Where are unoxygenated blood and oxygenated blood found?

Unoxygenated blood is primarily found in the veins, returning from the body's tissues to the heart, specifically entering the right atrium. From there, it is pumped to the lungs via the pulmonary arteries for oxygenation. Oxygenated blood, on the other hand, is found in the pulmonary veins as it returns from the lungs to the left atrium of the heart, and then it is distributed throughout the body via the aorta and systemic arteries.