Cardiovascular: Pathology

Question 1

When the heart is first developing, a tissue called the ______ ______ between the left and right atria grows downward, slowly creating two separate chambers by closing this gap, or ostium primum, which means “first opening.” The septum primum then fuses with the ____________ _______ and closes the gap completely. Meanwhile, a hole appears in the upper area, called the ostium secundum, or “second opening.”

Answer 1

septum primum
endocardial cushion

[From Osmosis video, “Atrial septal defect”]

Question 2

Now, we also have the septum secundum which grows downward, just to the right of the septum primum, and covers the ostium secundum like a curtain, leaving a small opening called the _______ _____, thus essentially creating a makeshift valve that allows blood to go from right atrium to left atrium, but not the other way.

Answer 2

foramen ovale

[From Osmosis video, “Atrial septal defect”]