Immune System

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Lines of Defense There are 3 lines of defense in

the body. The first 2 are nonspecific (they

attack everything); the 3rd is specific (it attacks only the pathogens it is responsible for)

The first line is the skin and mucous membranes that stop invaders from entering the body.

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The second line of defense is internal (but still nonspecific)

The inflammatory response is a series of events that helps prevent infection.

Injured cells will release histamines that causes vessel dilation (increases blood flow)

Blood flow brings white blood cells to the area.

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The body will also increase the internal temperature to help kill the invader.

Complement proteins circulate around the body and attempt to punch holes in invaders.

White blood cells (like neutrophils and macrophages) also engulf and destroy.

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Immune Response If the invaders get through the

first 2 lines, the third line (specific) is activated.

Cytotoxic T cells attack and kill infected cells.

B cells label invaders for later destruction by macrophages (if it enters again)

Helper T cells activate both cells.

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Every cell has a surface protein on it that helps other cells recognize it (an antigen)

If it is foreign (I.e the flu virus) it triggers an immune response.

The body’s own cells should not attack themselves as the antigens should be recognized (autoimmune diseases)

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When an invader enters the body and it makes it to the 3rd line of defense, the antigens of the invaders triggers the plasma cells to release antibodies.

Each antibody binds to foreign antigens.

Plasma cells divide rapidly, producing more and more antibodies.

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All the antibody-antigen clumps allow cytotoxic T cells to easily identify and kill.

One way to prepare the body is through vaccination.

A vaccine contains a dead or weakened pathogen (or DNA from pathogen)

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The vaccine triggers an immune response and develops antibodies and memory cells against that pathogen.

If the body sees it again, it already knows how to kill it.

Some diseases have multiple strains (flu) so vaccination helps, but cannot totally eradicate all strains.

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http://www.humanillnesses.com/General-Information-and-Infectious-Diseases-A-Co/Body-Defenses.html

http://srxa.wordpress.com/2010/09/03/ http://www.iba-go.com/streptamer/str_tcell.html

http://www.web-books.com/eLibrary/Medicine/Physiology/Immune/Antigen.htm

http://www.accessexcellence.org/AE/AEC/CC/making_vaccines.php