The fetus receives all its nutrients and oxygen through the placenta. Therefore, fetal lungs are non-functional, as far as pulmonary circulation is concerned. It only needs to receive enough blood to sustain growth. There are a couple of features in the fetal cardiovascular system to shunt the blood away from the lungs and only provide enough for sustenance and keep most blood in general circulation. Which two structures in fetal circulation aid in bypassing the pulmonary circulation