Cardiovascular Development Flashcards
Nkx2.5
Homeobox gene req for normal cardiac development
Which direction does fetal blood flow/does the heart develop?
caudal to rostral
What is looping?
Twisting of the heart pushes the future atria from caudal position to a more rostral and posterior position.
What is myocardial trabeculation?
Differentiation of pulmonary and aortic tubes, occurs at the same time as looping
What does the bulbus cordis become?
Conus cordis
-cardiac outflow tract (transient structure that connects the ventricles to the aortic sac)
Truncus arteriosus
-Pulmonary artery and aorta
What cells form the cardiac valves?
AV canal/endocardial cushions undergo epithelial to mesenchymal transition and migrate into the cardiac jelly
What is septation?
Process of separating the pieces of the heart
What is the septum primum?
Part of atrial septation. Grows from dorsal wall of atria towards the AV cushions (the hole that is not yet closed by the septum is called the ostium premum).
Small holes form in the septum premum towards the dorsal wall.
What is the septum secundum?
It grows outward from the superior wall of the atria, very close to the septum primum. This forms a second layer of tissue that also maintains a hole that is offset from the ostium secundum. These overlaid layers of tissue become the atrial septum, with holes forming the foramen ovale.
Ostium secundum ASD
Most common type of ASD. Occurs in center of septum between right and left atria.
Due to incomplete formation of the septum secundum or incomplete active closure of ostium secundum
Ostium primum ASD
Leads to problems with AV valves
Due to incomplete active closure of the ostium primum
Sinus venosus ASD
Least common, located in upper portion of atrial septum
Due to a defect in formation of septum primum and is often associated with an abnormal pulmonary vein being connected to RA instead of LA.
Which arch becomes the main aortic arch?
Left 4th arch, while the right 4th arch degenerates
What is DiGeorge Syndrome?
Chromosomal deletion that leads to defects in NC migration .Can include a patent truncus arteriosus (because NC cells are req for septation)
How is the L–>R axis thought to be determined?
By embryonic cilia
What is dextrocardia?
When heart is a mirror image–heart tube loops left instead of right, otherwise heart is normal. Fine as long as all organs are flipped also (situs inversus)
What is Heterotaxy?
When some organs are flipped and some are not. this is a problem
How are the valves formed?
Endothelial cells migrate into cardiac jelly and become mesenchymal cells. These groups of cells become endocardial cushions and eventually mature into valve leaflets.
What pathway governs valve formation?
Ras pathway
-link between leukemia and valvular diseases
What are semaphorins
key regulators of vasculogenesis that are repulsive signals of vasculature
What do cells in the epicardium contribute to?
Multipotent cells that give rise to fibroblasts in the heart, coronary arteries
