Anatomy and Physiology II Practice Test

Which two structures in a developing fetus allow blood to bypass the lungs?

1. Foramen Ovale and Ductus arteriosus

2. Umbilical vein and artery

3. Coronary artery and vein

4. Septum primum and secundum

The correct answer is: Foramen Ovale and Ductus arteriosus

In a developing fetus, the lungs are not used for gas exchange as they are in postnatal life; instead, oxygenated blood is delivered from the mother via the placenta. To accommodate this unique situation, certain structures exist that allow blood to bypass the non-functioning lungs. The foramen ovale is an opening between the right and left atria, permitting blood to flow directly from the right atrium to the left atrium. This allows oxygen-rich blood from the placenta to bypass the right ventricle and the pulmonary artery, consequently avoiding the lungs. The ductus arteriosus is a vessel connecting the pulmonary artery to the aorta. This shunt allows any blood that does enter the pulmonary artery (which is minimal) to be redirected into the aorta rather than going into the lungs. Together, these two structures— the foramen ovale and the ductus arteriosus— are crucial for ensuring that the developing fetus receives oxygenated blood efficiently while avoiding the lungs, which are not yet functional in gas exchange. Thus, they play a fundamental role in fetal circulation, making this combination the correct answer. The other options do not serve the same function. The umbilical vein and artery are involved in transporting