Development of the Heart Flashcards
What germ layer does the heart originate from and when does this start?
Splanchnic mesoderm originally located ventral to the pericardial coelom
Day 18
How does the endocardium form?
Paired endocardial heart tubes from splanchnic mesoderm
The tubes are brought together due to lateral folding of the embryo
The fuse in the midline to form a single heart tube (the endocardium)
What are the five dilatations of the heart tube?
Truncus arteriousus
Bulbus cordis
Primitive ventricle
Primitve atrium
Sinus venosus
Where does the sinus venosus receive blood from?
Paired umbilical veins
Paired vitelline veins
Paired common cardinal veins
What do the aortic arches originate from?
Truncus arteriosus
What is the atrioventricular canal?
Division between the primitive atrium an primitve ventricle
How does the atrioventricular canal get divided into left and right sides?
Dorsal and ventral endocardial cushions fuse to vorm the atrioventricular septum
What is the sino-atrial orifice?
Entrance of sinus venosus into the atrium
Shifts to the fight side of the atrium, therefore all venous blood enters
How does the primitive atrium divide?
The septum primum grows downward from the dorsal wall of the primitve atrium and fuses with the atrioventricular septum
What is the foramen ovale?
A passageway for oxygenated blood from the placenta entering the right atrium to be shunted to the left atrium
Allows bypass of nonfunctioning lungs
For what two reasons is the foramen ovale functionally closed after birth?
Decrease in right atrial pressure
Increase in left atrial pressure
What is the coronary sinus formed from?
Left horn of the sinus venosus
Describe the division of the bulbus cordis and truncus arteriousus
Bulbar and truncal ridges fust to form the aorticpulmonary septum, dividing the two structures into the ascending aorta and pulmonary trunk
How is the primitive ventricle divided?
The muscular ventricular septum forms from the floor of the ventricle and grows towards the atrioventricular septum, where it fuses and completely partitions the ventricle
What dilatation forms the upper smooth part the both ventricles?
Bulbis cordis
What dilatation forms the trabeculated part of both ventricles?
Primitive ventricles
What is the most common atrial septal defect?
Foramen secundum defect
Blood flows from the left atrium to the right atrium due to the higher blood pressure in the left atrium posnatally
What is a probe-patent foramen ovale?
Incomplete fusion of the sptum primum and septum secundum
Not pathological
What is a common atrium?
Total absence of development of the atrial septum
What is the result of a premature closure of foramen ovale?
Coses prenatally
Results in hypertrophy of the right side of the heart and underdevelopment of the left side
What is persistent atrioventricular?
Failure of endocardial cushions to fuse
Defects in atrial and ventricular septa resulting in single atrioventricular orifice
What results from a foramen primum defect?
Partial fusion of endocardial cushions results in a gap in the inferior part of the atrial septum
What is the most common congenital cardiac defect?
Membranous interventricular septal defect
Results from the failure of proper fusion of the three structures that form the membranous interventricular septum
Blood flows from the left to the right ventricle
What causes abnormal division of the truncus arteriosus?
Abnormal migration of neural crest cells into the bulbar and truncal ridges resulting in an abnormal aorticpulmonary septum
