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Essay Archive - The Immune System
The Immune System
The immune system is a group of cells, molecules, and tissues that help
defend the body against diseases and other harmful invaders. The immune system
provides protection against a variety of potentially damaging substances that
can invade the body. These substances include disease-causing organisms, such
as bacteria, fungi, parasites, and viruses. The body's ability to resist these
invaders is called immunity. A key feature of the immune system is its ability
to destroy foreign invaders while leaving the body's own healthy tissues alone.
Sometimes, however, the immune system attacks and damages these healthy tissues.
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