What is a "blood vessel"?

A blood vessel refers to any of the tubular structures in the human body that carry blood, including arteries, veins, and capillaries. Arteries carry oxygenated blood away from the heart, while veins return deoxygenated blood back to the heart. Capillaries are the smallest blood vessels and facilitate the exchange of oxygen, nutrients, and waste products between the blood and surrounding tissues. Together, these blood vessels form a complex network that enables the circulation of blood and the delivery of essential substances to various parts of the body.