Body Systems

Your body is pretty amazing. At any given point you have many biological processes going on -- circulatory, digestive, brain & central nervous systems and more. Learn about these body systems as well as the eye, ears, nose and throat.

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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