Final answer:
The pulmonary veins are the vessels that return oxygen-rich blood to the heart from the lungs after gas exchange. The systemic circuit involves arteries supplying oxygenated blood to the body and veins that return deoxygenated blood to the heart, which is then sent to the lungs via the pulmonary arteries for reoxygenation.
Step-by-step explanation:
The vessels that return blood to the heart full of oxygen are known as the pulmonary veins. The pulmonary veins transport oxygen-rich blood from the lungs back to the heart after it has gone through the gas exchange process. In contrast, the superior and inferior vena cava are vessels that carry oxygen-poor blood from the body back to the heart.
In the cardiovascular system, there are two main circuits: the systemic circuit and the pulmonary circuit. The systemic arteries carry oxygenated blood from the heart to the rest of the body, while the systemic veins return deoxygenated blood to the heart. The pulmonary circuit, on the other hand, is responsible for refreshing the blood with oxygen. The pulmonary arteries carry deoxygenated blood from the heart to the lungs, and the pulmonary veins complete the circuit by bringing oxygenated blood back to the heart.