1. Immune System Response
April 7, 2011

2. 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

3. 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

4. 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

5. Immune System Response
Questions from last night’s reading?
Watch this video:

6. (Phagocyte) Pathogen (bacteria) Macrophage “eats” pathogen and
breaks it into
pieces (antigens)

7. Receptor
Antigen
receptors

8. T-Helper cell recognizes antigen/receptor complex of macrophage

9. Macrophage
releases signals
to activate
T-Helper cell

11. Helper T-cells activate next steps
Cell-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.
Antibody-mediated response
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

12. Antibody-mediated immune response

13. makes antigen/receptor complex
B-Cell binds antigen-
makes antigen/receptor complex
Antigen/receptor
complex
B-Cell

14. T-Helper cell binds complex and releases signals to activate B-cell
Antigen/receptor
complex
Activating
signals

17. Antibodies bind to pathogens and
cause clumping. This makes it easier
for other cells to clear the pathogens.

18. Cell-mediated immune response

19. T-Helper cell releases signals to activate Killer T-Cells
Activating
signals
Killer T-Cell

20. Activated Killer T-Cell recognizes cells infected with pathogens
Healthy cells
Infected cell

21. Killer T-Cells destroy infected cells

22. (Click on a box to go to that slide)
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)

23. What is an Antigen???
Antigens are any substance that triggers the specific defenses of the immune system.
Antigens are often proteins on the outside of viruses and bacteria
antigens

24. What is an Antibody???
Antibodies are special proteins that can bind to the antigen on the surface of a pathogen and help destroy it.

25. Antibodies “stick” to specific antigen

26. Homework due Friday4/8
Find a current event article regarding the immune system
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Source
Summary of article