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THE IMMUNE SYSTEM AND MECHANISMS OF DEFENSE

THE IMMUNE SYSTEM AND MECHANISMS OF DEFENSE. Chapter 13. Pathogens can cause damage to our bodies by. releasing harmful enzymes or toxins. causing our cells to rupture. using up our body’s resources. Types of Pathogens. Bacteria. Characteristics: Prokaryotic Single celled

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THE IMMUNE SYSTEM AND MECHANISMS OF DEFENSE

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  1. THE IMMUNE SYSTEM AND MECHANISMS OF DEFENSE Chapter 13

  2. Pathogens can cause damage to our bodies by • releasing harmful enzymes or toxins. • causing our cells to rupture. • using up our body’s resources.

  3. Types of Pathogens

  4. Bacteria • Characteristics: • Prokaryotic • Single celled • Use of variety of resources for growth and reproduction

  5. Bacterial Infections: • Pneumonia • tonsillitis • tuberculosis • botulism • syphilis • Lyme disease

  6. Viruses • Characteristics • Extremely small • Non-Living?

  7. Viral Infections • AIDS • hepatitis • rabies • colds • warts • chicken pox

  8. Determination of Health Risk • Transmissibility: • how easily passed from person to person • Mode of transmission: • respiratory, fecal–oral, body fluids • Virulence: • how much damage caused by infection

  9. Lymphatic System: Functions • Maintenance of blood volume in cardiovascular system • Transport of fats and fat-soluble material from digestive system • Filtration of foreign material to defend against infection

  10. Lymphatic System: Components • Lymph • protein-containing fluid transported by lymphatic vessels • Lymph nodes • cleanse lymph by filtering out material • Spleen • cleanses blood, removes dying red blood cells, helps fight infection

  11. Thymus • secretes thymosin and thymopoietin to cause T lymphocytes to mature • Tonsils • protect throat

  12. SECTION ASSIGNMENT  Due at the end of class USE THE TEXTBOOK

  13. Physical and Chemical Barriers

  14. First Line of Defense • Provides physical and chemical barriers: • Skin: characteristics of barrier • Structure: dead layer, inhospitable to microorganisms • Constant replacement: many adhering microorganisms removed • pH = 5–6: too acidic for many microorganisms

  15. First Line of Defense • Other: • tears • saliva • earwax • digestive acids • mucus • vomiting

  16. Nonspecific Defenses: Second Line

  17. Nonspecific Defenses: Second Line • Phagocytosis • by neutrophils, macrophages, eosinophils • Inflammatory response • Signs: redness, warmth, swelling, pain

  18. Inflammatory Response Process: • tissue damage leads to release of histamine, • blood vessels dilate, • complement marks bacteria, • phagocytic cells arrive and remove invading microorganisms

  19. The Inflammatory Response Figure 9.7

  20. Lines of Defense: Second Line • Natural killer cells: lymphocytes • Complement system: group of plasma proteins • Interferons: interfere with virus spread • Fever: increases host cell defenses and metabolic activity

  21. Cells & Proteins Involved in Specific Defenses

  22. Specific Defense Mechanism: Third Line • Immune response • Antigens: major histocompatibility complex (MHC) proteins • B cells: antibody-mediated immunity, action by antibodies: • Classes of antibodies • Examples – IgG, IgM, IgA, IgE

  23. Line of Defense: Third Line • T cells • cell-mediated immunity, action by cells • Helper T cells • stimulate other immune cells • Cytotoxic T cells • kill abnormal and foreign cells • Memory T cells • reactivate on re-exposure • Suppressor T cells • suppress other immune cells

  24. The Basis of Immunity Due to memory cells

  25. Immune Memory Creates Immunity:Primary Immune Response • Process: • recognition of antigen, production and proliferation of B and T cells • Characteristics: • lag time of 3–6 days for antibody production, peak at 10–12 days

  26. Immune Memory Creates Immunity:Secondary Immune Response • Process • recognition of antigen, production and proliferation of T cells and plasma cells • Characteristics • lag time in a few hours, peak in days

  27. Medical Assistance in the War Against Pathogens • Active immunization • effective against viruses • Antibiotics • effective only against bacteria, resistance a problem

  28. Inappropriate Immune Responses • Allergies • hypersensitivity reaction, excessive inflammatory response mediated by IgE • Types of allergic responses • Localized: affect only the area exposed • Systemic: affect several organ systems

  29. Anaphylactic shock: severe systemic allergic reaction • Symptoms: • difficulty breathing • severe stomach cramps • swelling throughout the body • circulatory collapse • drop in blood pressure

  30. Inappropriate Immune Responses:Autoimmune Disorders • Defective recognition of “self” • Lupus erythymatosis (LE or lupus): • inflamed connective tissue • Rheumatoid arthritis: • inflamed synovial membrane

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