Transcript What could have caused this?

Aim: How does our body defend us
from pathogens?
Pathogens
Any disease-producing
agent especially a virus,
bacterium, fungus, or
parasite.
Immune System
Made of proteins, cells, and
tissues that identify and
defend the body against
foreign chemicals and
organisms
How many lines of defense
make up our immune system?
• 3!!
What is the difference between
a nonspecific and specific
immune response?
• Nonspecific: Targets any pathogen or
infected cell
• Specific: Targets only one pathogen or
cells infected by the same pathogen
Types of
White Blood cells
– Phagocytes: engulf and destroy any
pathogens or infected cells
– Lymphocytes: recognize specific invaders
1) B Cells – produce antibodies and memory
cells
2) T Cells – attack abnormal or infected cells
and activate other WBCS
– NK Cells: kill cancer cells
How does our immune system
identify foreign cells?
Antigen
Recognition proteins on our
cells (self) are not targeted
by our immune system.
• Protein markers “ID tags”
on the cells of pathogens
• Antigens identify the
invader as foreign (nonself).
1st Line of Defense
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Skin
Mucus/Cilia
Tears in eyes
Acid in stomach
Urethra (expelling
of urine)
Is
this a specific or nonspecific
defense?
Nonspecific!!!
2nd Line of Defense
Inflammatory
Response
What are the four major
characteristics of the
inflammatory response?
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Redness
Swelling
Heat Production
Pain
WHY??
Due to increased blood
flow to the area of
infection
Which types of white blood cells
are active during the inflammatory
response?
Phagocytes:
White blood
Cells that
Eat a pathogen
Is this specific or
Nonspecific defense?
What is happening in your
lymph nodes during the
inflammatory response?
• Preparing the 3rd line of defense to
attack the pathogen!
• B cells and T cells
• Specific Defense
Lymphocytes (B Cells)
• They can make
antibodies!!!
What are Antibodies?
Pathogen
Antibodies
Antigens
• They are “Y”
shaped
proteins that
help to fight
against
pathogens
How many antibodies exist for
one antigen?
Antibodies are made specifically to
match the shape of the antigen.
1 antigen = 1 antibody
What does this remind you of?
B Cells
B cells have specific receptors that bind with specific
antigens on pathogens. Once bound, B cells are
activated and become antibody producing factories
Produce
Antibodies
How do antibodies destroy pathogens?
• Antibodies bind to all of
the antigens on the
pathogen…
• This can kill the pathogen
itself OR
• Acts as a marker for a
phagocyte to engulf
T Cells
1) Cytotoxic T Cells – can kill infected cells by
shooting toxins into the cell membranes
T Cells & Cell Mediated Immunity
2) Helper T Cells – help to activate more B and T cells
Our Immune System has a good
memory!
** After the first response, the immune system “remembers”
specific pathogens by leaving behind memory cells that protect
the body for years