Circulatory System Fetal Circulation

•  Modified to allow baby to develop in mother’s uterus

•  Fetus does not use its own pulmonary circuit and lungs until birth

•  Oxygen is transported from mother to fetus via placenta

Fetal Circulation 1.  Umbilical Cord Veins

•  Sends oxygen-rich blood & nutrients to the ductus venosus (in liver) from placenta

2.  Ductus Venosus (Venous Duct) •  Takes oxygen-rich blood through liver (acts as

bypass) •  Harmful substances can be passed onto the fetus

from mom. 3.  Foramen Ovale (Oval Opening)

•  Opening between two atrium •  oxygen-rich blood from mom is shunted from RA to

LA bypassing the lungs •  Gap closes following the umbilical cord being cut.

Fetal Circulation 4. Ductus Arteriosus (Arterial Duct)

•  Connection between pulmonary artery and aorta •  Directs blood away from lungs into systemic

circulation •  After birth, cells cause opening to close.

5. Umbilical Arteries •  Takes blood (low in oxygen) from infant to

mother for exchange (back through umbilical cord)