Final answer:
The statement regarding the superior and inferior vena cava carrying oxygen-poor blood to the heart is true, as they are part of the systemic circuit returning deoxygenated blood to the heart.
Step-by-step explanation:
The statement that 'oxygen-poor blood enters the heart through two veins: the superior vena cava and the inferior vena cava' is true. The superior vena cava carries deoxygenated blood from the upper parts of the body while the inferior vena cava carries it from the lower parts, both emptying into the right atrium of the heart. This is part of the systemic circuit, where blood that has circulated through the body and has had its oxygen used up, returns to the heart to be sent to the lungs to be reoxygenated.
The pulmonary circuit is then involved, where the newly oxygenated blood is transported back to the heart via the pulmonary veins, which goes against the typical pattern since these veins carry oxygen-rich blood. It is important to note, for clarity, that the statement in your question about the pulmonary artery is correct; it carries deoxygenated blood from the heart to the lungs.