Human Body

The human body is an amazing structure made up of many fascinating parts and systems. Learn about the human body and how its systems work together.

Learn More / Page 10

The heart is a vital organ that basically serves as a pump. Learn about heart chambers and valves, blood flow, the heart's electrical system and blood supply. Read more about how this amazing organ works.

By Carl Bianco, M.D.

There are millions of bacteria, microbes, viruses, toxins and parasites that want to invade your body. And they'd happily do it, too -- if it weren't for your immune system.

By Marshall Brain