Monica Crisp, age 9, of Gastonia, N.C., for her question:.

WHAT IS PLASMA?

Blood isn't the uniform red fluid it seems to be. It is actually a very complex mixture of a number of different types of cells suspended in a liquid. The cells are both red and white corpuscles and platelets while the liquid in which they are suspended is called plasma.

Blood plasma makes up about 55 percent of the total volume of the blood.

Blood plasma is often extracted from whole blood and held for later transfusions. Plasma contains all the ingredients in the complex blood mixture except the cells. The advantages of using plasma over whole blood is that plasma can be frozen or dried and stored for several months before use. Also, since it contains no red cells, there's no danger of mismatching.