Fetal Circulation

Placenta

• organ of gas exchange

Single umbilical vein

• oxygen rich blood is carried from the placenta to the fetal heart, through a single umbilical vein

Umbilical cord

• houses the single umbilical vein

• contains two umbilical arteries

Umbilical vein

• blood in the umbilical vein is rich in oxygen from the placenta and is returned to the heart

Ductus venosus

• continous to connect with the inferior vena cava which empties into the RA

Atrial septum

• Once blood is in the RA, the blood is immediately sent through an opening In the atrial septum

Foramen oval

• Allows blood to avoid going to the non-functional lungs via the RV

• serves as a bypass of the RV

• closes at the moment of birth when thoracic pressure changes

Ductus arteriosus

• A connection between the pulmonary trunk and the aorta

• this would prevent the blood from traveling to the fetal lungs

• allows blood to enter the aorta and be distributed throughout the body

• closes down throughout development

Ligamentum arteriosum

• when the ductus arteriosus closes down it becomes the Ligamentum arteriosum

Fossa ovalis

• a shallow depression between the right and left atria

• once the foramen ovale closes it become the fossa ovalis

Fetal circulation pathway

• placenta »»» Umbilical cord »»» Ductus venosus »»» Inferior Vena Cava »»» Right Atrium »»» Foramen Ovale »»»Left Atrium »»» Left Ventricle »»» Aorta »»» Systemic arteries »»» Umbilical arteries »»» Placenta

Alternative pathway of fetal circulation

• Placenta »»» Umbilical vein »»» Ductus Venosus »»» Inferior Vena Cava »»» Right Atrium »»» Right Ventricle »»» Pulmonary trunk »»» Ductus Arteriosus »»» Aorta »»» Systemic system »»» Umbilical arteries »»» Placenta

Ductus arteriosus becomes….

• ligamentum arteriosum

Foramen Ovale becomes…

• Fossa Ovalis

Ductus Venosus becomes….

• Ligamentum venosum

Umbilical vein becomes…

• Ligamentum teres

Umbilical arteries become….

• Medial umbilical ligaments