Final answer:
Blood travels from the fetus through the umbilical arteries to the placenta to deliver wastes, including carbon dioxide, before receiving oxygen and nutrients in return.
Step-by-step explanation:
Some of the blood in the Aorta returns to the placenta through the 2 umbilical arteries to deliver wastes and carbon dioxide from the fetus to the mother for disposal.
The descending aorta transports a mixture of oxygenated and deoxygenated blood to the lower body and branches out into the two umbilical arteries. These arteries carry blood that is low in oxygen and high in carbon dioxide and fetal wastes back to the placenta.
Here, an exchange occurs: fetal wastes and carbon dioxide diffuse into the maternal circulation, while oxygen and nutrients from the mother cross into the fetal blood. This circulation is crucial as the fetal lungs are not yet functional for gas exchange, and the placenta fulfills the roles of the lungs, kidneys, and digestive system.