Flashcards in CVS Session 3 (Lecture 3.1) Deck (17):
Which 3 septa are created during septation?
3) Ventricular outflow tracts separating aorta and pulmonary trunk
After looping, by what structure does the atrium communicate with the ventricle?
Describe the first step of septation.
Expansions in the dorsal and ventral walls cause the production of endocardial cushions in the AV region.
They divide the heart into right and left channels.
Describe atrial septation (4 steps).
1) Septum primum grows down towards the fused endocardial cushions
2) Ostium primum is the hole present before septum primum fuses with the endocardial cushions
3) Before the O.P. closes, a second hole, the ostium secundum appears in septum primum
4) A second crescent shaped septum, the septum secundum grows; the hole in the septum secundum is the foramen ovale.
Where are the left and right auricles derived from?
What does the RA absorb?
What does the LA sprout and absorb?
Sprouts PV, grows and absorbs it + first 4 branches
What is the adult remnant of the shunt used to bypass the lungs?
Fossa ovalis (from foramen ovale) in RA
What are the two components of the ventricular septum?
Muscular and membranous
Describe ventricular septation.
1) Muscular portion forms most of the septum and grows upwards towards the fused endocardial cushions.
What is the name of the small gap left by the upward growth of the muscular portion of the ventricular septum?
Primary interventricular foramen.
How is the PIF closed?
Membranous portion of the interventricular septum formed by CT derived from endocardial cushions.
How is the outflow tract separated?
Endocardial cushions appear in the TA and grow and twist around each other forming a spiral septum - conotruncal septum
What happens when the fetus takes its first breath in regards to circulation?
1) Respiration begins
2) LA pressure increases so foramen ovale closes as it increases above RA pressure (RA
3) DA contracts
4) After birth DV closes with placental support removed.
Why does the foramen ovale close?
What do the foramen ovale, ductus arteriosus, ductus venosus and umbilical vein turn into in the adult?
1) FO >>> Fossa ovalis
2) DA >>> Ligamentum arteriosum
3) DV >>> Ligamentum venosum
4) Umbilical vein >>> Ligamentum teres (hepatis)