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Immune System Response
April 7, 2011
Warm-up
How does the body prevent
pathogens from invading the
body? (What barriers protect the body?)
Pathogens are microorganisms that cause
diseases in humans
The first lines of defense
Skin- barrier that protects the body
Tears, Saliva, and Mucus protect the
natural openings in the skin (eyes,
nose, mouth, urinary tract)
– Enzymes break down pathogens
– pH (acidity) prevents growth of
pathogens
But what if a pathogen breaks past
these defenses and gets inside the
body?
Special cells in the blood protect the body by
producing an immune response to an
infection
• B-Cells
• T-Cells
• Macrophages (Phagocytes)
Website Animation Link
Immune System Response
• Questions from last night’s reading?
• Watch this video:
http://kidshealth.org/kid/htbw/_bfs_ISmovi
esource.html
(Phagocyte)
Pathogen
(bacteria)
Macrophage “eats”
pathogen and
breaks it into
pieces (antigens)
Receptor
Antigen
receptors
T-Helper cell recognizes
antigen/receptor complex
of macrophage
Antigen/receptor
complex
T-Helper
cell
Macrophage
releases signals
to activate
T-Helper cell
Helper T-cells activate next steps
Cell-mediated
response
Antibody-mediated
response
• If the pathogen has
infected body cells
and is spreading by
getting inside cells,
KILLER T-Cells are
activated to destroy
these cells.
• If the pathogen is in
the blood and is
spreading outside of
body cells, B-Cells
are activated to
produce antibodies
that help kill
pathogens
Antibody-mediated immune
response
B-Cell binds antigenmakes antigen/receptor complex
B-Cell
Antigen/receptor
complex
T-Helper cell binds complex
and releases signals to activate B-cell
Antigen/receptor
complex
Activating
signals
Antibodies bind to pathogens and
cause clumping. This makes it easier
for other cells to clear the pathogens.
Cell-mediated immune
response
T-Helper cell releases signals to
activate Killer T-Cells
T-Helper
Activating
signals
Killer T-Cell
Activated Killer T-Cell recognizes
cells infected with pathogens
Healthy cells
Infected cell
Killer T-Cells destroy infected cells
Processing of antigen
by macrophage
Activation of Helper T-Cells
Cell-mediated
response
(Killer T-Cells)
Antibody-mediated
response
(B-Cells)
(Click on a box to go to that slide)
What is an Antigen???
• Antigens are any
substance that
triggers the specific
defenses of the
antigens
immune system.
• Antigens are often
proteins on the
outside of viruses
and bacteria
What is an Antibody???
• Antibodies are
special proteins that
can bind to the
antigen on the
surface of a
pathogen and help
destroy it.
Antibodies “stick” to specific
antigen
Homework
due Friday4/8
• Find a current event article regarding the
immune system
– Title
– Source
– Summary of article