Transcript The Immune System Pathogen: Viruses, bacteria, and other microorganisms that cause disease are called pathogens. Infection: Invasion of the tissues of body by.

The Immune System
Pathogen: Viruses, bacteria, and other microorganisms that
cause disease are called pathogens.
Infection: Invasion of the tissues of body by pathogens.
Defenses Against Infection
1. First line defenses:
- Skin
- Urine
- Sweat
- Membranes lining the body passages
- Tears
- Mucus
- Saliva
- Stomach acid
The Immune System
2. Second line defenses:
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Inflammatory response is a reaction of the body that causes
swelling, redness, warmth and pain in the area of an infection.
Cells that are damaged from the infection release certain
chemicals. These chemicals increase the flow of blood to the
infected area. The increased blood flow causes puffiness and
warmth and attracts phagocytes.
The Immune System
3. Third line defenses:
When the inflammatory response defense is insufficient, the
pathogen is targeted for destruction by the body’s immune
system.
The immune system recognizes, attacks, destroys and
remembers each kind of pathogen or foreign substance that
enters the body.
It does this by producing antibodies and specialized cells that bind
to and inactivate pathogens.
For each kind of pathogen, the immune system produces
antibodies or cells that are specific to that pathogen.
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