Fetal Circulation - Heart Dissection (L2)

Question 1

Placenta

Answer 1

The site for gas exchange in the fetus. Fetal blood gives up CO2 and picks up O2.

Question 2

Foramen ovale

Answer 2

A hole in the wall between the right and left atriums, covered by 2 membranes that form a one-way valve.

Because of the large resistance to flow in the pulmonary circuit caused by the fetus’s collapsed lungs, pressure on the right side of the heart is higher than on the left. This allows the valve to open, allowing blood to flow directly from the right atrium to the left, and then out the systemic circuit.

Question 3

Ductus arteriosis

Answer 3

A tube connecting the pulmonary artery with the aorta. The small amount of blood that makes it to the right ventricle in the fetus gets pumped out through the pulmonary artery and would flow through the pulmonary circuit, except a large portion gets shunted through this tube.

This will atropy from disuse, will be seen in adult as tough ligaments.