What happens to the blood traveling through the ductus venosus?

• A. It goes directly to the lungs
• B. It enters the aorta
• C. It bypasses the liver
• D. It stays in the umbilical vein

Answer: (C)

The blood traveling through the ductus venosus is crucial for fetal circulation as it serves an important role in bypassing the liver. In fetal life, oxygen-rich blood from the placenta enters the fetus via the umbilical vein. The ductus venosus is a vessel that allows this blood to flow directly into the inferior vena cava, thereby significantly reducing the amount of blood that would otherwise need to be processed by the liver. This is particularly important because the fetal liver is not fully developed for its metabolic functions, and most of the oxygenated blood is instead directed to the heart and then to the rest of the body, especially the brain.

The other options do not accurately represent the physiological role of the ductus venosus. Blood does not go directly to the lungs, as extrauterine oxygenation occurs in the lungs after birth, nor does it directly enter the aorta since it first flows into the inferior vena cava. Additionally, it does not stay in the umbilical vein because that vein is specifically for delivering blood to the fetus rather than containing blood.