heart anatomy pdf.pdf

heart anatomy

1. ANATOMY AND
PHYSIOLOGY OF HEART
ANATOMY AND PHYSIOLOGY
OF HEART

2. THE HEART
Theheartisachamberedmuscularorganthatpumps
bloodreceivedfromtheveinsintothearteries,and
maintainsflowofbloodthroughtheentirecirculatory
system.
Ithasroughlythesizeofclosedfist.
Itliesinthemediastinumbehindsternumbetween4
th
and8
th
thoracicvertebrae.
Theweightoftheheartis225to300gmsinadults.
Heartistransverseinshapeforchildrenbutithas
normalpyramidalshapeinadultsby25years.

5. LOCATION OF HEART

6. LOCATION OF HEART
Thehumanheartislocatedwithinthethoraciccavity,
mediallybetweenthelungsinthespaceknownasthe
mediastinum.
Withinthemediastinum,theheartliesinitsown
spacecalledthepericardialcavity.
Thebaseoftheheartislocatedatthelevelofthe
thirdcostalcartilage.
Theinferiortipoftheheart,theapex,liesjusttothe
leftofthesternumbetweenthejunctionofthe
fourthandfifthribs.

7. Cont..
Theslightdeviationoftheapextotheleftisreflected
inadepressioninthemedialsurfaceoftheinferior
lobeoftheleftlung,calledthecardiacnotch.

8. COVERINGS OF HEART
Theheartissurroundedbymembranecalled
Pericardium.
Thepericardiumlieswithinthemiddlemediastinum.
Itsfunctionistorestrictexcessivemovementsofthe
heartasawholeandtoserveasalubricatedcontainer
inwhichthedifferentpartsoftheheartcancontract.

9. STRUCTURE OF HEART WALL

11. LAYERS OF HEART WALL
Epicardium:Theouterlayeroftheheart.The
termepicardiummeans“ontheheart”.Thisis
theviscerallayerofthepericardiumcalledas
serouspericardium.

12. Cont..
Myocardium:
a.Thisisthethick,contractile,middlelayerofthe
heart.
b.Theypossessinterconnectedmusclecelljunctions
calledsyncytiumfortheelectrical
connectionstowork.Itcanpassanaction
potentialfromfibertofiber.
c.Theinterconnectedmusclefibersalsohelpstohold
thehighpressuredbloodstronglyinsidetheheart.
d.MyocardiumisdamagedincaseofMIandcardiac
arrest.

13. Cont..
Endocardium:
a.Itisinnermostlayerofheartandmadeofendothelial
tissues.
b.Italsocoverthebeamlikeprojectionsofmyocardial
tissue.Theseprojectionsarecalledtrabeculae
carneaeandithelpstoaddforcetothecontractionof
heart.
c.Inwardfoldsorpocketsformedbytheendocardium
andconnectivetissuesarecalledvalves(AV&SL)which
preventsthereturnflowoftheblood.Thereare
tricuspidvalvesandbicuspidvalves.

15. CHAMBERS OF HEART
Theheartconsistsoffourchambers.
1.Rightatrium:Twolargeveinsdeliverde-
oxygenatedbloodtotherightatrium.Thesuperior
venacavacarriesbloodfromtheupperbody.The
inferiorvenacavabringsbloodfromthelowerbody.
Thentherightatriumpumpsthebloodtoright
ventricle.
2.Rightventricle:Thelowerrightchamberpumps
thede-oxygenatedbloodtothelungsthroughthe
pulmonaryartery.Thelungsreloadbloodwith
oxygen.

16. Cont..
3.Leftatrium:Afterthelungsfillbloodwith
oxygen,thepulmonaryveinscarrytheblood
totheleftatrium.Thisupperchamberpumps
thebloodtoleftventricle.
4.Leftventricle:Theleftventricleisslightly
largerthantheright.Itpumpsoxygen-rich
bloodtotherestofbody.

17. THE RIGHT ATRIUM
Rightborderoftheheart.
Itreceivesbloodfromthreeveins;superior
venacava,inferiorvenacavaandcoronary
sinus.
Thevalvebetweenrightatriumandright
ventricleiscalledtricuspidvalve/right
atrioventricularvalve.Itismadeofdense
cuspsofconnectivetissue.

19. THE RIGHT VENTRICLE
Receivesbloodfromtherightatriumthroughthe
tricuspidvalve.
Theedgesofthevalvecuspsareattachedtochordae
tendineaewhichare,inturn,attachedbelowto
papillarymuscles.
Thewalloftherightventricleisthickerthanthatofthe
atriaandcontainsamassofmuscularbundlesknownas
trabeculaecarneae.
Bloodflowsthroughthevalveandintothepulmonary
arteriesviathepulmonarytrunktobeoxygenatedinthe
lungs.

20. THE RIGHT VENTRICLE

21. The Left Atrium
Receivesoxygenatedbloodfromfour
pulmonaryveins.
Thewallsaresamethickasrightatrium.
The mitral(bicuspid)/left
atrioventricularvalveguardsthepassage
ofbloodfromtheleftatriumtotheleft
ventricle.

22. The Left Atrium

23. The Left Ventricle
Thewalloftheleftventricleisthickerthantheright
ventriclebutthestructureissimilar.Thisisthethickest
chamberoftheheart.
Itformstheapexoftheheart.
LiketherightventricleitalsocontainsTrabeculae
carneaeandchordaetendineaethatanchorthecusps
topapillarymuscles.
Bloodpassfromtheaorticvalve/semilunarvalveintothe
ascendingaorta.
Abranchoftheascendingaortacalledcoronaryartery
providesbloodsupplytothecardiactissues.

24. THE RIGHT VENTRICLE

25. The Heart Valves
Atrio-ventricularvalves
RightAV(Tricuspid):Separatestherightatriumfromthe
rightventricle.Preventsbackflowintoatrium.
LeftAV(Bicuspid):Separatestheleftatriumfromtheleft
ventricle.Preventsbackflowintoatrium.
Semi-lunar valves
Pulmonaryvalve:Separatestherightventriclefromthe
pulmonaryarteries.Preventsbackflowafterventricular
contraction.
Aorticvalve:Separatestheleftventriclefromtheaorta.
Preventsbackflowafterventricularcontraction.

28. Blood flow through the heart
Thebloodflowstartsfromrightatrium.
Thenitflowstorightventriclethroughatrio-ventricular/
tricuspidvalve.
Fromrightventricleitflowsthroughpulmonary
semilunarvalvesintothepulmonaryarteryandthento
pulmonarytrunk.
Thepulmonarytrunkbranchestoformrightandleft
pulmonaryarteryforgasexchangeatleftandrightlungs.
Fromlungstheoxygenatedbloodcomestoleftatrium
throughpulmonaryveins.
Fromleftatriumbloodflowsthroughmitralvalve/left
atrio-ventricular/bicuspidvalvetoleftventricle.

29. Cont..
Fromleftventriclebloodis
pumpedtoaortathroughaortic
valvethenthesupplygoesto
differentbranchestodifferent
partsofthebody.
Thevenousdrainagefrom
differentpartsofthebody
bringsdeoxygenatedbloodback
torightatriumthroughinferior
venacavaandsuperiorvena
cava.

31. CORONARY CIRCULATION

32. Arterial Supply of the Heart
Myocardial cells receive blood
supply from coronary arteries both
right and left.
The closure of aortic valve during
ventricular relaxation prevents the
backflow of the blood and fills the
coronary artery.
The arterial supply of the heart is
provided by the rightand left
coronary arteries, which arise from
the ascending aorta immediately
above the aortic valve.

33. Branches of Coronary Arteries
1. Right Coronary artery: Branches
Right marginal arteries.
Posterior descending artery
2. Left Coronary artery: Branches
Circumflex artery.
Left Marginal artery.
Left anterior descending artery
Diagonal branches

35. Venous Drainage of the Heart
Mostvenousbloodfrom
thecoronarycapillaries
drainintothecoronary
sinus,whichliesinthe
posteriorpartoftheatrio-
ventriculargroove.
Someveinsdonotenter
thesinusratheritdrainthe
venousblooddirectlyinto
rightatriumwithinferior
venacava.

36. Nerve Supply of the Heart

37. CARDIAC CONDUCTION SYSTEM
The cardiacconduction
systemisanetworkof
specializedcardiacmusclecells
thatinitiateandtransmitthe
electricalimpulsesresponsible
for the coordinated
contractionsofeachcardiac
cycle.

38. Cont..
Twotypesofcellscontrolheartbeat:
Conductingcellscarrytheelectricsignals.
Musclecellscontrolheart’scontractions.

39. Components of the Cardiac
Conduction System
1.Sinoatrialnode
2.Atrioventricularnode
3.Atrioventricularbundle (bundle of His)
4.Purkinje fibres

41. 1. SinoatrialNode
Sinoatrialnodeissometimescalledasheart’s
naturalpacemaker.Itsendstheelectrical
impulsesthatstarttheheartbeat.
TheSAnodeisintheupperpartofheart’s
rightatrium.Itisattheedgeofatriumnear
superiorvenacava.

42. 2. AtrioventricularNode
Theatrio-ventricularnodedelaystheSA
node’selectricalsignal.Itdelaysthesignalbya
consistentamountoftime(afractionofa
second)eachtime.
TheAVnodeislocatedinanareaknownas
thetriangleofKoch.Thisisnearthecentral
areaoftheheart.

44. 3. Bundle of His
ThebundleofHisisalsocalledthe
atrioventricularbundle.Itisabranchoffibers
(nervecells)thatextendsfromAVnode.
Thisfiberbundlereceivestheelectricalsignal
fromtheAVnodeandcarriesittothePurkinje
fibers.
ThebundleofHisrunsdownthelengthofthe
interventricularseptum.

46. Cont..
ThebundleofHishastwobranches:
Leftbundlebranchsendselectricalsignals
throughthePurkinjefiberstoleftventricle.
Rightbundlebranchsendselectricalsignals
throughthePurkinjefiberstorightventricle.

47. 4. Purkinje Fibers
ThePurkinjefibersarebranchesofspecialized
nervecells.Theysendelectricalsignalsvery
quicklytotherightandleftheartventricles.
WhenthePurkinjefibersdeliverelectrical
signalstotheventricles,theventricles
contract.

48. CONDUCTING SYSTEM OF THE
HEART

49. Conduction of Impulse in the Heart
Initiationofimpulse:ImpulseisgeneratedinSA
nodeatarateof70-80/minute.ThereforeSA
nodeiscalledaspacemakerofheart.

50. Cont..
Spreadofimpulse:
Thewaveofimpulsespreadstobothatriathrough
muscletissuessimultaneouslycausingthemto
contract.
FromSAnodeimpulsepassestoventriclesthrough
AVnode.
Uponreachingtheatrioventricular(AV)node,the
signalisdelayedby0.13seconds.
Thisdelaycausesventriclestocontractafteratrial
contractionisover.

51. Cont..
Itisthenconductedintothebundleofhis,downthe
interventricularseptum.
ThebundlebranchesandthePurkinjefibresspread
thewaveimpulsesatfastestratealongtheventricles,
causingthemtocontract.
Impulsegenerationandtransmissionisanelectrical
eventwhereascontractionandrelaxationofheart
musclearemechanicalevents.
Mechanicaleventsalwaysfollowelectricalevents.

52. Conduction of Impulse in the Heart