Final answer:
The umbilical cord contains two arteries that carry deoxygenated blood from the fetus to the placenta and a single vein that carries oxygenated blood from the placenta to the fetus.
Step-by-step explanation:
The umbilical cord is a critical part of fetal circulation, connecting the fetus to the placenta. This cord includes two umbilical arteries and a single umbilical vein. The two umbilical arteries carry deoxygenated blood and waste products from the fetus to the placenta, where exchange with the mother's oxygenated blood takes place. In contrast, the single umbilical vein carries oxygen-rich and nutrient-rich blood from the placenta back to the fetus, which is crucial for fetal development and growth.
After birth, the umbilical cord is clamped and cut, and the remnants of the umbilical vessels eventually form ligaments. These ligaments are the only traces left in the adult body as evidence of the once vital umbilical arteries and vein. Therefore, the umbilical cord carries blood away from the baby via the arteries and carries oxygen to the baby via the umbilical vein, and does not usually separate from the placenta until after birth when it's no longer required.