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From your feet to your brain and all points in between, your heart has a tough job circulating blood all through your body. It’s easy to imagine how blood flows to your feet. It goes down hill. Gravity pulls everything down, including your blood. The only way blood gets up from your feet or out to your hands is from the pumping of your heart. And it works hard. Just try lifting a bucket of water sometime. It’s heavy, and so is your blood. Your heart has to pump your blood all day, every day.

See how hard your HEART has to work!

What You Need

  1. your hands

What You Do

  1. Hold one hand straight up over your head, and let the other one hang down at your side.
  2. Slowly count to sixty.
  3. Now hold your hands side by side and look them over.

What's Happening?

See how the hand that was up in the air is much paler than the one that was hanging down? That’s because gravity made it harder for your heart to pump blood to the hand over your head, but it helped your heart to pump blood to the hand that was hanging down. The more blood, the darker your hand. Blood flowing can get science going!

Bill Nye