Blood and Circulation

Your blood is your bud. Without blood, your skin would dry up and fall off, your internal organs would die, and your brain would be kaput. Blood gives every cell in your body the food and oxygen it needs to survive. Blood also cleans up after our cells by carrying away waste. Blood even protects your body from disease. What more could you ask from a friend?

Blood patrols your entire body. Blood is pushed around by a powerful pump called the heart. Every time your heart lub-dubs, blood is propelled through tubes called arteries, capillaries, and veins. Your heat pushes your blood in a complete loop around your body about 2,000 times every day.

Your heart is a muscle, and, like all muscles, it can get stronger. A healthy heart needs exercise to stay strong. An average heart pumps about 70 times a minute, but a healthy, well-exercised heart pumps 50 or 60 times a minute. Healthy hearts don’t have to work as hard to move your blood around. Now that’s pumped up!

Be sure to watch the “Blood and Circulation” episode, because Bill Nye really takes science to heart.

The Big Ideas

• To stay alive, our bodies use blood to carry our food, oxygen, and waste
• Our hearts pump blood through arteries, veins, and capillaries all through our bodies
• The heart is a muscle, which can be made stronger through exercise.

Did You Know That?

• There are four main types of blood – A, B, AB, and O?
• Some capillaries are 50 times thinner than a baby’s hair?
• If you put all of your blood vessels in a line, they would stretch around the Earth’s equator 2 1/2 times?

Books of Science!

• “Blood” by Anna Sanderman. Published by Copper Beech Books, 1996