Circulatory System of Foetus

Fetal lungs are non-functional > placenta is used instead

Umbilical vein carries oxygenated blood from placenta to vena cava

Blood in the heart bypasses through foramen ovale

Oxygenated blood flows from right into left atria / flap valve prevents back flow of blood

Some blood in right atria passes to right ventricle into pulmonary artery (to lungs)

Blood bypasses lungs through ductus arteriosus

Oxygenated blood flows from pulmonary artery into aorta

Umbilical arteries carry deoxygenated blood from aorta to placenta