1. This week: Protection from Pathogens

2. esophagus stomach Taking in food and oxygen exposes us to pathogens

3. Pathogen: a disease causing agent

4. Ebola E. coli Fungus from soil Phage virus various pathogens

5. The Immune System Non-specific: –barriers Specific : –B-cells -> antibodies –T-cells Fig 43.2

6. Non-Specific Immune System Barriers: Skin- Dry Inhospitable Competition Secretions (lysozyme) Hairs and Mucus (protect openings) Traps particles, swallowed Stomach acid kills pathogens Fig 43.2

7. Skin protects us from most pathogens

8. Fig 43.2

9. esophagus stomach Stomach acid kills pathogens Hairs and Mucus (protect openings) Traps particles

10. Non-Specific Immune System Barriers: Skin- Dry Inhospitable Competition Secretions (lysozyme) Hairs and Mucus (protect openings) Traps particles, swallowed Stomach acid kills pathogens Fig 43.2

11. The Immune System Non-specific: –barriers Specific : –B-cells -> antibodies –T-cells Fig 43.2

12. The Specific Immune System

13. B-cells and T-cells move through the circulatory system scanning for pathogens

14. B-cells develop in bone marrow T-cells in the thymus

15. B-cells make and secrete antibodies Fig 43.14

16. Constant region Variable region An Antibody Fig 43.10

17. Antibodies recognize and bind to antigens Fig 43.10

18. Marked for destruction by WBC B-cells make antibodies that bind to antigens marking them for destruction Fig 43.19

19. Fig 43.14 Each B-cell/antibody recognizes a specific antigen

20. Fig 43.13 B-cell DNA rearranges to make a unique and random gene

21. Fig 43.14 Each B-cell/antibody recognizes a specific antigen

22. Marked for destruction by WBC B-cells make antibodies that bind to antigens marking them for destruction Fig 43.19

23. Fig 43.21 Antibody binding to antigens can lead to... Neutralization Engulf and Destroy

24. What about damaged or abnormal cells? Viral infections Cancer cells Non-functional cells

25. T-cells recognize and destroy abnormal cells Fig 43.18

26. Helper T-cells activate B-cells and Killer T-cells CB 43.17

27. Killer T-cells recognize and destroy abnormal cells Fig 43.18

28. Helper T-cells activate B-cells which produce antibodies CB 43.19

29. CB 43.16

30. Fig 43.15 It can take 7-14 days to produce sufficient antibodies to eliminate a pathogen

31. Memory B-cells make the response to a second exposure more rapid This is how vaccines work. Fig 43.14

32. Vaccines work via memory B-cells that make the response to a second exposure more rapid Fig 43.15

33. Next: Vaccines, when politics and science collide...