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Immunity part iv acquired immunity
- 1. Immunity: Part IV Acquired Immunity
- 2. Remember: Types of Immunity • Innate • Acquired – Is the body’s second major kind of defense – Involves the activity of lymphocytes Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
- 3. • A summary of innate and acquired immunity INNATE IMMUNITY Rapid responses to a broad range of microbes Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings ACQUIRED IMMUNITY Slower responses to specific microbes External defenses Internal defenses Skin Mucous membranes Secretions Phagocytic cells Antimicrobial proteins Inflammatory response Natural killer cells Humoral response (antibodies) Cell-mediated response (cytotoxic lymphocytes) Invading microbes (pathogens)
- 6. Properties of Immunity 1.Specificity 2.Versatility 3.Memory 4.Tolerance
- 8. Figure 14.16
- 10. Figure 14.12
- 11. T Cells & Cell-Mediated Immunity • T Cells must be activated by exposure to antigen • T Cells recognize antigens when they are bound to membrane receptors of other cells • Antigen membrane receptors are called – MAJOR HISTOCOMPATIBILITY COMPLEX PROTEINS • Class I MHC • Class II MHC
- 12. T Cells & Cell-Mediated Immunity • MHC Proteins • Class I – Found on the surface of all nucleated cells – Peptides produced inside the cell are displayed on the surface by Class I MHC proteins. • Class II – Found on the surface of lymphocytes & phagocytes • Called ANTIGEN-PRESENTING CELLS (APCs)
- 13. Types of T Cells 1. Cytotoxic T Cells 2. Helper T Cells 3. Memory T Cells 4. Suppressor T Cells
- 14. Notes Handout
- 15. Activation of Cytotoxic T Cells MHC Class I clip
- 16. Helper T Cells • Activated by exposure to antigens presented by Class II MHC proteins • Activated helper T cells perform two functions: 1. Coordinate specific & nonspecific defenses 2. Stimulate both cell-mediated & antibody-mediated immunity • Activated helper T cells divide to produce: – More activated helper T cells – Memory T cells • helper T cells clip
- 17. Memory T Cells • Produced upon initial exposure to antigen, but do not respond to the antigen at that time. • Provide a no-delay response to any FUTURE exposure to the same antigen – Immediate differentiation into cytotoxic T cells and helper T cells
- 18. Suppressor T Cells • Activated suppressor T cells dampen the responses of other T cells and B cells – Secrete suppression factors • Act after the initial immune response
- 19. Notes Handout
- 20. Sensitization & Activation of B Cells
- 21. Sensitization & Activation of B Cells
- 22. Sensitization & Activation of B Cells
- 23. Sensitization & Activation of B Cells
- 24. Notes Handout
- 27. antibody clip
- 28. Antibody (IgG) Function • Neutralization • Agglutination and precipitation • Activation of complement • Attraction of phagocytes • Enhancement of phagocytes • Stimulation of inflammation
- 29. Notes Handout
- 30. Summary of the Immune Response and Its Relationship to Nonspecific Defenses
- 31. Notes Handout
- 32. Integration of the Lymphatic System with Other Systems
Notas do Editor
- Innate Immunity Genetically determined Present at birth Independent of previous exposure to antigens Acquired Immunity Not present at birth Appears after exposure to an antigen Can be passive or actived
- T Cell activation does not usually result from direct lymphocyte-antigen interaction. T Cells are seldom activated by the mere presence of antigens alone.** **T Cells recognize antigens when those antigens are bound to membrane receptors of other cells. MHC Proteins Class I Class II
- Cytotoxic T Cells = Killer T Cells
- Among the many T cells produced upon initial exposure to an antigen. Do not respond to the antigen during initial exposure. Remain on reserve until subsequent exposure. Immediately differentiate into killer T cells upon subsequent exposure. This rapid response generally destroys invading pathogens before they can cause the body to produce signs and symptoms of disease.
- Suppression does not occur immediately bc suppressor T cells are activated more slowly than other types of T cells.
- A B Cell is sensitized by exposure to antigens (step 1). Once antigens are bound to antibodies in the B cell membrane, the B cell displays those antigens in its cell membrane. Activated helper T cells encountering the antigens on the sensitized B cell membrane then release cytokines that trigger the activation of the B cell (step 2). The activated B cell then divides, producing memory B cells and plasma cells that secrete antibodies (step 3).
- Antibody aka IMMUNOGLOBIN (IgG).
- antigen-antibody complex Antibodies do not bind to the entire antigen as a whole. They bind to certain portions of its exposed surface, regions called ANTIGENIC DETERMINANT SITES. The specificity of that binding depends on the 3D “fit” between variable segments of the antibody molecule and the corresponding sites of the antigen. A complete antigen has at least two antigenic determinant sites, one for each arm of the antibody molecule. Exposure to a complete antigen can lead to B cell sensitization and an immune response. Most environmental antigens have multiple antigenic determinant sites; entire microorganisms may have thousands.