Chapter 43 Reading Quiz

2. Chapter 43 Reading Quiz • Which group of cells make up 60 – 70% of all WBCs? • Prostaglandins & ____ are released by injured tissue to promote blood flow to the area. • The two main types of lymphocytes are the __ cells & the __ cells. • Which type(s) of blood could a Type B person receive?

3. 1. Describe the first non-specific line of defense the body has against infection. • The skin, mucous membranes, and secretions (saliva, tears) • Act as: 1. Physical barriers 2. Chemical defenses (sweat pH 3 – 5) - acidic stomach 

4. Lining of the trachea

5. 2. Describe the second non-specific line of defense, including the “killer cells”, inflammatory response, and antimicrobial proteins. • Phagocytic WBC’s (neutrophils) - engulf and destroy microbes - NK (natural killer) cells lyse infected cells • Inflammatory response - increase in local blood supply - histamine: triggers dilation (allergic reactions) - enhance migration of phagocytic cells • Antimicrobial proteins - interferons: limit cell to cell spread 

10. 3. What is the importance of specific immunity? What provides this specificity and diversity? • Lymphocytes provide the specificity and diversity of the immune system • B & T cells circulate throughout the blood & lymph - these recognize and respond to particular microbes and foreign molecules (antigens) • B cells secrete antibodies • With the diversity that exists, the immune system has the capacity to respond to millions of different antigenic molecules & pathogens 

11. 4. How are immune responses induced, and describe immunological memory. • Response induced when antigens interact with specific lymphocytes • Each selected lymphocyte is activated to divide & differentiate, forming 2 clones of cells A effector cells to combat antigen B  memory cells which bear receptors specific for that antigen for a long time - called “cloning selection” 

12. Immunological memory

14. 5. How does the immune system distinguish self from nonself? Why is this important? • T cells are developed in the thymus • B cells are developed in the bone marrow • As development occurs they are tested for self-reactivity - if positive, they become nonfunctional or a victim to apoptosis • Failure of self-tolerance can lead to autoimmune diseases like multiple sclerosis 

16. 6. Describe the various cell surface markers and their functions. • MHC  major histocompatibility complex - marks body cells as “self” - class I  found on all nucleated cells - class II  only macrophages, B & T cells - job is “antigen presentation”  present antigen proteins to T cells (2 types) 1. Cytotoxic T cells  antigen receptors bind to fragments (I MHC) 2. Helper T cells  bind to fragments from II MHC 

18. Humoral Immunity Involves B cell activation and results from the production of antibodies that circulate in the blood plasma & lymph Cell-mediated Immunity Depends on the action of T cells – immunity to some infections passed along when T lymphocytes are transferred  7. Describe humoral immunity and cell-mediated immunity.

20. 8. Overview the function of helper T lymphocytes in immunity. • II MHC molecules are recognized by helper T cells - serve as antigen-presenting cells • Help mobilize both humoral and cell-mediated branches of the immune response 

22. 9. How do cytotoxic T cells counter intracellular pathogens? Which response is this associated with? • Is associated with the cell-mediated response • The T cell receptor of a cytotoxic T cell recognizes a class I MHC antigen complex on the surface of an infected cell • Discharge of perforin protein, which lyses the antigen-presenting cell 

24. 10. Describe the process by which B cells make antibodies to fight against extracellular pathogens. Which response is this associated with? • Associated with the humoral response • Response is initiated when B cells bearing antigen receptors are selected by specific antigens - antibody initiated to known pathogen 

26. 11. Describe antibody structure and function. • Antibody molecule  2 identical antigen-binding sites, each molecule consists of four polypeptide chains (2 light, 2 heavy) 

27. 12. Describe the antibody-mediated disposal of antigen. • The binding of antibodies to antigens to form antigen-antibody complexes is the basis of several antigen disposal mechanisms • Ex: neutralization (blocks viral binding sites), agglutination, precipitation 

28. 13. Describe the immune system in invertebrates. • It is rudimentary and little is known • One well-developed aspect is the distinguishing between self and non-self • Have immunological memory 

29. 14. Describe the two ways in which immunity can be achieved. • Active  • Natural: depends on the response of the immune system • Artificial: immunization/vaccines (inactivated toxins) 2. Passive  • Antibodies transferred from one individual to another* • Pregnancy or injecting antibodies from other people 

30. 15. Why are blood transfusions and tissue transplants limited? Describe the problems associated with organ transplants. • The immune system’s capacity to distinguish self from nonself is what limits the possibilities • ABO blood groups, antigens, Rh factors • Graft vs. host reaction is due to the MHC (major histocompatibility complex) • The same mechanisms that help a body fight off invaders fights off the new transplant 

31. 16. Briefly discuss allergies. • Allergies are hypersensitive (exaggerated) responses to certain environmental antigens (allergens) • Most common allergies involve the antibodies of the IgE class (one of the 5 classes of Immunoglobins) • Most serious consequence is anaphylactic shock - drop in blood pressure and death - must carry a syringe with epinephrine - common  bee venom, penicillin, peanuts, fish 

33. 17. What are autoimmune diseases? • When the immune system loses tolerance for self and turns against certain molecules of the body • Ex: lupus  antibodies generated against all molecules • Ex: rheumatoid arthritis  cartilage and joints are damaged • Ex: multiple sclerosis  T cells reactive against myelin sheath in nervous system 

36. 18. What are immunodeficiency diseases? • It is an immune dysfunction • Mostly genetic, the worst is SCID (severe combined immunodeficiency) where both branches of the immune system fail • Must have a bone marrow transplant • Ex: Hodgkin’s disease, suppresses the lymphatic system 

37. 19. Describe AIDS and the history and treatment of this disease. • In 1981, a particular type of sarcoma (cancer of skin & blood vessels) was noticed  rare except in immunosuppressed individuals • AIDS  acquired immuno-deficiency syndrome - susceptible to opportunistic diseases, infections, and cancers • In 1983, HIV (retrovirus human immunodeficiency virus) was identified as the causative agent of AIDS 

42. AIDS continued… • Mortality is about 100%, it is the most lethal pathogen ever encountered • Probably evolved from an HIV-like virus (SIV) in Africa • Seen as early as 1959 in blood samples • AIDS cannot be cured at this time and the progression of HIV  AIDS cannot be stopped • Treatment is very expensive and includes: 1. DNA inhibitors 2. Reverse transcriptase inhibitors 3. Protease inhibitors • HIV is transmitted via infected body fluids (blood/semen); is NOT contracted by casual contact • In 1997, 6 million people acquired HIV 