This color-enhanced image was made with an electron microscope, so the objects it depicts are extremely small. Do you know what they are? This incredible photo shows red blood cells leaking out of a ruptured blood vessel.
Blood vessels are part of the circulatory system, the “highway” system of the human body that transports materials to all of its cells. Red blood cells carry some of these materials, so they are a little like trucks on a highway. In this chapter, you will learn more about capillaries, red blood cells, and other structures of the circulatory system.