White Cells
There are several types of 
white blood cells (WBCs) which
are sometimes collectively called leukocytes, although some
authorities reserve that term to identify only the granulocytes.
White cells are irregular in shape and size, but generally are
larger than the red cells. They differ from the red cells in that
each white cell contains a nucleus. Adult humans have between
4,000 and 11,000 leukocytes per cubic millimeter of blood. In
infants, the number is essentially doubled. There is a ratio of
roughly one white cell for every 700 red cells. In leukemia,
there is an uncontrolled increase in the number of leukocytes.
In general terms, the white cells, each type with a specific
function, accomplish the following actions: (1) Protection of the
body from pathogenic organisms; and (2) participation in tissue
repair and regeneration. Whenever bacteria or other foreign
substances enter the tissues, large numbers of white cells
immediately travel through the walls of the blood vessels to the
site of disturbances. They take bacteria and any other foreign
materials into their own 
bodies where they are digested. White
cells are able to break up and carry away an object even as large
as a splinter or thorn in the skin. They also help in carrying
away dead tissue and blood clots which remain after a wound. Pus
is largely composed of white cells which have been drawn to the
infected area, as well as the dead and disintegrating tissue and
bacteria. During severe infections, the white cells may be
increased in the blood five or tenfold. Because of this, a blood
white cell count is made in order to confirm diagnosis in many
infections.
white blood cells (WBCs) which
are sometimes collectively called leukocytes, although some
authorities reserve that term to identify only the granulocytes.
White cells are irregular in shape and size, but generally are
larger than the red cells. They differ from the red cells in that
each white cell contains a nucleus. Adult humans have between
4,000 and 11,000 leukocytes per cubic millimeter of blood. In
infants, the number is essentially doubled. There is a ratio of
roughly one white cell for every 700 red cells. In leukemia,
there is an uncontrolled increase in the number of leukocytes.
bodies