22. Heart Tube and Septal Defects Flashcards
When does the fetal vascular system appear
Middle of the third week
Where do cardiac progenitor cells comes from?
Epiblast
What forms the primary heart field?
Cardiac progenitor cells from the splanchnic layer of lateral plate mesoderm
What arises from the primary heart field?
Atria, left ventricle, part of right ventricle
What forms the secondary heart field?
Cardiac progenitor cells from pharyngeal mesoderm
What arises from the secondary heart field?
Remainder of right ventricle and outflow tract
When does the heart tube begin to bend?
23 days
What is the cranial bulge called?
Bulbus cordis
What is the caudal bulge called?
Primitive ventricle
How does the heart bend?
Top bends towards the right Bulboventricular part becomes u-shaped Bulbus cordis forms right part Primitive ventricle forms left Junction is called bulboventricular sulcus
What does the proximal bulbus cordis become?
trabeculated part of the right ventricle
What does the conus cordis become?
Outflow tract of both ventricles
What does the truncus arteriosis form?
Roots and proximal portion of aorta and pulmonary artery
What is the sinus venosus?
Cavity which precedes as the SA node and coronary sinus
What does each sinus horn have?
Vitelline vein (left vanishes) Umbilical vein (right vanishes) Common cardial vein
Describe the formation of the septum primum
Sickle shaped crest grows from the roof of the common atrium
2 limbs of the septum extend towards endocardial cushions in the atrioventricular canal
Extensions of superior and inferior endocardial cushions grow along edge of septum primum to close the ostium primum
What is the name of the opening between the lower rim of the septum primum and endocardial cushions?
Ostium primum
Describe the formation of the septum secundum
Before the septum primum completely closes, cell death produces holes at the top
Holes join to form ostium secundum, ensuring free blood flow from right to left primitive atrium
The new crescent shaped fold is called the septum secundum
This begins to overlap with the ostium secundum
Opening is called foramen ovale
Upper part of the septum primum disappears
Passage left through atrial cavities with a cleft through which blood flows from the RA to LA
How is the ventricular septum formed?
Primitive ventricles expand
Medial walls merge, forming a muscular interventricular septum
Name 3 atrial septal defects
Left to right shunting of blood
Ostium primum defect
Ostium secundum defect
Name 5 ventricular septal defects
Ventricular spetal defect Left to right shunt Persistant truncus arteriosis Tetralogy of Fallot Transposition of the great vessels
