Ouch! Blood!

Not a happy sight! A little blood is not serious. A lot of blood can mean death. Since ancient times people have known that blood is the red liquid that comes out of wounded people and animals. Blood and life are connected. But how? Some of blood's secrets are revealed by extraordinary pictures taken with a very modern invention --the electron microscope. It magnifies things hundreds, even many thousands, of times larger than their actual size.

Oxygen, Coming Right Up

A drop of blood the size of the dot at the end of a sentence is packed with five million red blood cells. Each tiny red cell looks like a doughnut with a dent instead of a hole. Red cells are like tiny rafts floating through your body in a river of about five quarts of a straw-colored liquid called plasma.

Why red? The red pigment, called hemoglobin, contains iron. When iron combines with oxygen it turns red. So the job of hemoglobin is to combine with oxygen. Red cells pick up oxygen in the lungs. The heart pumps them through sixty thousand miles of arteries, veins, and capillaries on a round-trip journey. They deliver the life-giving oxygen to every other cell in the body. They pick up carbon dioxide, a waste gas, and return to the lungs for us to breathe it out. The red cells are now ready for another load of oxygen.

The shape of red cells gives them a larger surface area for exchanging oxygen and carbon dioxide gases. It also makes them very flexible. Red cells are often bent and squeezed as they are pushed through the tiny capillaries.


 Illustrated in full color with electron photomicrographs. Scholastic Books, 1997

Electron Microscopy Copyright© 1995, 1996, 1997, 1998 Dennis Kunkel.
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