The bodys natural defense

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The Immune Response

• The bodys natural defense
• Against pathogenic organisms

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Nonspecific Defense Against a Pathogen Physical
and Chemical Barriers

Salivary glands
skin
Eyelashes and eyebrows
tears
Stomach acid
mucus
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Non-barrier, nonspecific defenses
Inflammation turns red from increased blood flow
to damaged area
Swelling indicates the body is sending more blood
and lymph to the affected area to help correct
the injury or fight the pathogen
fever
Infected cut wbc battled bacteria creates pus
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Phagocytes - WBC (white blood cells)
Eat pathogens
Alert other immune system cells that a pathogen
is present
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The Lymphatic System series of vessels carrying
lymph and phagocytes
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Natural Killer Cells WBC that kill
virus-infected cells
This target cell then dies along with the viruses
inside it!
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Interferons small proteins that cause normal,
uninfected cells to produce antiviral compounds
that interfere with viral replication they also
stimulate macrophages and NK into action.
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Antigen-Antibody Relationship
An ANTIBODY is produced in response to detection
of a foreign substance like the proteins on a
virus or bacteria cell.
A foreign substance that causes the production of
an antibody to destroy it is called an ANTIGEN
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Specific Cellular Defense
B-cell eats pathogen, breaks it apart, and
displays its proteins on the surface of the B
cell. Helper T cell, plasma cell, and memory B
cells then are involved in the antibody response
and remembering it for the next time.
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Steps of Specific Immune Response
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1. Macrophage (white blood cell) consumes a virus.
virus
macrophage
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2. Macrophage digests virus and displays viral
antigens on its surface
Antigen
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3. One helper T cell recognizes the antigen and
binds to the macrophage
Helper t cell
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4. Chemicals (interleukin-1 and tumor necrosis
factor), made by the macrophage and others
(interleukin-2 and gamma interferon) made by the
T cell, allow intercellular communication
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5. These chemicals instruct other helper T cells
and killer T cells to multiply. The B cells
multiply and produce antibodies.
Killer t cell
antibody
B cell
Helper t cell
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6. Killer T cells destroy cells that have been
infected by the virus (and unfortunately some
uninfected cells, too)
Killer t cell
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7. Antibodies released by B cells binds to
antigens on viruses this makes it easier for
macrophages to eat the viruses and helps destroy
the viruses themselves.
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8. When infection is controlled, suppressor T
cells stop the reaction. Memory cells remain to
respond quickly if same virus attacks again
Memory b cell
Suppressor t cells
Memory cell
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Allergies the immune system makes a mistake!

• Triggered by noninfectious agents such as pollen
  or pet dander
• Causes an inflammatory response that could be
  runny nose, sneezing, wheezing, hives, etc.
• Can be developed after years of exposure to the
  allergen the body seems to reach a critical
  exposure level.

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The End