Memmler’s The Human Body in Health and Disease 11 th edition

1. Memmler’s The Human Body in Health and Disease11th edition Chapter 17 Body Defenses, Immunity, and Vaccines

2. The Immune System • Types of general body defenses against disease • Nonspecific defenses • Effective against any harmful agent • present from birth; do not distinguish one type of threat from another • Specific defenses • Effective against a certain agent only • Depend on specific lymphocyte activities • Produce state of protection (immunity or specific resistance)

3. Why Do Infections Occur? • Factors involved in infection • Portal of entry • Virulence of organism • Aggressiveness • Toxin production • Dose (number) of pathogens • Individual condition (predisposition) to infection

4. Nonspecific Defenses Physical barriers Phagocytes NK Cells (immunological surveillance) Inflammatory response Fever Interferons Complement

5. Chemical and Mechanical Barriers • Skin • Mucous membranes • Cilia • Body secretions • Tears • Perspiration • Saliva • Digestive juices • Reflexes • Sneezing • Coughing • Vomiting • Diarrhea

6. Phagocytes Engulf and destroy foreign compounds and pathogens “First line of cellular defense” against pathogenic invasion Types Neutrophils (in bloodstream and tissues) Phagocytize cellular debris or bacteria Eosinophils (less abundant) Phagocytize foreign compounds and antibody-coated pathogens Macrophages (derived from monocytes) Fixed (permanent residents of certain organs) Free (travel throughout body)

8. Natural Killer Cells Type of lymphocyte • Can recognize body cells with abnormal membranes • Found in lymph nodes, spleen, bone marrow, blood • Secrete protein that breaks down cell membrane

9. Immunological Surveillance Constant monitoring of normal tissues by NK cells Normal cells are generally ignored by immune system Cancer cells often contain tumor-specific antigens NK cells recognize as abnormal and destroy NK cells recognize bacteria, foreign cells, virus-infected cells, and cancer cells

10. NK cells recognize and kill target cells Step 2: The Golgi apparatus moves around the nucleus until the maturing face points directly toward the abnormal cell. A flood of secretory vesicles is then produced at the Golgi apparatus. These vesicles, which contain proteins called perforins, travel through the cytoplasm toward the cell surface. Step 3: The perforins are released at the cell surface by exocytosis and diffuse across the narrow gap separating the NK cell from its target. Step 4: As a result of the pores made of perforin molecules, the target cell can no longer maintain its internal environment, and it quickly disintegrates. Step 1: If a cell has unusual components in its plasma membrane, an NK cell recognizes that other cell as abnormal. Such recognition activates the NK cell, which then adheres to its target cell. Golgi apparatus Abnormal cell NK cell Perforin molecules Pores produced by the interaction of perforin molecules NK cell Abnormal cell

11. Immunological Surveillance, cont’d NK cells also destroy abnormal cells Abnormal daughter cells occur during cell division Some abnormal cells become cancer cells

12. NK cells detect and destroy abnormal cells resulting from faulty cell division NK cell identifies and destroys abnormal cell Abnormal cell Stem cell Daughter cells Daughter cells

13. Inflammation Infection is inflammation caused by pathogens • Inflammatory reaction (response) • Heat, redness, swelling, pain • Cells release histamine • Leukocytes enter tissue • Granulocytes, macrophages, mast cells • Leukocytes and plasma produce inflammatory exudate • Pus is produced • Lymph nodes enlarge

14. The Events in Inflammation Tissue damage causes chemical change in interstitial fluid Mast cell activation Release of histamine and heparin Causes: Increased blood flow to area Clot formation Phagocyte attraction (removes debris and activates specific defenses) Tissue repair Pathogen removal, clot erosion, scar tissue formation

15. Fever As phagocytes work, they release substances that raise body temperature • Pyrogens • Reset temperature thermostat in hypothalamus • Stimulates phagocytes • Increases metabolic rate which may accelerate tissue defenses and repair process • Decreases some organisms’ ability to multiply

16. Interferons Small proteins released by activated lymphocytes, macrophages, and virus-infected tissues Trigger antiviral proteins in cytoplasm of nearby cells Do not prevent entry of viruses but interfere with viral replication Also stimulate activities of macrophages and NK cells

17. Interferons, cont’d Three types Alpha (α) interferons (produced by virus-infected cells) Attract and stimulate NK cells and give viral resistance Beta (β) interferons (secreted by fibroblasts) Slow inflammation in damaged area Gamma (γ) interferons (secreted by T cells and NK cells) Stimulate macrophage activity

18. Three Types of Interferons Alpha (α)-interferons are produced by cells infected with viruses. They attract and stimulate NK cells and enhance resistance to viral infection. Beta (β)-interferons, secreted by fibroblasts, slow inflammation in a damaged area. Gamma ()-interferons, secreted by T cells and NK cells, stimulate macrophage activity.

19. Complement System Complement system (complementsantibody action) 11 plasma proteins that interact to attach to foreign cells Pore formation formed by many complement proteins Destroys integrity of target cell

20. Complement System Enhanced phagocytosis Attracts phagocytes and makes target cells easier to engulf = Opsonization Histamine release By mast cells and basophils Increases inflammation and blood flow to region

21. Summary of the Body’s Nonspecific Defenses Physical Barriers Prevent approach of and deny access to pathogens Secretions Epithelium Duct of eccrine sweat gland Hair Phagocytes Remove debris and pathogens Fixed macrophage Free macrophage Neutrophil Eosinophil Monocyte Immunological Surveillance Destroys abnormal cells Lysed abnormal cell Natural killer cell Interferons Increase resistance of cells to viral infection; slow the spread of disease Interferons released by activated lymphocytes, macrophages, or virus-infected cells

22. Summary of the Body’s Nonspecific Defenses Complement System Attacks and breaks down the surfaces of cells, bacteria, and viruses; attracts phagocytes; stimulates inflammation Lysed pathogen Complement Inflammatory Response • Blood flow increased • Phagocytes activated • Damaged area isolated by clotting reaction • Capillary permeability increased • Complement activated • Regional temperature increased • Specific defenses activated Multiple effects Mast cell Fever Mobilizes defenses; accelerates repairs; inhibits pathogens Body temperature rises above 37.2°C in response to pyrogens

23. Immunity • Power to overcome a specific disease agent • Innate immunity • Inherited in genes • Adaptive immunity • Develops after birth • Acquired naturally or artificially • Active or passive

24. Types of immunity

25. Innate Immunity Differences in physical constitution • Species immunity • Individual immunity

26. Adaptive Immunity Develops in a person • During lifetime • From encounters with specific harmful agents

27. Antigens • Foreign substances that • Enter body • Induce immune response of certain lymphocytes • T cells • B cells

28. T Cells • Originate in stem cells in bone marrow • Change to T cells in thymus • Become sensitized to specific antigens • Produce cell-mediated immunity • Cytoxic T cells • Helper T cells • Regulatory T cells • Memory T cells • Macrophages

29. Activation of a helper T cell by a macrophage (antigen-presenting cell).  Zooming In: What is contained in the lysosome that joins the phagocytic vesicle?

30. B Cells and Antibodies Antibody (Ab) also known as immunoglobulin (Ig) is substance produced in response to antigen • Manufactured by B cells (B lymphocytes) • Must mature in fetal liver or in lymphoid tissue • Provides humoral immunity • Contained in gamma globulin fraction of blood plasma

31. Activation of B cells. The B cell combines with a specific antigen. The cell divides to form plasma cells, which produce antibodies. Some of the cells develop into memory cells, which protect against reinfection.   • Zooming In: What two types of cells develop from activated B cells?

32. The Antigen–Antibody Reaction Complement is the enzymatic activity of a group of nonspecific proteins in blood that: • Coats foreign cells • Destroys cells • Promotes inflammation • Attracts phagocytes

33. Naturally Adaptive Immunity Immunity acquired through contact with a specific disease organism • Active immunity • Passive immunity

34. Artificially Adaptive Immunity Vaccination (immunization) can cause a person’s immune system to manufacture antibodies • Preventive measure • Risk of side effects

35. Types of Vaccines • Live • Attenuated • Toxoid • Killed by heat or chemicals • Antigenic component • Genetically engineered

36. Boosters • Active immunity does not always last a lifetime • Repeated inoculations (booster shots) help maintain high titer of antibodies in the blood • Number and timing varies with vaccines

37. Examples of Vaccines • Whooping cough (pertussis) • Diphtheria, tetanus toxoid (Td) • Haemophilus influenzae type B (Hib) • Pneumococcal vaccine (PCV) • Viral • Inactivated polio, oral polio • Measles (rubeola), mumps, rubella (MMR) • Hepatitis B • Hepatitis A • Chicken pox (varicella); vaccine for shingles now available for those >60 yr • Influenza • Rabies • Rotavirus • HPV (human papillomavirus) for girls 11-26

38. Passive Immunity Acquired by administration of immune serum (antiserum) • Short-lived immunity • Used in emergencies • Often derived from animals • May cause sensitivity reaction

39. Disorders of the ImmuneSystem • Resulting from overactivity • Allergy • Autoimmune disease • Resulting from underactivity • Hereditary • Infections • Environmental

40. Allergy Abnormal reactivity to one’s own tissues • Factors • Disease • Loss of immune system control • Cross-reaction of antibodies and self antigens • Treatments • Immune-suppressing drugs • Chemotherapy/stem cell replacement

41. Immune Deficiency Diseases Failure of immune system • May involve any part of system • Varies in severity • Congenital or acquired (e.g., AIDS) • HIV • A retrovirus; uses reverse transcriptase enzyme

42. Multiple Myeloma Cancer of blood-forming bone marrow cells • Effects of disease • Lowered resistance to infection • Anemia • Bone pain • Bone tissue loss • Kidney failure • Treatment • Chemotherapy • Bone marrow transplants

43. The Immune System and Cancer • Immune surveillance • Declines with age • Immunotherapy • T cells activated with interleukin • Vaccines

44. Transplantation and Rejection Syndrome • Caused by normal antigen–antibody reaction • Reduced by • Tissue typing • Immune suppression drugs

45. End of Presentation