What lives about three months and travels over a million
miles before it dies? A red blood cell does—and there are
trillions of them speeding around inside your body right
now!
Red blood cells are an important part of your blood.
One main job of blood is to deliver oxygen to all parts of the
body. Red blood cells are the blood's oxygen carriers.
They pick up oxygen from your lungs and deliver it where it
is needed.
Dropping Off Oxygen
When you inhale, or breathe in, oxygen enters your lungs.
Red blood cells pick it up and carry it through blood
vessels to your heart. Then your heart pumps the oxygenrich blood through blood vessels to all of your cells.
Oxygen allows your cells to get energy from the food you eat.
When your cells use oxygen, they make carbon dioxide.
Carbon dioxide isn't good for cells—it is a waste that has to
be removed. Removing wastes is another job of the blood.
Picking Up Carbon Dioxide
After your blood gathers up the carbon dioxide from cells,
the blood moves back to your lungs. Now the blood can drop
off the carbon dioxide. When you exhale, or breathe out,
carbon dioxide is pushed out of your body.
In your lungs, red blood cells are already picking up oxygen
for the next delivery. There's no time for a break because
cells constantly need oxygen to live. Your blood makes a
Discovery Education Science
© 2007 Discovery Communications, LLC
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Your Amazing Blood
complete trip around the body about once a minute—that's
about 1,440 times each day!
What Is Blood?
Blood is a fluid that contains many living cells. Red blood
cells carry oxygen and give blood its red color. In a drop of
blood, there may be more than a million red blood cells!
Your blood also contains cells that fight germs and help you
heal. The liquid part of blood carries cells, nutrients, wastes,
and other materials that carry out different jobs.
Blood for Life
Your blood has many important functions. It delivers oxygen
to your cells from the air you breathe. It delivers nutrients
from the food you eat. And it removes wastes from cells.
Blood helps you fight illness and stay healthy. It even helps
keep your body at the right temperature. No wonder your
blood is always on the move. It has plenty of work to do to
keep you alive!
Discovery Education Science
© 2007 Discovery Communications, LLC
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