsystemsofthebodyare:
 DigestiveSystem,
 CirculatorySystem,
 NervousSystem,
 RespiratorySystem,
 MuscularSystem,
 UrinarySystem,
 ReproductiveSystem,
 LymphaticSystem,
 IntegumentarySystem
 EndocrineSystem

2. Digestive System
Digestionisthesystemresponsibleforbreakdownofbiomolecules.Biomolecules
suchascarbohydrates(sugars),proteinsandlipids(fats)areabsorbedinthesmall
intestineanddeliveredtotheblood.Thedigestivesystemisalongpaththatstarts
fromthemouthandendsattheanus.Foodtravelsdowntheesophagustothe
stomach,wheregastricjuicesbegintheprocessofbreakdown.Thefoodissentto
thesmallintestine,wherepancreaticenzymesbreakdownfoodintosmaller
componentsforabsorption.Finally,wasteproductsaresenttothecolonand
excretedthroughtheanus.

3. CirculatorySystem
Thecirculatorysystemisresponsiblefordeliveryofoxygenandnutrientstothe
tissueintheorgans.Allcellsinthebodyrequireoxygenforcellularreactions.This
oxygen,alongwiththebiomoleculesfromthefoodsweeat,areusedtoproduce
energy.Theheartisalsoapartofthissystem.Theheartisresponsibleforretrieving
deoxygenatedblood,pumpingittothelungsandthensendingitthroughthe
arteriesthroughoutthebody.

4. NervousSystem
Thenervoussystemisthe"controlswitch"ofthebody.Thenervoussystemismade
upofthebrain,spinalcordandtheperipheralnervesthatspantolocations
throughoutthebody.Thenervoussystemretrievesenvironmentalinputsuchas
heat,touch,sound,andsightandsendsittothebrain.Thebrainprocessestheinput

5. andsendsoutputbacktothebodyusingefferentnerves.Thesenervesarewhat
controlreactionssuchaswalking,talkingandwavingarms.
Respiratory System
Therespiratorysystemisthepartofthebodythatprocessesgasexchange.When
thebodyinhales,theairfillsthelungs.Thealveoliinthelungsaresmallballoonsthat
fillwithair.Theseballoonsaresurroundedbycapillariesofdeoxygenatedblood

6. pumpedbytheheart.Thealveoligivesthebloodtheoxygenfrominhalingandthen
receivesthecarbondioxide,whichisawasteproductofmetabolism.Whenthe
bodyexhales,thecarbondioxideissentbackoutofthemouth,andtheprocessis
repeated.
MuscularSystem

7. Themuscularsystemisthemusclesthroughoutthebodythatcontrolmovement.
Mostpeopleinitiallylabelthemuscularsystemasthemusclesweknowonour
arms,legsandstomach.Thesemusclesarecalledskeletalmuscles.However,there
aretwoothermajorgroupsofmuscles.Smoothmuscleisfoundinplaceslikethe
esophagus,wherefoodispushedfromthemouthtothestomach.Smoothmuscleis
alsolocatedintheintestines.Theothertypeofmuscleiscardiacmuscle.Cardiac
muscleisfoundintheheart.

8. Skeletal System
Theadulthumanskeletalsystemconsistsof206bones,aswellasanetworkof
tendons,ligamentsandcartilagethatconnectsthem.Theskeletalsystemperforms
vitalfunctions—support,movement,protection,bloodcellproduction,calcium
storageandendocrineregulation—thatenableustosurvive.

9. Urinarysystem
Theurinarysystem,alsoknownastherenalsystem,produces,storesandeliminates
urine,thefluidwasteexcretedbythekidneys.Thekidneysmakeurinebyfiltering
wastesandextrawaterfromblood.Urinetravelsfromthekidneysthroughtwo
thintubescalleduretersandfillsthebladder.Whenthebladderisfull,aperson
urinatesthroughtheurethratoeliminatethewaste.

10. Reproductive System
Thereproductivesystemisacollectionofinternalandexternalorgans—inboth
malesandfemales—thatworktogetherforthepurposeofprocreating.Duetoits
vitalroleinthesurvivalofthespecies,manyscientistsarguethatthereproductive
systemisamongthemostimportantsystemsintheentirebody.

11. Lymphatic System
Thelymphaticsystemisanetworkoftissuesandorgansthathelpridthebodyof
toxins,wasteandotherunwantedmaterials.Theprimaryfunctionofthelymphatic

12. systemistotransportlymph,afluidcontaininginfection-fightingwhitebloodcells,
throughoutthebody.
Thelymphaticsystemprimarilyconsistsoflymphaticvessels, whicharesimilarto
thecirculatorysystem'sveinsandcapillaries.Thevesselsareconnectedtolymph
nodes,wherethelymphisfiltered.Thetonsils,adenoids,spleenandthymusareall
partofthelymphaticsystem.
Integumentary System

13. Theintegumentarysystemistheorgansystemthatprotectsthebodyfromvarious
kindsofdamage,suchaslossofwaterorabrasionfromoutside.Thesystem
comprisestheskinanditsappendages(includinghair,scales,feathers,hooves,
andnails).Theintegumentarysystemhasavarietyoffunctions;itmayserveto
waterproof,cushion,andprotectthedeepertissues,excretewastes,and
regulatetemperature,andistheattachmentsiteforsensoryreceptorstodetect
pain,sensation,pressure,andtemperature.Inmostterrestrialvertebrateswith
significantexposuretosunlight,theintegumentarysystemalsoprovides
forvitaminDsynthesis.

14. EndocrineSystem
Theendocrinesystemreferstothecollectionofglandsofanorganism
thatsecretehormonesdirectlyintothecirculatorysystemtobecarriedtowards
distanttargetorgans.Themajorendocrineglandsincludethepineal
gland,pituitarygland,pancreas,ovaries,testes,thyroidgland,parathyroid
gland,salivarygland,sweatglands,mammary
glands,hypothalamus,gastrointestinaltractandadrenalglands.Specialfeatures
ofendocrineglandsare,ingeneral,theirductlessnature,theirvascularity,and
commonlythepresenceofintracellularvacuolesorgranulesthatstoretheir
hormones.