IMAT 2020 Q33 [Heart & Hole in the Septum]

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The heart of a developing human fetus normally has a hole in the septum. The septum separates the right atrium and the left atrium.

Which one of the statements about the circulation in the developing fetus with a hole in the septum is correct?

A. Blood entering the right atrium can bypass the lungs and go to the rest of the body.

B. Blood in the right atrium may return directly to the vena cava.

C. The atrioventricular node will not cause ventricular systole.

D. Blood in the pulmonary artery will go directly to the aorta.

E. The maximum pressure in the aorta is the same as the maximum pressure in the contracting atrium.

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The answer is A
as we know the blood passes through the following pathway : vena cava (superior and inferior) → right atrium → right ventricle → pulmonary arteries → pulmonary veins → left atrium → left ventricle → Aorta.
As there is a hole in the septum which separates the left and right atrium, the blood entering the right atrium can enter the left atrium and then to the left ventricle and aorta which takes it to the rest of the body.