1. The Body’s Defense System
How does the body identify and destroy pathogens?

2. What is a pathogen?
a microorganism such as a virus, bacterium, prion, or fungus, that causes disease in a plant or animal

3. Prions Infectious Protein
No DNA or RNA
NOT LIVING
AKA spongiform (like a sponge) encephalopathies (pathogen of the brain)
Mad Cow Disease - Cows
Scrapie - sheep
Kuru – humans New Guinea,

5. Virus Has two components Protein covering
Nucleic acid (either RNA OR DNA, rarely both) inside
Infect and “take over” the cell’s replication machinery
Colds, Influenza, HIV

6. Virus

7. Cold and HIV Virus

8. Streptococcus Bacteria
Living prokaryote!

9. Non-specific vs. Specific Immune Response
Barriers
Separate the organism from its environment
Nonspecific immune response – second l
Inflammatory Response
Repel and destroy foreign “cells”
Specific immunity
How lymphocytes identify and remember certain types of invasive bacteria, viruses, toxins.
Create a “rapid defense system” for any second attack

10. First Line of Defense - Barriers
Skin
Mucous membranes
Secrete mucus (all “openings” to the environment)
Mucus contains lysozyme (kills bacteria)
Others
Cilia (Resp. system)
Stomach acid (low pH kills bacteria)
Enzymes (lysozyme in tears)
Respiratory tract

12. Second Line: Non Specific Immunity
Inflammatory Response
Histamine triggers the response
Increases the permeability of capillary membranes (lets white blood cells out of the capillaries)
Phagocytes/macrophages – ingest invaders
Natural Killer cells – lymphocytes that provide a rapid
response to a viral infection.
Help contain a viral infection
while antibodies are being made.

13. Inflammatory Response
Increased blood flow
RESULT: Redness, swelling, pain, warmth,
Clotting (if blood vessel damaged)

14. Match these to the conditions (next page)

15. Effects of inflammation
Pain
Heat
Swelling
Redness
Loss of function (sometimes)
Chronic (long term) inflammation (depending on location 
Periodontitis (gums)
Atherosclerosis (blood vessels)
Crohn’s disease (intestines)
Hayfever (respiratory system)
Arthritis(joints)

16. Fever
Increase body metabolism , speeding up the repair process (only up to 104 F)
Slow down the reproduction of some bacteria and viruses .
Makes YOU slow down and “rest”

17. How does fever help? (1) Fever slow down some bacteria and viruses.
(2) Fever increase metabolism (enzymes work faster up to 104 F)
(3) fever makes a patient feel ill, condition which makes the patient more likely to rest.

18. Protein Production Complement proteins Interferon
Stimulate inflammation and phagocytosis
Interferon
Send warning signals to neighboring cells
Released by a cell which was attacked by a virus

19. How does the body know to “stop” the inflammatory response
Programmed cell death (apoptosis)
Based on lack of presence of pathogen (foreign antigens)
Signal sent to “self destruct”.

20. What if the bacteria is too strong?

21. Specific Immunity
Cells and Tissues that learn about and learn to recognize and attack foreign substances (based on antigen recognition)
Include
Macrophages(from general response)
T-cells
B cells

22. Role of each Cell Cell mediated immune response
Macrophages/phagocytes
– engulf (eat) foreign invaders
T cells
- identify and destroy infected cells; communicate with B cells
Humoral Immune response
B cells
– produce antibodies, immune memory
Antibodies
– specific proteins design to restrict spread of pathogen

23. Chemicals “call” cells
When macrophage “eats” the bacteria it “displays” antigens
Helper T binds to antigens
Result: chemical message released
more Helper T made
Killer T activated
Communicate with B cells

24. Chemical signals 

25. B cells create Antibodies
Bind to a surface antigen on bacteria and clumps them together so that macrophage can “eat them”
Complement proteins
Put holes in bacterial cells
Can inactivate or destroy toxins

26. Antibodies and complements
Antibodies bind to antigens

27. Once all is under control
Chemical messages decrease B and T cells
IMMUNE MEMORY
Memory B cells are formed
Future rapid response cells
Circulate in blood

28. Memory T Cell
Suppressor T Cell
Memory B Cell

29. Memory Cells
The next time that an individual encounters that same antigen, the immune system is ready to destroy it quickly.

30. What prevents Reinfection?
MEMORY CELLS
Long term protection against re-infection for life
How?
Memory B cells remain in the blood. (Bone marrow can remake as needed)
Recognize antigen (second time response)
Rapid and large production of specific antibodies

31. Ways to obtain immunity
Short –term immunity
Some vaccines or fluids containing antibodies
Infants have antibodies from mother
Due to blood exchange during pregnancy
Due to mother nursing child
Long-term immunity
Stimulated by infection
Can be obtained through vaccines made from infectious agents that are not infectious, but do cause antibodies to form

32. Short term vs. Long term Immunity
Body has been exposed to infective agent
Disease or vaccine
Short term immunity
Individual given antibodies (but the body has not learned how to make more)

33. Vaccines vs Antibiotics vs. Antivirals
Create a table with three columns and four rows
In the first column
Vaccine
Antibiotic
Antiviral

34. Vaccines, Antibiotics, Antivirals
Column 1 – When are they used (before or during or after infection?)
Column 2 – What are they effective against?
Column 3 - Do they treat, prevent, or cure?
Column 4 Do you have other questions or comments to add?

35. Virus consumed by a macrophage
2. Macrophage displays the virus antigens
3. Helper T-Cell recognizes “enemy” . Call in the troops.
4. B cells and Killer T Cells are manufactured
5. B cells produce antibodies that bind the virus. Killer T Cells destroy infected body cells.
6. Suppressor T cells stop production of defense.
7. Memory cells remain for future rapid response.