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