2. “What if pathogens get
in?”
• White blood cells take over and specifically identify and
eliminate the pathogen.
• White blood cells = “soldiers”
• Immune Response
3. Organs of the Immune
System
White blood cells
called leukocytes
Made thymus and
bone marrow
Stored tonsils,
spleen, and lymph
nodes.
4. How does your body
know
there is an invader?
• All pathogens have “distinct” antigens.
• Antigens are marker proteins- trigger immune
response
• Your body must recognize antigens in order to
identify and defeat the pathogen.
• Normal cells also have antigens.
Antigen
6. Antibodies
• Your white blood cells produce antibodies in
response to specific antigens.
• These are specific to each pathogen.
• All pathogens are unique, your immune system
has to prepare a specific defense against each
invader.
• If you makes/have the antibodies it can kill the
pathogen and you can fight the infection.
• B-cells (type of white blood cell) make the
antibodies!
7. Building “Immunity”
• What happens if a pathogen makes it
past the first lines of defense and avoids
the inflammation response?
• Your body must “actively” fight the
disease.
• This takes time.
• This requires a special group of white
blood cells lymphocytes.
8. “The Soldiers”
• Many types of WBC
work together during
the immune response to
fight the infection.
• Macrophages
• Lymphocytes
9. “The Soldiers”
• 3 major classes of
lymphocytes:
1) B-cells (plasma cells)
2) T-cells
-Helper T cells
-Killer T cells
-Suppressor T cells
3) Memory cells
10. Step #1 “Invader
Identification”
• Macrophages identify pathogen, eat it, display
antigens, signal helper T cells (interleukin-1).
• Body temperature will increase (interleukin-1) in
attempt to slow down pathogen.
11. • Helper T cells release interleukin 2 – signals
help other leukocytes (other T-cells and B-cells)
12. Step #2 “Cloning
Phase”
• B cells make antibodies - lock onto
antigens.“Marked for death.”
Antibodies
Antigen
13. Step #3 “The Attack Phase”
• Killer T cells kill infected body cells.
14. Step #3 “The Attack
Phase”
• Macrophages clean up- eating pathogens,
damaged body cells, etc.
• Suppressor T cells “call off the troops” stopping
the immune response.
15. Step #4 “Memory
Phase”
• Memory cells “remember” the attack and
recognize a pathogen if it re-enters body.
• Primary vs. secondary immune response
16. Active vs. Passive
Immunity
• Active = your body must fight off the
disease to build up antibodies. Ex.)
Fighting an infection or Vaccination
• Passive = receiving antibodies from an
outside source. Ex.) Breast feeding