CVS Embryology 1: Heart Development. Flashcards
When do angiogenic clusters appear?
In the middle of the third week.
What forms angiogenic clusters?
Mesenchymal cells in the splanchnic (vesiral) layer of the mesoderm proliferate and form isolated cell clusters known as angiogenic clusters.
Where are angiogenic clusters first located?
In the lateral side.
Where do angiogenic clusters rapidly spread to?
To the cephalic end.
The angiogenic clusters acquire what?
A lumen.
Angiogenic clusters unite to form what?
A horseshoe-shaped plexus of small blood vessels.
The anterior portion of the angiogenic plexus is called what?
Central portion of cardiogenic area.
The intraembryonic colemic cavity located over the blood vessel plexus later form what?
Pericardial cavity.
After formation of neural tube and brain vesicles CNS grown rapidly in which direction?
The cephalic direction.
What happens when neural tube and brain vesicles CNS grows rapidly in the cephalic direction?
It extends over the cardiogenic area and future pericardial cavity.
The percordial plate and the cardiogenic plate are pulled towards which direction?
Forward.
The cardiogenic plate and pericardial cavity become located where?
Ventrally and caudally.
List the 2 folds that bring the 2 heart tubes of an early embryo together?
1- folds in cephalocaudally (cranial fold).
2- then transversely (lateral fold).
The 2 endocardial heart tube in an early embryo fuse in which direction?
Cephalo-caudally.
The heart tube is attached to which side of the pericardial cavity?
Doral side of the pericardial cavity.
The heart tube of an early embryo is attached to the dorsal side of the pericardial cavity by what?
Dorsal mesocardium.
The mesoderm adjacent to the endocardial tube forms what?
Epimyocardial mantle.
The epimyocardial mantle is separated from endocardial tube by what?
Cardiac jelly.
The endocardial tube of an early embryo consists of what?
1- endocardium.
2- myocardium.
3- epicardium.
The cephalic portion of the heart tube bends in which direction which creates the cardiac loop?
Ventral and caudal direction to the right.
The caudal portion of the heart tube bends in which direction which creates the cardiac loop?
Shifts in a dorsal-cranial direction and to the left.
The 2 bends of the heart tube creates what?
A cardiac loop.
List the 4 twists of a primitive heart tube in order from top to bottom?
1- bulbus cordis.
2- ventricle.
3- atrium.
4- sinus venosus.
The atrioventricular junction remains narrow and develops into what?
Atrioventricular canal.
List the 3 parts of the bulbus cordis?
1- proximal third.
2- conus cordis (middle part).
3- truncus arteriosus (distal part).
What does the proximal third of the bulbus cordis form?
Forms the trabeculated (rough) part of the right ventricle.
What does the conus cordis (middle third) of the bulbus cordis form?
Forms the outflow tract (smooth side) of both ventricles.
What does the truncus arteriosus (distal third) of the bulbus cordis form?
Forms the aorta and pulmonary trunk.
The proximal portion of the bulbus forms what?
The primitive right ventricle.
The primitive ventricle become what to later form what?
Becomes trabeculated (rough) and forms the primitive left ventricle.
(Rough part of the left ventricle).
In which week does the sinus venosus consist of a transverse portion and right and left sinus horn?
4th week.
Each horn receives blood from 3 important veins, list them?
1- vitelline veins (venous drainage of the GIT).
2- the umbilical vein.
3- common cardinal vein (venous drainage of the whole body).
Which part of the horn disappears in the 5th and 7th week?
The left umbilical vein and left vitelline vein.
Which part of the horn disappears in the 10th week?
The left common cardinal vein.
List the remaining part un the left horn of sinus venosus?
1- the oblique vein of left atrium.
2- the coronary sinus.
Due to left to right shunt what happens to the right sinus horn and veins?
They enlarge.
What is the only communication between sinus venosus and the atrium?
The right horn.
The right horn is incorporated into right atrium to form what?
The smooth part of the right atrium.
What are endocardial cushions?
Dorsal (ant.) and ventral (post.) swellings.
Endocardial cushions fuse, dividing the single AV canal into what?
Paired canals.
Endocardial cushions are involved in the formation of what?
Formation of interatrial and interventricular septa.
Endocardial cushions are derived from what?
Neural crest.
Endocardial cushions are involved in which medical conditions?
In many CHDs (congenital heart diseases).
List the 5 arterial septums in order?
1- septum primum.
2- foramen primum.
3- foramen secundum.
4- septum secundum.
5- foramen ovale.
Septum primum grows from what?
Atrial roof toward endocardial cushions.
What is foramen primum?
Shunt that closes.
What does foramen secundum do?
Perforates septum primum, allowing shunt.
What does septum secundum do?
Grows down, overlapping foramen secundum.
Where is foramen ovale located?
Between septum primum and septum secundum.
How does foramen ovale close in a fetus?
1- right side high pressure (high pulmonary resistance, ect.).
2- well oxygenated blood streams through foramen ovale.
3- valve of foramen ovale closes with left atrial contraction.
What happens to foramen ovale after birth?
1- right side low pressure (low pulmonary resistance).
2- valve remains closed (physiological closure).
3- valve eventually fuses (anatomical closure).
What is foramen ovale called after it fuses?
Fossa ovalis.
Which partitioning is not part of fetal circulation?
Ventricular partitioning.
Ventricular septum closes in which week?
Week 7.
List the 2 types of ventricular septum?
1- muscular.
2- membranous.
Muscular IV septum grows from what?
Floor.
Membranous inter ventricular (IV) septum forms from what?
Endocardial cushions and bulbar ridges.
Closure of membranous IV is associated with what?
Partitioning of tuncus arteriosus.
Partitioning of truncus arteriosus is a continuous set of what?
Ridges in bulbus cordis (bulbar ridges) and truncus arteriosus (truncal ridges).
Partitioning of truncus arteriosus grow in which direction?
Towards each other, spiraling 180.
Partitioning of truncus arteriosus fuse to form what?
Spiraling aorticopulmonaryseptum, dividing aorta and pulmonary trunk.
Bulbular ridges are involved in the formation of what?
Formation of IV septum.
Bulbar and truncal ridges are derived from what?
Neural crest cells.
List the 2 types of VSD?
1- membranous (= perimembranous, conoventricular) VSD.
2- muscular VSD.
What is the most common CHD?
Membranous (perimembranous, conoventricular) VSD.
Membranous (perimembranous, conoventricular) VSD is more common among which gender?
Males > females.
What happens in membranous VSD?
Endocardial cushions and bulbar ridges fail to fuse with musc. septum.
Muscular VSD is located where?
In muscular IV septum.
What is the supracristal VSD?
Muscular VSD.
What is the least common VSD?
Muscular VSD.
List the 4 types of atrial septal defects (ASD)?
1- (ostium) secundum ASDs.
2- AV septal defect (AV canal).
3- patent foramen (ostium) primum.
4- sinus venosus ASDs.
What is the most common ASD?
(ostium) secundum ASDs.
(ostium) secundum ASDs is more common with which gender?
Females > males.
(ostium) secundum ASDs is due to what?
Problems with septum primum (perforated or too short), but sometimes septum secundum or both septa.
AV septal defect (AV canal) is due to what?
Endocardial cushion problems so that septum primum never fuses with cushion tissue.
A patent foramen (ostium) primum causes what?
Valve defects.
Patent foramen (ostium) primum is due to what?
Sometime no fusion of endocardial cushions: AV septal defects.
Patent foramen (ostium) primum is found in 20% of which patients?
Downs patients.
Which ASD is very rare?
Sinus venosus ASDs
Which CHD is 5-7% of all CHDs?
Tetralogy of fallot.
What is tetralogy of fallot?
Four co-occurring heart defects.
List the 4 co-occurring heart defects found in tetralogy of fallot?
1- pulmonary stenosis.
2- ventricular septal defect.
3- overriding aorta (dextroposition).
4- right ventricular hypertrophy.
Tetralogy of fallot is due to what?
Asymmetrical fusion of bulbar and truncal ridges.
