What distinguishes veins from arteries?

Veins are distinguished from arteries primarily by their role in the circulatory system, specifically in the transport of blood back to the heart. The statement that veins return deoxygenated blood to the heart is accurate. In the systemic circulation, veins collect deoxygenated blood from the body's tissues, which is low in oxygen and rich in carbon dioxide, and transport it back to the heart. This process is crucial for maintaining proper blood circulation and facilitating the exchange of gases in the lungs, where carbon dioxide is removed and oxygen is replenished.

In contrast, arteries are responsible for carrying oxygenated blood away from the heart to various parts of the body. This oxygen-rich blood is necessary for sustaining the metabolic needs of tissues and organs. Therefore, the primary distinction between veins and arteries lies in their function: veins return blood to the heart, while arteries transport blood away from it. This functional difference highlights the integral roles each type of vessel plays in the overall circulatory system.