Which structures are primarily involved in returning blood to the heart from the periphery?

The primary structures involved in returning blood to the heart from the periphery are the superior and inferior venae cavae. These large veins collect deoxygenated blood from various parts of the body and channel it back to the right atrium of the heart. The superior vena cava is responsible for draining blood from the upper part of the body, including the head, neck, and arms, while the inferior vena cava collects blood from the lower body, including the abdomen and legs.

This return mechanism is critical for maintaining proper circulation, ensuring that blood can be reoxygenated in the lungs and then pumped back out to supply the body's tissues. In contrast, the aorta and carotid arteries are involved in distributing oxygenated blood from the heart to the periphery, which is not their primary function. The pulmonary arteries and veins are responsible for transporting blood between the heart and lungs for gas exchange. Cerebral arteries carry oxygen-rich blood to the brain, but they do not play a role in returning blood to the heart.