Heart embryology Flashcards
During which week does the septum begin to form?
End of week 4
What week is the heartbeat established?
4th
What process forms the folds that will become the heart?
Cephalocaudal folding
What primitive germ layer forms the heart wall layers?
Mesoderm
H
U
What are the five dilations that develop in the heart tube?
Truncus arteriosus, bulbus cordis, primitive left ventricle, primitive atrium, left and right horns of sinus venosus
During primitive circulation, where does the blood enter and leave the heart tube, respectively?
Enters- sinus venosus
Leaves- truncus arteriosus
When does the heart tube begin to loop and when should it be complete?
End of week 3, end of week 4
What part of the heart tube will become the right ventricle?
Bulbus cordis
What will the sinus venosus horns form?
Smooth wall of the atria
What part of the heart tube will form the muscular walls of the atria?
Primitive atrium
What will the truncus arteriosus form?
VOT (aorta and pulmonary trunk)
What separates the primitive heart before the septum forms?
The atrioventricular sulcus separates the atrium and the ventricles.
The interventricular sulcus separates the ventricle and the bulbus cordis.
In which direction does the septum primum grow?
Posterior to anterior
What is the function of the foramen (ostium) primum?
A hole between the left and right atria so that blood can bypass the lungs in a developing foetus
What does the septum intermedium separate?
The atria from the ventricles
How does the foramen primum close?
The posterior and anterior endocardial cushions, that form the septum intermedium, joins with the septum primum, closing the hole.
Where does the foramen secundum open and how?
Superior edge of the septum primum, cell apoptosis destroys the cells there creating a new opening.
Which primitive septal wall does the foramen ovale arise from and how?
Septum secundum, this grows to the right of the septum primum and does not fuse with the septum intermedium, leaving the foramen ovale which will persist until birth.
Where is the foramen ovale located?
Near the base of the right atrium
What will act as the valve to close the foramen ovale at birth?
The septum primum
What weeks do the AV valves form?
5-8
During which weeks does the truncus arteriosus undergo septation?
7-8
What divides the truncus arteriosus?
Conotruncal ridges
Describe the process that forms the semilunar valves
The truncus arteriosus swells and connects to the right and left ventricles helically (spirally)
How many aortic arches are there in the primitive circulation?
6
Which pharyngeal arch arteries are important to remember?
3rd- forms common and internal carotids
4th- forms right subclavian and part of aortic arch
6th- forms ductus arteriosus
What should the ductus arteriosus become after birth?
Ligamentum arteriosum
What does the degeneration of the ductus arteriosus allow passage of?
Left recurrent laryngeal nerve
What is the importance of the ductus venosus before birth?
Bypass the liver and deliver oxygenated blood from the placenta straight into the IVC
What are the four identifying features of the tetralogy of fallot?
Pulmonary stenosis, VSD, overriding aorta and right ventricular hypertrophy
