What is the primary function of the vena cava?

The primary function of the vena cava is to return blood from the body to the heart. The vena cava consists of two large veins—the superior vena cava and the inferior vena cava—which collect deoxygenated blood from the systemic circulation and transport it back to the right atrium of the heart. This process is essential for maintaining effective circulation and allowing the heart to pump the blood to the lungs for oxygenation.

In contrast, supplying blood to the lungs is the role of the pulmonary arteries, not the vena cava. The carrying of oxygen-rich blood to the body is performed by the aorta and its branches. Distributing hormones throughout the body is primarily the function of the endocrine system, involving various glands and the bloodstream, but is not directly related to the role of the vena cava.