Which structure is responsible for nutrient and gas exchange in the fetus?

The placenta is the organ responsible for nutrient and gas exchange between the mother and the fetus. It acts as a critical interface where maternal blood supplies oxygen and nutrients that the developing fetus needs for growth and development. Simultaneously, the placenta facilitates the removal of carbon dioxide and metabolic waste products from the fetal blood back to the maternal circulation.

This organ contains specialized structures such as chorionic villi, which increase the surface area for efficient exchange. The high vascularization of the placenta ensures that there is an adequate supply of blood flow, allowing for the effective transfer of oxygen and nutrients to the fetus.

The foramen ovale, ductus arteriosus, and amniotic sac have different roles. The foramen ovale is a shunt in the fetal heart that allows blood to bypass the lungs, which are not used before birth. The ductus arteriosus is a blood vessel that connects the pulmonary artery to the aorta, allowing fetal blood to bypass the non-functioning lungs as well. The amniotic sac, meanwhile, provides a protective environment for the fetus and cushions it within the amniotic fluid; it does not participate in the exchange of gases or nutrients. Thus, the placenta is the key structure for these essential functions