By Rich Silver
How important is your
immune system?
Without it, your body
would quickly begin to decay
as bacteria, viruses, fungi,
parasites, and diseases invade
the body and eat away at your
cells. Even an immune system
functioning at partly reduced
effectiveness leaves the body
vulnerable to these invading
substances.
The key to maintaining a
healthy immune system is to
know what weakens it…and
what strengthens it.
How the immune
system functions
The job of your immune
system is to defend the body
against foreign or dangerous
substances that attack it. These substances can come from
outside the body or unhealthy
cells that may develop inside
the body.
Your body has several lines
of defense against invaders.
The first are: your skin,
the membranes lining the
respiratory, digestive, urinary,
and reproductive tracts, and
sticky mucus and fluids in your
eyes, nose, and mouth.
The second, and most important
line of defense, is your immune
system; a complex system
of white blood cells that must
work synergistically together to
be effective. There are 16 different
types of white blood cells,
and some of the most important
are macrophages, Natural Killer
(NK) cells, T cells, and B cells.
Here's how they work.
Suppose someone
sneezes near you…
Harmful germs and agents
rush into your body. The
largest white cells in your
body, macrophages, meet these
invaders and like little Pacmen,
begin swallowing and digesting
them.
Then, your fiercest and most
important white blood cells, NK
cells, join the attack, identifying
and killing any harmful cells.
They inject these invader cells
with cytotoxic granules and they
quickly explode. When a full out
attack is needed, your NK cells
sound the alarm to coordinate
and bring in reinforcements,
T cells and B cells.
NK cells are vitally important
to your front line of defense
because they not only sound the
alarm for a coordinated effort
in your immune system…but
they are natural born killers—no
training necessary.
T cells on the
other hand…
…do have to go through a
"training program" before they
can graduate and become killers
of invaders. T cells are formed in
the bone marrow. But they then
have to "go to school" in the
thymus gland, which is behind
your breastbone.
During training, they mature
and learn the difference between
good cells that they're supposed
to leave alone—and bad, invading
cells that they're supposed
to kill off. They aren't allowed to
leave the classroom (the thymus)
until they get this right.
But sometimes T cells skip
class (scientists aren't sure
why) and they can't distinguish
good from bad cells. When this
happens, T cells may attack
your own body and destroy
good cells. This is called an
autoimmune response. Allergies, lupus, and rheumatoid arthritis
are examples of the immune
system attacking healthy cells.
Your bone marrow
also produces B cells
B cells are white blood cells
that produce antibodies. Each
antibody is a specialist. And
because each antibody attaches
itself to a specific type of invader,
this action signals all types of
white blood cells to join the
attack against invaders.
As you can see, white blood
cells are critical to a healthy
immune system and are a
measure of good health. For
men, a strong immune system
has a normal white cell count of
5,000 to 10,000 microliters. For
non-pregnant women, about
4,500 to 11,000. So what weakens
and what strengthens the
immune system?
|
STORY HIGHLIGHTS
-
Even an immune system
functioning at partly reduced
effectiveness leaves the body
vulnerable to these invading
substances.
-
The key to maintaining a
healthy immune system is to
know what weakens it…and
what strengthens it.
-
NK cells are vitally important
to your front line of defense
because they not only sound the
alarm for a coordinated effort
in your immune system
-
T cells are formed in
the bone marrow.
|
