PARTTWO–CIRCULATORYSYSTEM

Attheendofthissec;onyoushouldbeableto:Namethepartsofthecirculatorysystem,(heart,vessels).ExplaintheroleofthecirculatorysystemDescribethefunc<onofthemainparts,(heartvessels).

AnatomyoftheCirculatorySystem

•  Therearethreemainpartsofthecirculatorysystem:–  Theheart–  Bloodvessels–  Pulmonaryandsystemiccircula<on

•  Theheartisthepumpthatkeepsbloodcircula<nginourbloodvessels.

•  Thebloodvesselsarebrokendownintomanytypes,mainlydependingontheirsize.

•  Therearetwowaysthatbloodcirculatesthroughoutthebody.

BloodVessels

•  Thebodiesbloodvesselsformaclosed-circuitnetwork.

•  Bloodvesselsaredividedintothreecategories:– Arteries– Capillaries– Veins

Arteries•  Abloodvesselthat

carriesbloodfromthehearttootherpartsofthebody.

•  Theyhaveverythickwalls,allowingthemtowithstandhighamountsofpressure.

•  Theybranchintosmallerarterioles,beforebecomingsmallcapillaries.

Capillaries

•  Abloodvesselthathasasmalldiameterandthinwalls.Responsibleforexchangesbetweenthebloodandcells.

•  Capillariesaresosmallthatthebloodcellsmustpassoneata<me.

Veins

•  Abloodvesselthatcarriesbloodbacktotheheart.

•  Oncecapillariesstarttoreconnect,theyformvenules,whichbecomethelargerveins.

TheHeart

•  Theheartisroughlythesizeofyourfist,locatedbetweenyourlungs,protectedbytheribcage.

•  Itiscomposedoffourchambers:– Rightatrium– Rightventricledirectlylinked– LeQatrium– LeQventricledirectlylinked

Separatedbyapar<<on

…

•  Thereare5majorbloodvesselsthatareconnectedtotheheart.– Superiorandinferiorvenacava,(veins)– Pulmonaryvein– Pulmonaryartery– Aorta,(artery).

…

•  Valvesarealsopresentintheheart.•  Withoutthesevalves,bloodwouldflowbackwardsintheheart.Theyarecalledatrioventricularvalves.

•  SeveralbloodvesselsareaUachedtotheheart.–  Veins,(superiorandinferiorvenacava,pulmonaryveins),aUachedtobothatria.

–  Arteries,(aortaandpulmonaryarteries),areaUachedtotheventricles.

Func<onoftheHeart

•  Thecontrac<onandrelaxa<onoftheheartmusclesiswhatcirculatesbloodthroughoutthebody.

•  Forbloodtoentertheheart:–  Itmustentertheatriafromtheveins.–  Itmustenterwhentheheartisatrest,orisrelaxed.

– Thefillingoftheheartiscalleddiastole.

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•  Forbloodtoleavetheheart:–  Theatriamustcontract,pushingbloodintotheventricles.

–  Then,theventriclescontract,pushingbloodintothearteriesaUachedtotheheart,(aortaandpulmonary).Thisiscalledsystole.

•  Thepulsethatyoufeelcorrespondstothecontrac<onsoftheleQventricle,(itislarger).75beatsperminutewhenatrest.

Circula<onRoutes

•  Theheartisadoublepump.Becausethetwosidesoftheheartareseparated,thebloodispumpedinandoutbydifferentroutes.

•  Ontherightsideoftheheart,themechanismiscalledpulmonarycircula;on.

•  OntheleQside,itiscalledsystemiccircula;on.

Pulmonaryvs.SystemicPulmonary

•  Rightside.•  Shortercircuit.•  BloodisrichinCO₂•  Bloodexitstherightventricle

andflowstothecapillariesofthelungs.

•  CO₂exchangeswithO₂.•  NowrichinO₂,bloodreturns

totheheartandenterstheleQatriumthroughapulmonaryvein.

Systemic

•  LeQside.•  Longercircuit.•  BloodisrichinO₂.•  BloodexitstheleQventricle

throughtheaorta.•  Aortadividesintoarteries

andcapillarieswhichshedO₂atthecellsandpickupCO₂.

•  NowrichinCO₂,bloodreturnstotheleQatrium,enteringviatheVenaCava.

Circula<onRoutes