In the late-gestation fetus, approximately what proportion of the combined ventricular output is directed to the placenta through the umbilical arteries?
- A About 10 percent
- B About 25 percent
- C About 40 to 50 percent ✓
- D About 70 percent
Correct answer: C. About 40 to 50 percent
Explanation
The placenta is the fetal gas-exchange organ and receives roughly 40 to 50 percent of combined ventricular output, returning via the single umbilical vein. Because the fetal lungs receive only about 10 to 15 percent of the output, pulmonary vascular resistance remains high in utero. This large placental share collapses abruptly at birth when the cord is clamped, raising systemic resistance.
Reference: Ganong's Review of Medical Physiology, 26th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.