Chapter 22, part 3

1. Chapter 22, part 3 The Lymphatic System and Immunity

2. SECTION 22-4Specific Defenses

3. Forms of immunity • Innate immunity • Genetically determined • Present at birth • Acquired immunity • Not present at birth • Achieved by exposure to antigen • Active immunity • Passive immunity

4. Figure 22.14 Types of Immunity Figure 22.14

5. Properties of immunity • Specificity – activated by and responds to a specific antigen • Versatility – is ready to confront any antigen at any time • Memory – “remembers” any antigen it has encountered • Tolerance – responds to foreign substances but ignores normal tissues

6. The immune system response • Antigen triggers an immune response • Activates T cells and B cells • T cells are activated after phagocytes exposed to antigen • T cells attack the antigen and stimulate B cells • Activated B cells mature and produce antibody • Antibody attacks antigen

7. Figure 22.15 An Overview of the Immune Response Figure 22.15

8. SECTION 22-5T cells and Cell-mediated Immunity

9. Major types of T cells • Cytotoxic T cells (TC) – attack foreign cells • Helper T cells (TH) – activate other T cells and B cells • Suppressor T cells (TS) – inhibit the activation of T and B cells

10. Antigen presentation • Antigen-glycoprotein combination appears on a cell membrane • Called MHC proteins (Major Histocompatibility Complex) • Coded for by genes of the MHC • T-cells sensitive to the antigen are activated upon contact

11. MHC classes • Class I – found on all nucleated cells • Class II – found on antigen presenting cells and lymphocytes

12. Lymphocytes respond to antigens bound to either class I or class II MHC proteins • Antigen recognition • T cell membranes contain CD markers • CD3 markers present on all T cells • CD8 markers on cytotoxic and suppressor T cells • CD4 markers on helper T cells

13. Figure 22.16 Antigens and MHC Proteins Figure 22.16

14. Figure 22.16 Antigens and MHC Proteins Figure 22.16a

15. Figure 22.16 Antigens and MHC Proteins Figure 22.16b

16. Activation of CD8 cells • Responds quickly giving rise to other T cells • Cytotoxic T cells – seek out and destroy abnormal cells • lymphotoxin • Memory TC cells – function during a second exposure to antigen • Suppressor T cells – suppress the immune response

17. Figure 22.17 Antigen Recognition and the Activation of Cytotoxic T Cells Figure 22.17

18. Figure 22.17 Antigen Recognition and the Activation of Cytotoxic T Cells PLAY Animation: Cytotoxic T Cell Activation Figure 22.17

19. Activation of CD4 T cells by antigens presented on class II MHC proteins • Produces helper T cells and memory T cells • Activated helper T cells • Secrete lymphokines that coordinate specific and nonspecific defenses • Enhance nonspecific defenses • Stimulate the activity of NK cells • Promote activation of B cells

20. Figure 22.18 Antigen Recognition and Activation of Helper T cells PLAY Animation: Antigen Recognition and Helper T Cell Activation Figure 22.18

21. Figure 22.19 A Summary of the Pathways of T Cell Activation Figure 22.19