Flashcards
CVS embryology 2
Cards in this deck (29)
- 1Four stages of cardiac developmentPrimitive heart tube
Heart looping
Atrial and Ventricular Septation
Outflow Tract Septation - 2Formation of primitive heart tubesAngiogenic cell islands collect in lateral plate splanchnic mesoderm
Collection moves towards midline and coalesces to form two primitive heart tubes - 3When does primordial heart begin to function? Why?Start of 4th week
Rapidly growing embryo can no longer function by diffusion alone - 4How is cardiogenic field (primitive heart and vasculature) created?Blood vessels appear in wall of yolk sac, allantois, connecting stalk and chorion
Angioblastic cords appear in cardiogenic mesoderm around 3rd week; these canalise to form heart tubes - 5Where are the parts of the pericardium derived from?Pericardial cavity derived from intraembryonic coelom (gap between somatic and spanchnic mesoderm)
Parietal layer of serous pericardium and fibrous pericardium formed from somatic, visceral formed from splanchnic - 6What does cranial foldin of embryo cause?Pericardial cavity changes from dorsal to ventral
Cardiac tube changes from ventral to dorsal - 7Sections of fused primitive heart tube (cranial to caudal)Truncus arteriosus
Bulbus cordis
Ventricle
Atrium
Sinus venosus (right and left horns) - 8SInus venosus structure (horns)Two horns, right and left
Each horn receives venous blood from:
Yolk sac via vitelline vein
Placenta via umbilical vein
Embryo body via common cardinal vein - 9Truncus arteriosus structure (arches)Continuous cranially with aortic sac
Aortic arches arise in aortic sac, terminate in dorsal aorta - 10Formation of cardiac loop BulboventricularBulbus cordis and ventricle grow faster than other regions
U shaped bulboventricular loop forms around day 24
Bulboventricular sulcus between two regions - 11DextrocardiaHeart wrong way round (faces right, not left)
Due to heart looping to left, so facing right
Can be associated with situs inversus, transposition of viscera - 12Primordial heart partitioningBetween 27 and 37 days
Involves 1-2 actively growing tissue masses:
Endocardial cushion formation, seperating right AV opening from left forming L&R AV canals
Septum formation, separating left and right atria and left and right ventricles - 13Issues at stage of primordial heart partitioningMany cardiac malformations
ASD, VSD - 14Formation of canals
- 15Septum formationStarts towards end of week 4
Two septa, two foramina develop
(septum and foramen/ostium primum, septum and foramen/ostium secundum) - 16Formation of septum primumSickle shaped crest grows from atrium roof (septum primum)
Grows towards endocardial cushion between canals
Opening between the two: ostium primum - 17Foramen secundumCell death allows foramen secundum to form at upper end of septum primum
Septum secundam, a new fold, forms on the right of the original septum primum, overlapping ostium secundum
Foramen ovale forms in gap between two septa - 18Foramen ovalePerforates gap between two septa on side of septum secundum
Whereas ostium secundum perforates septum primum - 19Foramen in relation to septaForamen secundum=septum primum
Foramen ovale=septum secundum - 20Foramen ovale roleAllows most blood to bypass lungs, which cannot function yet (maternal blood also oxygen rich so no need)
Stops blood going backwards - 21Closure of foramen ovale after birthNormally closes; increased pulmonary blood flow shifts pressure to left atrium
Septum primum fuses with secundum
Fossa ovalis is remnant of FO
Non-closure=ASD (hole in heart) - 22ASDCommon congenital abormality
More common in females than males
Most commonly patent FO
Also defect in foramen secundum, endocardial cushion defect with foramen primum defect, sinus venosus defect, shared atrium - 23Ventricle partitioningMuscular ventricular septum forms
Opening is interventricular foramen
Aorticopulmonary septum rotates, fusing with muscular ventricular septum
IV foramen closed
Growth of endocardial cushions separates ventricles from atrial, also helps form membraneous portion of IV septum - 24VSDMore common in males
Most common congenital heart defect (25%)
Can appear in any part of septum
Can close spontaneously
Membraneous most common - 25Partitioning of bulbus cordis and truncus arteriosusActive proliferation of mesenchymal cells in walls of BC and TA
Bulbar and truncal ridges form
180 degree spiralling caused by streaming of ventricular blood leads to formation of aorticopulmonary septum
Divides BC and TA into aorta and pulmonary trunk - 26Conducting system of heartEarly; primordial atrium, then sinus venosus
SA node develops during week 5
In adults, SA node is high in right atrium near SVC entrance
AV node and bundle develop from cells of AV canal and sinus venosus - 27Issues associated with conduction systemCot death/SIDs
Conducting tissue abnormalities - 28Summary of heart tube fatesAortic sac=aortic arches
Bulbus cordis=right ventricle, pulmonary trunk
Primitive ventricle=left ventricle
Primitive atrium=left and right atria
Sinus venosus=superior vena cava and part of right atrium - 29Tetralogy of Fallot4 cardiac defects
Pulmonary stenosis (obstructed LV outflow)
VSD
Overriding aorta (dextropostion, blood flows in from both ventricles as opposed to just left)
RVH
Due to uneven division of conus, AP septum displaced anteriorly
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- Medicine Flashcards on CVS embryology 2, created by Phoebe Williams on 30/04/2018.
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- Phoebe Williams
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