Through which vessel is oxygenated blood returned to the heart from the lungs?

Oxygenated blood is returned to the heart from the lungs through the pulmonary veins. These specialized vessels carry oxygen-rich blood from the alveoli, where gas exchange occurs, directly to the left atrium of the heart. This is a critical part of the circulatory process, as it allows the heart to pump this oxygenated blood throughout the body.

In the context of the cardiovascular system, arteries typically carry oxygenated blood away from the heart to the body's tissues, while veins are responsible for returning deoxygenated blood to the heart. Capillaries serve as the exchange sites where oxygen and carbon dioxide are transferred between the blood and tissues but do not serve to return blood to the heart. The pulmonary veins are unique as they specifically transport oxygen-rich blood from the lungs back to the heart, highlighting their essential role in the pulmonary circuit of the circulatory system.