1. Immune System

2. Defense system Nonspecific Immunity Specific Immunity

3. First line of defense: Surface membrane barriers Skin and mucous membrane – Layered epidermis and shedding of epithelial cells – Sebum inhibits growth of bacteria and fungi – Mucous traps microbes, dust and pollutants. Lacrimal apparatus Saliva Vaginal secretions Flow of urine Defecation and vomiting Gastric juices destroy bacteria and their toxins

4. Text Table 21.2 Oral CavityAntimicrobial enzymes in saliva (e.g. lysozyme and lactoperoxidase) inhibit microbes, Resident flora SkinpH (3-5), sebum Respiratory Cavity Hairs, cilia, mucociliary escalator, Sticky mucus (lysozyme) traps dust and microbes. GI Tractlow pH and digestive enzymes, flushing action EyesTears, (lysozyme). flushing action VaginapH, flushing action, resident flora

5. Second line of defense: chemical and cellular defenses Antimicrobial proteins – Interferon – Complement – Transferrins Natural killer cells Phagocytes – Neutrophils – Dendritic cells – Macrophages Wandering Fixed – Eosinophils

6. Interferons Produced by lymphocytes, macrophages and fibroblasts. Interfere with translation of viral proteins Degrade viral RNA Activate macrophages and NK cells Interferon Animation

7. Complement Complement Cascade Animation

8. Phagocytosis

9. Phagocyte Mobilization

10. Fever Regulated my hypothalamus Due to pyrogens secreted my leukocytes & macrophages Causes liver and spleen to sequester zinc and iron Increases metabolic rate (repair)

11. Inflammatory response Stages Inflammation AnimationInflammation Animation Release of Chemical Alarms Vasodilatation & Permeability of BV Emigration of phagocytes: Dispose cellular debris & pathogens Sets the stage for repair Prevent spread of damaging chemicals & pathogens Signs of inflammation – Redness – Heat – Swelling – Pain – Impairment of function

12. Comparison of Immune Cells

13. Adaptive Resistance Specificity—recognition of particular antigens Memory—remembers previously encountered antigens Systemic—immunity is not restricted to the initial infection site Immune responses – Antibody-mediated or humoral immune responses (late 1800s) – Cell-mediated immune responses (mid 1900s)

14. T Lymphocytes CD4 T cell - also known as a T Helper (Th) cell CD8 T cell - also known as a Cytotoxic T (Tc) cell Cytotoxic T

16. Antigens and antigen receptors Antigens can be entire microbes, parts of microbes or chemical components of pollen, egg white, blood cells,…….

17. Self antigens: MHC proteins Antigens on our own cells are self-antigens MHC proteins are glycoproteins that mark the cell as self. – Class I MHC proteins are on all body cells. Receptors on T C – Class II MHC proteins are only on certain cells that act in the immune response. Receptors on T H – Antigen Processing Antigen Processing

18. Immunocompetence T and B cells that have not been exposed to an antigen are naïve. Binding with an antigen completes differentiation into functional B and T cells. B cells mature in the bone marrow. T cells mature in the thymus.

19. Antigen receptors Genes determine what foreign substance will be recognized. An antigen determines which T or B cells will be activated. Lymphocytes make over a billion different receptors. Gene segments of a few hundred bits are reshuffled and combined--somatic recombination. The newly assembled gene is expressed as a receptor on the cell surface.

20. Humoral immune response Antigen challenge—the meeting between a naïve immunocompetent lymphocyte and an invading antigen. Occurs in lymphoid tissue such as spleen or lymph node. If antigen challenge is presented to a B cell then the humoral immune response is provoked.

21. Clonal Selection Monoclonal Antibody Production Monoclonal Antibody Production

22. Antibodies “immunoglobulins”

23. Immunoglobulin classes IgD is attached to B-cell plasma membrane IgM is released during primary response. Indicates current infection. IgG is the most aboundant. Can cross placenta & blood vessel walls. IgA found in body secretions prevents attachment to body surfaces. IgE causes release of histamine (allergies) by attaching to mast cells & basophils.

24. Immunological memory Primary immune response Secondary immune response

26. Antibody defense: PLANe Precipitation Lysis: Complement fixation and activation Agglutination Neutralization Enhancing phagocytosis

28. Cell-mediated immunity Antibodies can only inactivate an antigen and NOT destroy it. Antibodies prepare an organism for destruction by innate defenses. T cells can only recognize and respond to processed fragments of protein. T cells are suited for cell to cell interaction and target body cells infected by virus, bacteria and abnormal or cancerous body cells or cells that are transplanted or infused.

29. Cell-mediated immunity: T-cells Activation of T cells—T cell receptors bind to antigen presented by the antigen-MHC complex. CD4 and CD8 proteins interact with antigen and help maintain MHC-antigen coupling. Types of T-cells – Helper T cells (CD4) – Cytotoxic T cells (CD8) – Memory T-cells

31. Activated T cell Activation leads to enlargement, differentiation and proliferation of T cells. T cells that are reproduced are clones of originally activated T cell. Activation, differentiation and proliferation occurs in secondary lymph organs and tissue. Activation leads to release of inflammatory cytokines.

32. Homeostatic imbalances : Immunodeficiencies Abnormally behaving immune cells Severe combined immunodeficiency (SCID) syndromes – Congenital conditions Acquired immune deficiency syndromes – Hodgkin’s Disease – HIV – AIDS

33. Homeostatic imbalances : Autoimmune disease – Tend to be more prevalent in women Type I diabetes—destroys pancreatic beta cells Multiple sclerosis—destroys myelin sheaths Myasthenia gravis—impairs communication between nerve and muscle Lupus erythematosus—systemic disease of skin, kidneys, heart, and lungs Rheumatoid arthritis—destruction of joints

34. Organ transplants Autografts—grafts from the same person to another body site Isografts—grafts between genetically identical individuals Allografts—grafts among the same species Xenografts—grafts taken from another animal species

35. Hypersensitivities Hypersensitivity Reactions in the Skin Hypersensitivity Reactions in the Skin

36. Hypersensitivities Acute Subacute Subacute Delayed Immediate cytotoxic Immune complex

37. Type I Hypersensitivity Type I Hypersensitivity Animation Type II Hypersensitivity

38. Type III Hypersensitivity

39. Animations Flash animation of a NK cell interacting with a normal body cell. Flash animation of a NK cell interacting with a normal body cell Flash animation of a NK cell interacting with a virus-infected cell or tumor cell not expressing MHC-I molecules. Flash animation of a NK cell interacting with a virus-infected cell or tumor cell not expressing MHC-I molecules Flash animation of apoptosis by NK cells. Flash animation of apoptosis by NK cells HIV Replication

40. Resources Components of the Immune System Animation Components of the Immune System Animation