After birth, the infant's ductus venosus constricts because:
A)more blood is returning from the lungs
B)the umbilical arteries have been cut
C)more blood is flowing to the lungs
D)the umbilical vein has been cut

Question

Quizplus · Accepted Answer

The ductus venosus is a fetal blood vessel that connects the umbilical vein to the inferior vena cava, allowing most of the oxygenated blood from the placenta to bypass the liver and flow directly to the heart. After birth, the umbilical cord is cut and the umbilical vein collapses, which causes a decrease in blood flow through the ductus venosus. As a result, the ductus venosus constricts and eventually becomes a fibrous cord (ligamentum venosum) within a few weeks after birth.

After Birth, the Infant's Ductus Venosus Constricts Because