Chapter 43 Reading Quiz 1.Which group of cells make up 60 – 70% of all WBCs? 2.Prostaglandins & ____ are released by injured tissue to promote blood flow to the area. 3.The two main types of lymphocytes are the __ cells & the __ cells. 4.Which type(s) of blood could a Type B person receive?

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

Lining of the trachea

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

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

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”

Immunological memory

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

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

7. Describe humoral immunity and cell- mediated immunity. 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

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

9. How do cytotoxic T cells counter intracellular pathogens? Which response is this associated with? Is associated with the cell-mediated response 1.The T cell receptor of a cytotoxic T cell recognizes a class I MHC antigen complex on the surface of an infected cell 2.Discharge of perforin protein, which lyses the antigen-presenting cell

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

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

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

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

14. Describe the two ways in which immunity can be achieved. 1.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

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

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

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 

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 

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 

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 