Final answer:
The placenta is the organ that connects the mother's blood supply with the fetus, facilitated by the umbilical cord, which contains two arteries and one vein for nutrient and gas exchange.
Step-by-step explanation:
The organ that connects the mother's blood supply to that of the fetus is called the placenta. This structure is critical for pregnancy, acting as a lifeline that facilitates the exchange of nutrients, gases, and wastes between the mother and fetus. The fetus is linked to the placenta by the umbilical cord, which is composed of two arteries and one vein. Oxygen and nutrients move from the mother's bloodstream to the fetus through this connection, while carbon dioxide and waste products are transferred from the fetal blood to the mother's bloodstream via the placenta.
The umbilical cord is effectively a tube containing two umbilical arteries and one umbilical vein. The arteries carry deoxygenated blood and waste from the fetus to the placenta, whereas the umbilical vein supplies oxygenated, nutrient-rich blood from the placenta to the fetus, sustaining the developing child's growth and health throughout pregnancy.