Embryology

[SaintJude]

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Which of the following statements is false?
A) In fetal circulation, blood is oxygenated in the placenta.
B) A small amount of blood reaches the fetal lungs.
C) Are birth, the blood pressure in the right atrium decreases.
D) In fetal circulation, the blood delivered via the aorta has a higher partial pressure of oxygen than the blood that was delivered to the lungs.


How can I make sense of pressure changes in the fetal heart at birth and during gestational period?

Answer is -highlight -->: D.

 

[wish2bMD]

Prior to birth, a fetus' lung does not function. Therefore, instead of blood->lungs from the right atrium, the blood is diverted to the left atrium from the right atrium (foramen ovale) or from the pulmonary artery to the aorta (ductus arterosus). A small amount of blood that reaches the fetal lungs would therefore be the same in composition to the blood delivered via the aorta.

 

[MedPR]

Prior to birth, a fetus' lung does not function. Therefore, instead of blood->lungs from the right atrium, the blood is diverted to the left atrium from the right atrium (foramen ovale) or to the left ventricle from the right ventricle (ductus arterosus). A small amount of blood that reaches the fetal lungs would therefore be the same in composition to the blood delivered via the aorta.

I'm pretty sure the ductus arteriosus is what is relevent here. It connects the aortic arch and the pulmonary artery. So blood that typically would be pumped to the lung via the pulmonary artery is pumped directly into systemic circulation instead.