Fetal blood is returned to the umbilical arteries and the placenta through the
A. Hypogastric arteriesB. Ductusvenosus
C. Portal vein
D. Inferior vena cava
The answer is A.
Fetal blood is returned directly to the
placenta through the two hypogastric arteries. The distal portions of the
hypogastric arteries atrophy and obliterate within 3 to 4 days after birth;
remnants are called umbilical ligaments. Fetal oxygenation is aided by the
presence of three vascular shunts: the ductusvenosus, foramen ovale, and
ductusarteriosus. The ductusvenosus shunts oxygenated blood from the umbilical
vein into the inferior vena cava. The foramen ovale deflects the more oxygenated
blood from the right atrium into the left atrium, thereby bypassing pulmonary
circulation. Approximately two- thirds of the blood ejected from the right
ventricle is shunted pulmonary circulation through the ductusarteriosus.
