What are the blood vessels that carry oxygenated blood from the heart to the tissues?

• A. Arteries
• B. Veins
• C. Capillaries
• D. Venules

Answer: (A)

Oxygenated blood travels from the heart into the systemic arteries. These vessels are thick-walled and muscular to withstand the high pressure of ventricular contraction and to propel blood outward toward every tissue. As arteries branch into smaller arteries and arterioles, they eventually feed capillaries where oxygen and nutrients diffuse into cells. Veins and venules then return the blood to the heart after it has delivered its oxygen. Capillaries are the actual exchange sites. It’s helpful to remember a special case in the pulmonary circuit: the pulmonary artery carries blood to the lungs and is deoxygenated, while the pulmonary veins return oxygenated blood to the heart. But when talking about delivering oxygen-rich blood to tissues, the vessels doing the job are the arteries.