Heart Development - Bolender Flashcards
How is the heart tube arranged?
From Superior to Inferior:
Transverse Arteriosum
Bulbis Cordis
Primative Ventricle
Primative Atria
Which direction does the cardiac tube fold?
To the right
What disease occurs if the cardiac tube folds in the opposite direction? What is other disorders is this associated with?
Dextrocardia (heart on the right side)
Associated with situs inversus (reversed body) and TGA (transposition of the great arteries)
What joins with the primative atria? When does this happen?
The sinus venosum (specifically the right and left horn) Day 22
Which branch of the sinus venosum becomes dominant? What does this mean for circulation of the heart?
The right branch is dominant after the left branch atrophies and connects into the right branch. All deoxygenated blood now empties into the right ventricle.
After the right branch joins with the left branch, an anastamoses is formed between the right and left side. Which branches are involved?
Anterior Cardinal Vein of the Left Branch
Anterior Cardinal Vein of the Right Branch
What does the left branch of the sinus venosum form?
It atrophies into the coronary sinus.
What four branches come off BOTH the left and right sinus venosum?
Anterior Cardinal Vein
Posterior Cardinal Vein
Viteline Vein
Umbilical Vein
What do the following embryologic structures become: Anastamoses between Cardinal Veins Right Anterior Cardinal Vein Right Vitelline Vein Left Vitelline Vein
Left Brachiocephalic Vein
Superior Vena Cava
Inferior Vena Cava
It atrophies in adults
Where do the pulmonary veins come from?
They arise from the lungs (?) and fuse with the atria. They DO NOT arise from the sinus venosum.
How is the definitive left atrium formed? What is the exception?
Absorption of the endothelium of the pulmonary veins
The auricle, which is primative atria.
Where do the endocardial cushions form? What is their importance?
At the junction of the atria and ventricles
This is the first division of the heart; they will end up becoming the AV valves, septum intermedium, and fibrous valve skeleton.
What fills the endocardial cushions?
Initially, cardiac jelly, but later, signalling molecules cause an endothelial to mesenchyme transition and migration of mesenchyme into the cushions.
The primordial atrium is divided during development. What structures contribute to this? (traditional view)
The septum primum, and septum secundum
*Revised view: There is no septum secundum.
Distinguish between the atrial septum’s foramina primum and secundum.
The foramen primum “forms first”, it is actually the space not filled in by the septum primum. It eventually fills in, while the foramen secundum forms suprior to it and eventually contributes to the foramen ovale.
How does the foramen ovale only permit R > L shunting?
The flapper valve (the bulk of the interatrial septum) cannot flip beyond the “septum secundum” (actually the superior interatrial fold).
What congenital disorders could result from abnormal development of the septum primum?
Atrial septal defects
What tissues contribute to the partitioning of the outflow tract?
Conotruncal/bulbar ridges. Ultimately from cardiac as well as neural crest mesenchymes.