Subscribe Now! National Geographic Magazine $15
Visit our Online Shops

Sign up for free

Newsletters

Once a month
get new photos
and expert tips.

Heart Quiz

The multimedia content of this page is loading. If it does not appear shortly, you may need to enable JavaScript in your Web browser and/or get the latest Flash Player plug-in to view it.

More About the Heart

Related Features

Photo: A brain with measuring tape

Quiz: Brain

Are you a brain when it comes to the brain? Find out with this quiz and give your gray matter a workout in the process.

Photo: Enlarged view of a female Anopheles mosquito

Article: Malaria—Bedlam in the Blood

Nearly half a billion people get malaria worldwide each year. More than a million die. After decades of neglect, the world is renewing its fight against the disease.

Photo: Stem cell patient

Article: The Stem Cell Divide

Embryonic stem cells may someday help doctors treat ills ranging from paralysis to diabetes. But science must contend with politics before that hope can be realized.

Photo: Testing a Thai farmer's ducks for bird flu

Article: Tracking the Next Killer Flu

In Southeast Asia a virus that kills chickens is now also killing people. And in those deaths, public health experts hear the distant rumbling of a global catastrophe.

Health and Human Body Topics

SPECIAL ADVERTISING SECTION

Photo: Hot spring in Ethiopia's Danakil Depression

Pathways to a Greener World

Join the climate conversation.

2008 Grand Prize Winner

Photo Gallery

See who won this year’s grand prize trip to the Grand Canyon!

Body: The Complete Human

Image: Cover of Body: The Complete Human book

Explore the human machine.

The Incredible Human Body DVD and Video

Image: Cover of the Incredible Human Body video and DVD

Explore the human body from the inside out.