In basic terms, the role of the immune system is to identify those
things that naturally belong or are not harmful to the body, and those
that are foreign. Once a foreign "invader" (called an antigen)
is detected, the immune system then neutralizes or destroys it. The
immune system then has the amazing ability to remember the antigen
through two basic means known as cell-mediated immunity and humoral
immunity.
In cell-mediated
immunity, white blood cells called T lymphocytes, identify and then
destroy cancerous cells, viruses and micro-organisms like bacteria
and fungi.
Humoral immunity
involves the production of antibodies. These are not cells, but special
proteins whose chemical structures are formed to match the surfaces
of specific antigens. When they encounter their specific antigens,
antibodies either damage the invasive cells or alert the wihite blood
cells to attack.
In both cell mediated
and humoral immunity, white blood cells are the body's first line of
defense. They are larger than red blood cells, move by themselves in
the bloodstream and are able to pass through cell walls. These qualities
enable them to move quickly to the site of infection or injury and
begin repair.
Keeping the immune
system functioning properly means avoiding those factors which cause
weakness. Some examples are: stress, the overuse of antibiotics and
other drugs, exposure to environmental pollutants, inadequate nutrition
and/or poor living habits.
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