Geoffrey Henry, age 13, of Lynn, Mass., for his question:
WHAT DOES BLOOD PLASMA DO?
Blood plasma is the straw colored liquid part of the blood that carries dissolved food materials to all parts of the body. It is the part of blood that remains after the red and white blood cells are removed.
Plasma also picks up waste materials, produced by the body cells, and carries them to the organs that remove wastes from the body. In addition, plasma also carries secretions from certain glands in the body.
Plasma contains water, salts, proteins and other materials.
One of the proteins found in plasma is called fibrinogen. It is this substance that keeps you from bleeding to death from the slightest cut. Fibrinogen makes it possible for the blood to clot to seal off the wound.
Another protein in the plasma is called globulin. This protein carries disease fighting substances known as antibodies that destroy germs in the body.
And a third important protein in plasma is called albumin. This substance helps to keep the blood volume and blood pressure normal.
It was found in the 1930s that plasma could be separated from whole blood. Plasma is obtained by separating out the blood cells in a machine called a centrifuge. The liquid plasma can be kept for much longer than whole blood. It can also be frozen or dried, and in these forms it can be kept indefinitely.
Plasma is used for blood transfusions when whole blood is not needed or cannot be obtained. It is also used to restore blood volume lost during severe bleeding.
Plasma has saved the lives of millions of soldiers injured in battle and persons injured in accidents. Plasma is also often used during operations to combat the condition known as shock.
In certain diseases, the body is literally starved for a certain protein. Scientists have learned to produce such substances from plasma and from other materials.
Scientists have attempted to find safe substitutes for plasma, but substitutes are not as effective as whole blood or plasma. Most antibodies are concentrated in the portion of the blood's globulin protein called gamma globulin. Doctors use gamma globulin to help prevent infectious jaundice, measles and other diseases. Bomb like containers are used to freeze a plasma and alcohol mixture at minus 70 degrees centigrade. This process is the final step in producing gamma globulin.