Final answer:
In systemic circulation, the red vessels are arteries that carry oxygen-rich blood from the heart to the body's tissues. The major systemic artery is the aorta.
Step-by-step explanation:
In systemic circulation, the red vessels, which are depicted as red in models and images to indicate the oxygen-rich status of the blood they carry, are called arteries. Specifically, the systemic arteries transport blood that is rich in oxygen from the heart throughout the body to supply the organs and tissues. Once the oxygen has been delivered and the blood has become oxygen-poor, it returns to the heart through the systemic veins, often represented in blue on the same models and diagrams.
The largest artery in systemic circulation is the aorta, which carries oxygenated blood from the left ventricle of the heart to the body. After the oxygen exchange at the tissue level, the deoxygenated blood collects into veins, which lead back to the heart via the superior and inferior venae cavae, completing the systemic circuit.