Thorax 06: Development Of Heart and Vessels Flashcards
Where does the splanchnic mesoderm lie before body folding?
Rostal to the buccopharyngeal-oropharyngeal membrane
What embryonic tissue eventually becomes the heart?
Mesenchyme
Where does heart development signalling come from?
Foregut floor
[Blank] can migrate into the heart and contribute to its development
Neural crest cells
Endocardium
Endothelium of the heart
Myocardium
Middle epithelial layer of the heart
Epicardium
Outer epithelia of the heart
Dorsal mesocardium
The mesentery of the heart that connects it to the foregut. The venous return to the heart traverses it
When do the two heart tubes from? When do they fuse?
They form in the 3rd week when the heart is folded caudally underneath the foregut floor. They fuse in the 4th week
Cardiac jelly
ECM secreted by the myocardium that lies between the endocardium and myocardium
Epimyocardium
Refers to the epicardium and myocardium together. Also known as myoepicardium
What regions does a single heart tube differentiate into?
Sinus venous, primitive atrium, primitive ventricle, conus arteriosus, truncus arteriosus
In the primitive heart, what is the flow of blood?
Sinus venous -> primitive atrium -> primitive ventricle -> conus arteriosus -> truncus arteriosus -> aortic sac -> aortic arches
How does the heart tube fold in week 4?
Primitive ventricle and conus arteriosus lie ventrally and to the left. Sinus venous and primitive atrium lie dorsally. Top folds down and bottom folds up
Where do arteries come out of? Where do veins go in to?
Arteries come out of front and veins go in from back. Nothing goes in the front or the bottom of the heart because of folding
What are the four chambers of the heart?
Right atrium, right ventricle, left atrium, left ventricle
Atrioventricular canal
A canal that forms between the primitive atrium and primitive ventricle
How is the atrioventricular canal partitioned?
Dorsal and ventral walls fuse, creating right and left AV canals. These canals act as valves
Septum primium
The first membrane that forms to split off right and left atria. It grows from the roof and makes its way towards the fusion of the endocardial cussions
Foramen primium
A gap that acts as a shunt between the right and left atrium during development. It is bordered superiorally by the septum primium and disappears when the septum primium fuses with the endocardial cushions
Foramen secundum
Gaps in the spetum primium that are caused by apoptosis of the septum, replacing the foramin primium
Septum secundum
A septum that grows from the ventrocranial wall to overlap foramen secundum
Foramen ovale
A valve formed in the septum secundum giving passage to oxygenated blood from the placenta, allowing it to bypass the pulmonary circuit. It fuses shut at birth
Fossa ovalis
The remnant of the foramen ovale after it is fused shut
How is the smooth wall of the left atrium formed?
It absorbs pulmonary vein tissue as the heart grows out. This results in separate pulmonary veins feeding into the left atrium directly and not a vein stem
Interventricular septum
A muscular septum that grows from cranially from the ventricular floor to partition the primitive ventricle
Interventricular foramen
Foramen that form in the interventricular septum
When and how do the interventricular foramen close?
In week 7 by the fusion of the interventricular septum with the endocardial cushions
Septation
Partitioning of the outflow tract
Where do bulbar and truncal ridges originate from?
Neural crest cells
Aorticopulmonary septum
The fusion of bulbar and truncal ridges that separates the aorta from the pulmonary trunk
How many aortic arches are there?
6
What happens to aortic arches 1 and 2?
They contribute to maxillary arteries
What happens to aortic arch 3?
It becomes common carotid and the base of internal carotid arteries on both sides
What happens to aortic arch 4?
It becomes part of the aortic arch and proximal subclavian artery
What happens to aortic arch 5?
It involutes
What happens to aortic arch 6?
It becomes ductus arteriosus and central part of pulmonary trunk
What happens to the recurrent laryngeal branches?
Right RL nerve passes under right subclavian artery. Left RL nerve passes under aortic arch and behind ductus arteriosus
What happens to the vitelline veins?
They are captured by the liver in week 7 and become the portal vein
What happens to the umbilical veins?
Right one involutes, left one develops into ductus venosus
Ductus venosus
A shunt that forms to send blood through liver to inferior vena cava
Brachiocephalic vein
Formed by the anastomosis of the left and right cardinal veins to shunt blood to the right side of the body
Where does the coronary sinus form from?
sinus venosus
How does the foramen ovale close?
With respiration, there is decreased resistance in lungs, opening the pulmonary artery. The pressure differences closes the ovale and forms the fossa ovalis
How does the Ductus arteriosus close?
Lung releases bradykinin which causes constriction of the smooth muscle of DA; additionally, levels of prostaglandin E decrease because there is no placenta so the DA closes
Atrial Septal defects
Any set of disorders where the spetum do not properly divide the primitive atirum
Ventricular septal defects
Any set of disorders where the septum do not properly divide the primitive ventricle
Tetralogy of Fallot
Results from:
1) pulmonary trunk stenosis
2) hypertrophy of the right ventrical wall
3) High ventricular septal defects
4) Overriding aorta
It is related to the unequal division of the conus arteriosus
Patent ductus arteriosus
The flowing of blood from the aortic arch to the pulmonary trunk due to the distal part of the 6th aortic arch failing to involute
Aortic coarctation
Narrowing of the aorta and can be deadly if it is post-ductus
Truncus arteriosus
Incomplete separation of truncus and conus leading to fistulas between the aorta and pulmonary trunk
Endocardial cushions
Structures that bulge out and develop to partition the atria from the ventricles
What cells help form the aorticopulmonary septum
Neural crest cells
What do the umbilical arteries become in the adult?
The medial umbilical ligaments and superior vesicular arteries
