Week 4 Flashcards
embryonic heart tube formation
forms from mesoderm in the 3rd week (days 18-22)
angioblasts
endocardial cells that differentiate from mesorderm in the formation of the heart tube surrounded by myoblasts
Truncus Arteriosis forms which adult structure(s)?
proximal aorta and pulmonary trunk
Bulbus Cordis forms which adult structure(s)?
Conus Arteriosis (RV), Aortic Vestibule (LV), and Trabeculated RV
Primitive Ventricle forms which adult structure(s)?
trabeculated LV
Primitive Atrium forms which adult structure(s)?
trabeculated RA and trabeculated LA
Sinus Venosus forms which adult structure(s)?
smooth RA and Coronary sinus
What’s the order of the regions of the embryonic heart?
top to bottom:
T B V A S
Truncus Arteriosus, Bulbus Cordis, Primitive Ventricle, Primitive Atrium, Sinus Venosus.
Arterial end at the top, Venous end at the bottom, BVA in the middle
What direction does the ventricular region of the heart move in “looping”?
ventrally, caudally, and to the right
What direction does the atrial region of the heart move in “looping”?
dorsally, cranially, and to the lefrt
What structures are required for “looping”?
cilia and dynein
What veins carry blood from the yolk sac to the heart?
vitelline veins
What veins carry blood from the placenta to the heart?
umbilical veins
What veins carry blood from the embryo to the heart?
cardinal veins
When does septation occur in the embyonic heart?
between 27-37 days
What occurs in septation of embryonic heart?
the single primitive atrium, ventricle, and outflow tract (truncus arteriosus) are separated by formation of septa (walls)
What is septum primum?
it grows from the roof of the common atrium down toward the atrioventricular canal
When does Septum Primum begin to form?
at the end of the 4th week
What is the foramen primum?
The septum primum does not form completely at first, leaving this foramen
What is foramen secundum?
Before foramen primum closes, cell death occurs in the septum primum forming this foramen secundum
What is septum secundum?
It form to the right of the septum primum, but also does not form completely
What is foramen ovale?
an opening in the septum secundum that allows blood flowing in from the IVC to push agains the septum primum and pass directly from the right atrium to the left atrium through the foramen secundum
What can cause atrial septal defects to occur?
If the septum secundum doesn’t grow enough or if the foramen secundum is too large
What are endocardial cushions?
They are proliferating endocardial cells on the dorsal and ventral walls of the heart. They grow toward each other and fuse, separating the single opening into 2.
They also form the atriventricular valves