MCAT Question A Day - 6/11/13 - Answer!
Which blood vessels carry blood with a relatively high oxygen concentration?
A. All arteries
B. All arteries and the pulmonary veins
C. Pulmonary veins and all arteries except the pulmonary arteries
D. Pulmonary arteries and pulmonary veins
The correct answer is (C). The pulmonary arteries bring blood (low in oxygen and high in carbon dioxide) that has returned from the body’s tissues to the lungs. They are the only arteries that are relatively oxygen-poor. In contrast, the pulmonary veins bring freshly oxygenated blood from the lungs back to the heart, and are the only veins that are relatively oxygen-rich.
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