You know what blood is — it’s the stuff that oozes out if you get a paper cut. The average person has about 1 to 1½ gallons (4-6 liters) of it. But what is blood, really, and where does it come from?
Your body’s cells need a constant supply of food, oxygen, and other essentials, as well as prompt removal of wastes, to stay alive. Blood provides this delivery and disposal service as it flows around the body. Billions of oxygen-carrying red blood cells give blood its red color. Blood also contains white blood cells that defend your body against invading pathogens or germs.
The average adult has about 10 pints or 5.7 liters of blood, but a newborn baby has only a cupful. Blood has the amazing ability to turn from liquid to solid in minutes and so help mend cuts in your skin. A plaster can help a cut to heal by closing the skin and keeping out dirt. Plasters also stop you from scratching, which can make a cut worse.
There are four main types of blood, called blood groups.
A, O, AB, B.
Now that you know how important blood is, what can you do? Kids generally aren’t allowed to donate blood, but when you’re older consider giving the gift of life!