Immune System

1. Immune System Body’s Defenses

3. Immune Responses • Passive • Formation of antibodies • To the fetus thru the placenta, thru breast milk, thru administration of plasma (artificial) • Active • Formation of your own antibodies • Vaccinations • by contracting an infectious disease by exposure of an antigen

4. Components of the immune system

5. 2 categories of Defenses • Non-specific • Specific

6. Types of Defenses • Nonspecific defense • mechanisms are general and protect against many types of pathogens • Barriers to entry • Inflammatory rxns • Protective proteins

7. Types of Defenses: non-specific • Pathogens: • bacteria, fungi, protozoa, and viruses that cause infection

8. Barriers to entry: non-specific

9. Layered Defenses • Physical barriers prevent pathogens such as bacteria and viruses from entering the organism.

10. Barriers to entry: Bodily secretions

11. Barriers to entry

12. Chemical Barriers to Entry • Enzymes • Acids: stomach acid

13. Chemical Barriers • Complement System http://www.youtube.com/watch?v=vbWYz9XDtLw

14. Figure 16.21

15. Inflammatory Response

17. WBCs

19. Neutrophils 1stWBC to scence • Phagocytes capable of diapedesis • Hallmark of acute infection • First to arrive on scene • 40-70%

21. Eosinophils • Mediate for allergies • Limited phagocytic activity • Strong Chemotaxis • Attract to injury and infection • Destroys Antigen/Ab complex • 2-4%

22. Basophils • Mast cells • Releases histamine: vasodialator • Heparine: anticoagulant • Releases serotonin/Kinin • .5-1% (smallest population)

23. Monocytes • Scavengers • Transform into macrophages, eating bacteria, viruses and tissue debris • 3rd line of defense • 3-8%

24. Monocyte

25. Lymphocytes • Acquired immune response • SPECIFIC defense system • 20-25% • Forms 2 types: • T cells: attack all foreign cells • B cells: produce Ab to get rid of bacteria and viruses

27. Blood cells are produced in the bone marrow from a pluripotent stem cell that can become either a WBC, RBC or Platelet

33. http://www.dnatube.com/video/2441/Uptake-of-Bacteria-by-Phagocyteshttp://www.dnatube.com/video/2441/Uptake-of-Bacteria-by-Phagocytes

34. Specific Defenses Immunity is a specific defense mechanism. It is resistance to a particular pathogen or its toxin or metabolic by-product. Immunity is based upon the ability to distinguish self molecules from non-self. Molecules that can elicit an immune response are antigens.

35. Antigens • The lymphatic system responds to non-self or foreign antigens, but not to self antigens. • Shape of antigens allow immune system to be specific • Antigens: molecules that can elicit an immune response and each having their own receptor • may be proteins, polysaccharides, glycoproteins, or glycolipids.

38. Antigen-Presenting Cells • Macrophages alert lymphocytes by displaying antigens from engulfed cells. • Foreign antigens are attached to the macrophage surface by a self protein, part of the major histocompatibility complex (MHC).

39. Cellular Immune Response • Helper T cells destroy infected cells and clean up pathogens • T cells attach to foreign, antigen-bearing cells, cell-to-cell contact. • Cytokines or lymphokines enhance cellular response to antigens.

40. Helper T cells produce chemical signals to activate cytotoxic T cells, which are WBC carrying pathogen-specific receptors on their surface • Kill cancer cells and attack foreign tissue

41. Lymphocytes Origin • Red bone marrow releases undifferentiated lymphocytes into the circulation. • Some become T lymphocytes or T cells in the thymus. Figure 16.16

43. The Immune Response http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter24/animation__the_immune_response.html

44. HumoralImmunityRemoving Pathogens at large • B cells secrete antibodies into the blood: antibody-mediated immunity. • Helper T cells activate B cells in response to macrophage presentation of antigens. • Stimulated B cells produce plasma cells or memory cells. • Plasma cells produce antibodies.

45. AB are released by plasma cells and circulate in blood and lymph • Ab attach to pathogens, similar to specific binding of cytotoxic T cells • AB/Antigen complex are then destroyed by general defense like macrophages or proteins that puncture pathogen’s membranes

46. http://bcs.whfreeman.com/thelifewire/content/chp18/1804s.swf

47. Types of T Cells • Helper T cells • stimulate B cells to produce antibodies • CD4 cells are prime targets of HIV • Memory T cells • produced upon initial antigen exposure and protect against delay in future exposure • Cytotoxic T cells • release perforin to destroy cells that present foreign antigens

48. B Cell Activation • Activated helper T cell releases cytokines. • Cytokines stimulate B cell proliferation. Figure 16.19

49. B Cell Activation • Some B cells become plasma cells that secrete antibodies that bind antigens. • Antibodies (immunoglobulins) are globular proteins composed of four chains. • Ends of the molecule contain antigen-binding sites.

50. Long Term Protection • Memory Cells