How many blood vessels are found in the umbilical cord?
Since the lungs and digestive system are not yet functioning in a fetus, all nutrient, excretory, and gas exchange occur through the placenta. Nutrients and oxygen move from the mother’s blood into the fetal blood, and fetal wastes move in the opposite direction. The umbilical cord contains three blood vessels: one large umbilical vein and two smaller umbilical arteries. The umbilical vein carries blood rich in nutrients and oxygen to the fetus. The umbilical arteries carry carbon dioxide and debris-laden blood from the fetus to the placenta. As blood flows superiorly toward the heart of the fetus, most of it bypasses the immature liver through the ductus venosus and enters the inferior vena cava, which carries the blood to the right atrium of the heart. Since fetal lungs are nonfunctional and collapsed, two shunts see to it that they are almost entirely bypassed. Some of the blood entering the right atrium is shunted directly to the left atrium through the foramen ovale, a flap-like o
