Anatomy & PHYSIOLOGY Cardiovascular System

Anatomy & Physiology of Heart as preparation for Nursing studenta

1. Nor Masita Esa
UniversitiKebangsaanMalaysia

2. Attheendofthesession,thestudentsshouldbeableto:
▪Identifythemajorstructuresandfunctionsofthecardiovascular
system.
▪explainthecirculationofbloodthroughtheheartandcoronary
vessels.
▪definethecardiacoutputandcardiaccycle.
▪nameandlocatetheelementsofheart’sconductionsystem.

3. ▪Theheartisamuscularpump;itbeatsanaverageof70
timesperminute.
▪Thiscontinuespumpingmovesbloodthroughthebody
nourishingtissuecellandbody,removingwastes.Deficitin
thestructureorfunctionoftheheartaffectallbodytissue
andmaylimitalmostallhumanfunctions.

5. Shape
▪Theheartisahollow,cone-shapeorganapproximatelythe
▪Sizeofanadult’sfist.
Weight
▪200to425gram
Location
▪Mediasternumofthethoraciccavity
▪Betweenthevertebralcolumnandthesternum
▪Flankedlaterallybythelungs
▪Two-thirdsoftheheartmassliestotheleftofthesternum
▪Theupperbaseliesbeneaththesecondrib
▪Thepointedapexapproximatelywiththe5thintercostalsspace,midpointtotheclavicle.

7. ▪Coveredbyadoublelayeroffibroserousmembrane(pericardium).
Thepericardium:
▪encasestheheartandanchorsittosurroundingstructures,formingthepericardial
sac.
▪preventstheheartfromoverfillingwithblood.
▪theparietalpericardiumistheoutermostlayer.
▪thevisceralpericardiumorepicardiumadherestotheheartsurface.
▪thesmallspacebetweenvisceralandparietallayers-pericardialcavity.
▪serouslubricatingfluidproducedinthisspacecushionstheheartasitbeats.

8. ▪Threelayers:
1.Epicardium
•theoutermostepicardium
•samestructureasthevisceralpericardium.
2.Myocardium
•themiddlelayeroftheheart
•consistsofspecializedcardiacmusclecell(myofibrils)–providethe
bulkofcontractileheartmuscle.
3.Endocardium
•theinnermostlayer
•sheathofendothelium-linestheinsideoftheheart’schamberand
greatvessels

10. ▪Fourhollowchamber
-twoupperchambercalledatrium
-twolowerchambercalledventricles
•Separatedbyseptum.
•Eachoftheheart’schambersisseparatedbyavalve.
•Theatriumsareseparatedfromtheventriclesbytwoatrioventricular(AV)valve.
-Thetricuspidvalve-rightside
-Thebicuspidormitralvalve–leftside.
-Theflapsofeachofthesevalvesareanchoredtothepapillarymusclesoftheventriclesby
thechordaetendineae.
•Theventriclesareconnectedtotheirgreatvesselsbysemilunarvalves.
-Ontherightthepulmonaryvalvejoinstherightventriclewiththepulmonaryartery.
-Ontheleft,theaorticvalvejoinstheleftventricletotheaorta.

12. ▪SystemicCirculationconsistsof:
–Leftsideoftheheart
–Aortaanditsbranches
–Capillaries–supplythebrain&peripheraltissues
–Systemicvenoussystem
–Venacava
*Thesystemicsystem–movebloodtoperipheralareasofthebody
highpressuresystem

13. ▪PulmonaryCirculationconsistsof:
–Rightsideoftheheart
–Pulmonaryartery
–Pulmonarycapillaries
–Pulmonaryvein
*Locatedinthethoraxneartheheart,thepulmonarycirculationisa
low-pressuresystem.

15. ▪CoronaryCirculation
–Theheartmuscleitselfissuppliedbyitsownnetworkofvessels.
Theleft&rightcoronaryarteriesoriginateatthebaseoftheaortaand
branchouttoencirclethemyocardium,supplyingblood,O2and
nutrientstothemyocardium.
-Theleftmaincoronaryarterydividestoform
•anteriordescendingarteries
•circumflexarteries

16. •Theanteriordescendingartery:
–suppliestheanteriorinterventricularseptumandtheleftventricle.
•Thecircumflexbranchsupplies:
–Leftlateralwalloftheleftventricle
•Therightcoronaryartery(RCA)supplies:
–Rightventricleandformstheposteriordescendingartery(PDA)
–PDAsupplies–posteriorportionoftheheart.

18. ▪While ventricular contraction delivers blood through the pulmonary and systemic
circulation, during ventricular relaxation the coronary arteries fill with O2-rich
blood
• After the blood perfuses the heart muscle, the cardiac veins drain the blood into the
coronary sinus, which empties into the right atrium of the heart.
• Blood flow through the coronary arteries is regulated by:
▪–Aortic pressure
▪–Heart rate
▪–Metabolic activity of the heart
▪–Blood vessel tone (constriction)

19. ▪Cardiac cycle
–The contraction and relaxation of the heart constitutes one heartbeat.
-Thus cardiac cycle consists of systole and diastole of the atria plus systole and diastole
of the ventricles
▪Atrial Systole (lasts about 0.1sec)
-The atria are contracting at the same time ventricles are relaxed
-Depolarization of SA node causes atrial depolarization and marked by P Wave in the
ECG
-Atrial depolarization causes atrial systole, they exert pressure on the blood within ,
which forces blood through the open AV valves into the ventricles
-End Diastole Volume (EDV) : the blood volume contains in the ventricles at the end of its
relaxation period.

20. ▪VentricularSystole(Lastabout0.3sec)
-markedasQRScomplexintheECGonsetofventricular
depolarization
-Theventriclesarecontracting,atthesametime,atriaarerelaxedin
atrialdiastole
-Ventriculardepolarizationcausesventricularsystole
-Pressurerisesinsidetheventriclesandpushesthebloodupagainst
theatrioventricular(AV)valves,forcingthemshut.BothAVand
SemilunarValvesareclosedabout0.05sec.Thisisperiodof
Isovolumetriccontraction.Cardiacmusclearecontractingand
exertingforcebutarenotyetshortening

21. -Continuedpressureintheventriclescausespressureinsidethe
chambertorisesharplyandbothSemilunarvalvesopenand
ejectionofthebloodfromtheheartbegins.Thisperiodiscalled
VentricularEjection
-Bothventriclesejectsabout70mlsbloodintotheaortaand
pulmonarytrunk.Thevolumeremainingineachventricleattheend
ofsystoleabout60mlscalledEnd-systolicVolume(ESV)

22. -StrokeVolume,thevolumeejectedperbeatfromeachventricle
-SV=EDV–ESV(about130mls–60mls=70mls)
▪RelaxationPeriod(lastsabout0.4sec)
-TwaveintheECGmarkstheonsetofventriclerepolarization
-Bothatriaandventriclesarerelaxed
-Ventricularrelaxationcausesventriculardiastole.Astheventricles
relaxedthepressureinthechamberfallsandbloodintheaortaand
pulmonarytrunkbeginstoflowbackwardtowardtheregionsoflower
pressureintheventricle
-TheSLvalvesclosesasthevalvecuspscatchesthebackflowingofthe
blood

23. -Isovolumetricrelaxation,periodwhenthefourvalvesareclosedand
theventriclebloodvolumedoesnotchange.
-Ventricularfillingbeginsastheventriclecontinuetorelaxandthe
pressurequicklyfallsanddropbelowatrialpressureandtheAV
valvesopen.Attheendofrelaxationperiod,theventriclesareabout
three-quarterfull.

26. ▪Thereare4heartsounds:
-Thenormalheartsoundareonlythefirstandsecondheartsound(S1
andS2)
-S1describedasLubblouderandbitlongerthanS2.Causedby
bloodturbulenceassociatedwithclosureoftheAVValvesoonafter
theventricularsystolebegins
-S2canbedescribedasdubshorterandnotloudasfirstheartsound
causedbybloodturbulenceassociatedwithclosureofSLvalves.
-S3isduetobloodturbulenceduringrapidventricularfilling
-S4isduetobloodturbulenceduringatrialsystole

27. ▪Cardiacoutput(CO)
–theamountofbloodpumpedbytheventriclesintothepulmonaryandsystemic
circulationin1minute
–TheaverageadultCO-4to8l/min
CO=SVXHR
▪Ejectionfraction(EF)
–thepercentageoftotalbloodintheventricleattheendofthediastoleejectedfrom
theheartwitheachbeat.
–ThenormalEF-50to70%.
–COisanindicatorofhowwelltheheartisfunctioningasapump.

28. ▪Preload
–theamountofcardiacmusclefibertensionorstretchthatexistsattheendof
diastole,justbeforecontractionoftheventricles.
▪Afterload
–theforcetheventriclesmustovercometoejecttheirbloodvolume.
–pressureinthearterialsystemaheadoftheventricles.
▪Contractility
–theinherent(natural)capabilityofthecardiacmusclefiberstoshorten.

29. ▪Sinoatrialnode(SAnode)
–‘pacemaker’oftheheart
–generatinganimpulse60to100times/min
–thisimpulsetravelacrosstheatriaviainternodalpathwaystotheatrioventricular
(AV)node,intheflooroftheinteratrialseptum
▪Atrioventricular(AV)node
–theverysmalljunctionfiberoftheAVnodeslowstheimpulse,slightlydelayingits
transmissiontotheventricles.
▪BundleofHis
–ItthenpassesthoughthebundleofHisattheatrioventricularjunctionand
continuesdowntheinterventricularseptumthroughtherightandleftbundle
branchesandouttothePerkinjefibersintheventricularmusclewalls.

32. THANK YOU