SYBSC_Scoliodon_Heart_ppt.pdf,ccccccccccc

its about the circulatory system of scoliodon

1. Scoliodon: Blood Vascular System

2. Thebloodvascularsystemconsists:
1.Heart
2.Arterialsystem
3.Venoussystem.

3. Theheartislocatedbelowthepharynx.
Itisreddishbrown,conical,muscularorgan.
Itisenclosedinadoublelayered,
transparentmembranecalledpericardium.
Thereisaspacebetweentwolayersof
pericardiumcalledpericardialcavity.
Thepericardialcavityisfilledwith
pericardialfluid.
Thefluidservesasshockabsorberand
protectsfrommechanicalinjuries.
Italsoprovidesfreemovementstothe
heartduringcontraction.
Heart

4. Theheartisformedoftwochambers-
1.AuricleorAtrium
2.Ventricle
Alongwiththese,twoaccessory
chambersarealsopresent-
1.Sinusvenosus&
2.Conusarteriosus

5. 1.SinusVenosus:
•Itissomewhattriangular,elastic,thin-walled
chamber.
•Itissituatedonthedorsalsideofventricle
alongthebaseofpericardialcavity.
•Itreceivesvenousbloodfromtwolargeveins
calledCuvierianductsandtwohepaticsinuses.
•Thesinusvenosusopensintoauriclebysinu-
auricularaperture(Sinu-atricularaperture).
•Itisguardedbyapairofsinu-auricularvalves
(Sinu-atricularvalves).
•Thesevalvespreventthebackflowofblood
fromauricleintosinusvenosus.

6. 2.Auricle/Atrium:
•Itisalarge,triangularandthin-walledchamber
situatedinfrontofthesinusvenosus.
•Itopensintotheventriclebyauriculo-ventricular
aperture.
•Thisapertureisguardedbytwoliplikeauriculo-
ventricularvalves.
3.Ventricle:
•Itisprominentandconicalchamberwiththick
muscularwalls.
•Themuscularstrandscalledchordaetendinaeare
presentinitsinnersurface.
•Anteriorly,theventricleleadsintoatubular
structurecalledconusarteriosus.

7. 4.ConusArteriosus:
•Itisastoutmusculartubearisingfrom
ventricleandextendsuptotheanteriorendof
pericardialcavity.
•Theinnerwallisprovidedwithtwotransverse
rowsofsemilunarvalves.
•Theconusarteriosusleadsforwardinthe
formofatubecalledventralaortaorcardiac
aorta.
TheheartofScoliodoncontainsonlyimpure
blood,hencecalledasvenousheartor
branchialheart.

8. Workingofheart
Theheartservestopumptheblood.Forpumpingthe
bloodthereshouldbesufficientpressure.Thisis
broughtaboutbyrhythmiccontractioncalledsystole
andrelaxationcalleddiastoleofheart.

9. •Thebloodisreceivedfromvariouspartsofthe
bodyinsinusvenosus.
•Contraction(systole)startsfromthesinus
venosusforcingthebloodintotheatrium
(auricle)throughsinu-auricularaperture.
•Bythecontractionofauricle,thebloodreaches
theventriclethroughauriculo-ventricular
aperture.
•Inthemeantimethesinusvenosusisrelaxed
(diastole).
•Theventriclecontractsandforcesthebloodinto
conusarteriosus.
•Herebackflowofbloodispreventedbytworows
ofsemilunarvalvesinconusarteriosus.
•Fromconusarteriosus,thebloodentersthe
ventralaortaandthentogillsforoxygenation.

10. •Afteroxygenationthebloodisnotsentback
totheheartbutforcedtovariouspartsof
thebody.
•Thedeoxygenatedbloodagainreturnedto
theheartfromvariouspartsofthebody.
Thus,theheartiscalledvenousheartor
branchialheartandthecirculationiscalledas
singletypeofcirculation.