64) What is occuring when an antibody renders bacterial toxins, viral proteins, or animal venom inactive? A) complement activation B) opsonization C) neutralization D) agglutination Answer: C 65) Which of the following is NOT a function of antibodies? A) phagocytosis B) opsonization C) neutralization D) agglutination Answer: A 66) Which immune response has a shorter lag phase in which more antibody levels peak more rapidly? A) inflammation response B) secondary immune response C) passive immunity D) primary immune response Answer: B 67) The primary immune response: A) occurs after the first exposure to an antigen. B) has a shorter lag phase than the secondary immune response. C) primarily involves the antibody IgG. D) produces peak antibody levels rapidly (1-3 days). Answer: A 68) Vaccinations involve exposure to an antigen to elicit: A) passive immunity. B) a primary immune response. C) severe allergic reaction. D) a secondary immune response. Answer: B 69) What of the following confers passive immunity? A) antivenin against snake venom B) viral infection C) vaccination D) bacterial infection Answer: A 70) What type of cell is activated in lymphatic tissue by macrophages presenting antigens during a viral infection? A) natural killer (NK) cell B) helper T (TH) cell C) plasma cell D) memory B cell Answer: B 71) What cells play an extensive role in the eradication of bacteria as phagocytes? A) basophils B) neutrophils C) memory B cells D) eosinophils Answer: B 72) Elevated levels of neutrophils indicate: A) bacterial infection. B) viral infection. C) cancer. D) normal condition. Answer: A 73) T cells and natural killer (NK) cells are largely involved in scanning the cells in the body for tumor antigens, a function known as: A) immune surveillance. B) complement. C) agglutination. D) vaccination. Answer: A 74) Cancer cells can suppress T cell activity by releasing: A) cytokines. B) perforins. C) pyrogens. D) opsonins. Answer: A 75) Type I, or immediate, hypersensitivity triggers plasma cells to secrete: A) IgM B) IgD C) IgE D) IgA Answer: C 76) Blood transfusions between incompatible blood types results in: A) type I, or immediate, hypersensitivity. B) type II, or antibody-mediated, hypersensitivity. C) type III, or immune-complex mediated, hypersensitivity. D) type IV, or delayed-type, hypersensitivity. Answer: B 77) Failure of the thymus to develop, low circulating levels of lymphocytes, and failure of cellmediated immunity characterize: A) severe-combined immunodeficiency (SCID). B) antibody-mediated hypersensitivity. C) acquired immunodeficiency syndrome (AIDS). D) human immunodeficiency virus 1 (HIV-1). Answer: A 78) What cells decline in number during the final phase of HIV-1 infection, when an individual is said to have AIDS? A) memory B cells B) B cells C) plasma cells D) helper T (TH) cells Answer: D 79) When a person has an autoimmune disorder, antibodies are secreted that bind to: A) immunoglobulins. B) other antibodies. C) self antigens. D) allergens. Answer: C 80) The cisterna chyli collects lymph from the intestinal trunk and the lumbar trunk. Answer: TRUE 81) Lymph capillaries form a two-way system that moves lymph to and from the heart. Answer: FALSE 82) The framework of the spleen is created by a network of reticular fibers made by reticular cells. Answer: TRUE 83) Adaptive, or specific, immunity consists of antimicrobial proteins and certain cells that respond quickly to pathogens within the first 12 hours after exposure. Answer: FALSE 84) Immunological memory can be formed by exposure to an antigen which is remembered by specific leukocytes and circulating antibodies. Answer: TRUE 85) Surface barriers, such as the cutaneous and mucous membranes, provide innate immunity against pathogens. Answer: FALSE 86) Membrane-attack complexes (MAC) can lead to cell lysis through their insertion into a target cell's plasma membrane. Answer: TRUE 87) Pus indicates only that an inflammatory response took place. Answer: TRUE 88) A patient with a body temperature of 38° C (or 99° F) is said to have a fever. Answer: FALSE 89) Self antigens usually generate an immune response in our own bodies. Answer: FALSE 90) T cells directly interact with antigens without other cells involved. Answer: FALSE 91) B cell proliferation occurs when an antigen binds to a B-cell receptor on the surface of a specific B-cell clone. Answer: FALSE 92) IgM is the first antibody secreted by plasma cells when the body is invaded by a pathogen. Answer: TRUE 93) A lack of memory cells mainly affects the primary immune response. Answer: FALSE 94) Vaccinations elicit a primary immune response so that secondary immune responses are rapid and symptoms are mild. Answer: TRUE 95) Bacterial infections and viral infections progress through an identical sequence of events during the immune response. Answer: FALSE 96) Immunodeficiency disorders can result from a failure of one component of the immune system. Answer: TRUE Match each antibody with its correct description. A) IgG B) IgD C) IgA D) IgM E) IgE 97) Found in secretions such as breast milk and saliva 98) The only antibody that can cross the placenta from mother to fetus 99) The first antibody secreted upon exposure to an antigen 100) The only antibody not secreted in significant amounts by B cells 101) Binds antigens associated with parasitic pathogens and allergens Answers: 97) C 98) A 99) D 100) B 101) E Match the following with the lymphoid tissue or organ. 102) Identify the mucosa-associated lymphatic tissue (MALT) associated with the gastrointestinal tract. Answer: E 103) Locate the organ that produces populations of T cells during infancy and childhood. Answer: B 104) Locate the lymphoid organ that filters pathogens from blood. Answer: D 105) Identify the tonsils. Answer: A 106) Locate the lymphoid organ that filters pathogens from lymph. Answer: C 107) Describe the functions of the lymphatic system. Answer: The lymphatic system has several functions. First, the lymphatic system regulates interstitial fluid volume by returning fluids escaped from the cardiovascular system to circulation. Second, dietary fats are absorbed into specialized lymphatic vessels in the small intestine. And, last, the lymphatic system plays a role in immune function by filtering pathogens from lymph and the blood. Several types of leukocytes are housed in lymphoid organs, which play a role in their maturation. 108) Explain how lymph is formed. Answer: Net filtration pressure in blood capillaries favors filtration, meaning that water is lost from the plasma in the blood to the interstitial fluid. Excess interstitial fluid must be returned to circulation to maintain blood volume and blood pressure. Once the fluid exits the interstitial space and enters the lymphatic vessels, it is now known as lymph. 109) Discuss the significance of the extreme permeability of lymphatic capillaries. Answer: The extreme permeability of lymphatic capillaries allows large volumes of fluid to enter from the interstitial space. When pressure in the interstitial fluid decreases, the endothelial cells of the lymphatic capillaries flap shut. In this way, the lymphatic system plays the crucial role of precisely controlling the amount of fluid between our cells. Also, pathogens such as bacteria and cancer cells in the interstitial fluid have an easier time entering the lymphatic capillaries than the blood capillaries due to their extreme permeability. The spread of these pathogens throughout the body can be limited by lymph nodes, which act as filters by trapping pathogens and preventing them from traveling elsewhere. 110) Mr. Hartsell, a 70-year-old man, had his thymus gland removed as a treatment for an autoimmune disease he has. Predict the effect of his thymectomy on T cell production. Answer: We would not expect to see a decline in immune function in a 70-year-old man due to the enormous number of immunocompetent T cells produced during infancy and childhood. The thymus is very active in infants and children and reaches its maximum size in individuals about 12-14 years old. After this point, it begins to atrophy and the thymic tissue is gradually replaced with fat. As the thymus atrophies, its production of mature T cells decreases as well. Indeed, by age 65, the rate of T cell production falls to about 2% of the rate at which an infant produces T cells. So, although new mature T cell production would cease, it is already very low at his age and so would likely have little overall effect. 111) Discuss the two different types of immunity. Answer: The two types of immunity are innate, or nonspecific, immunity and adaptive, or specific, immunity. First, innate immune system consists of antimicrobial proteins and certain cells. Innate immunity responds quickly and is the dominant response to pathogens for the first 12 hours after exposure due to readily available cells and proteins in the bloodstream. The second type of immunity, known as adaptive or specific immunity, includes components that respond to specific antigens. Adaptive immunity responds more slowly than innate immunity because one must be exposed to a specific antigen for the response to be initiated. 112) Summarize the surface barriers that provide a first line of defense against pathogens. Answer: Cutaneous membranes and mucous membranes provide a continuous physical barrier to block the entry of potential pathogens into the body. Skin is relatively resistant to mechanical stress due to several layers of cells filled with keratin. Oil, or sebum, has a slightly acidic pH that deters the growth of most pathogenic organisms and is produced by sebaceous glands in the skin. Mucous membranes also secrete products that discourage pathogen invasion such as mucus or stomach acid. 113) Determine why long-acting interferon medications are often prescribed for viral infections, such as hepatitis C. Answer: Interferon medications can prolong the effects of interferons and help prevent the spread of viral infections, such as hepatitis C. Interferons are generally produced in response to infection with intracellular agents such as viruses or intracellular bacteria, and are named for their ability to "interfere" with the ability of the pathogens to infect other cells. One of the primary actions of interferons is to inhibit viral replication inside host cells. 114) List the cardinal signs of inflammation. Answer: The cardinal signs of inflammation are redness, heat, swelling (edema), and pain. 115) Discuss the contribution of vasodilation to the inflammatory response. Answer: Vasodilation involves inflammatory mediators such as histamine and bradykinin. These vasodilators relax the smooth muscle in arterioles supplying damaged tissue, causing the vessels to "open up" and blood to flow through them more freely. As a result, blood flow to the damaged tissue increases. 116) Explain the role of monocytes in the inflammatory response. Answer: Monocytes are involved in the second component of the inflammatory response. Circulating monocytes exit the blood by diapedesis. When they arrive at the damaged tissue, they enlarge and mature into macrophages, a response that takes several hours. As macrophages, pathogens and damaged cells are phagocytized in greater numbers than in the initial phase of neutrophil response. 117) Determine for what condition Jourdan should take an antipyretic medication. Answer: Antipyretics would be taken for fever since they reduce inflammation-mediated fever by resetting the hypothalamus back to the normal temperature range. Antipyretics inhibit the formation of prostaglandins. 118) Explain the role of major histocompatibility complex (MHC) molecules in T cell activation. Answer: T cell activation begins with a cell processing and displaying antigen fragments on its MHC molecules. It then presents the antigen to a particular T cell clone, which is specific for its individual MHC-antigen complex. When the T cell receptor recognizes and binds this complex, multiple changes are triggered inside the T cell and the process of activation begins. This process is known as clonal selection because the antigen "selects" a particular T cell clone. Full T cell activation requires the interaction of the T cell with other molecules on the cells called costimulators. 119) Discuss immunological memory and the role of T cells in its formation. Answer: Activated helper T (TH) cells or cytotoxic T (TC) cells can differentiate either into effector cells or memory T cells. Memory T cells are responsible for immunological memory, in which these cells respond more quickly and efficiently to subsequent exposures to an antigen. Memory T cells need no co-stimulator, so the response is considerably more rapid. 120) Explain the role of major histocompatibility complex (MHC) molecules and human leukocyte antigen (HLA) genes in organ transplant and rejection. Answer: Compatibility between organ donor and organ recipient is determined through a process that screens the antigens most likely to cause rejection–those associated with MHC molecules, which are encoded on genes called human leukocyte antigen (HLA) genes. A donor individual who has a high percentage of HLA similarity to the recipient is said to be a match. Exact HLA matches are rare and most likely to be found within families. 121) List the five major classes of antibodies. Answer: The five major classes of antibodies are IgA, IgD, IgE, IgG, and IgM. 122) Clark received a vaccine to help protect him against the measles, but his childhood friend Nicole contracted the measles since she did not receive a vaccine. For each person, determine if active immunity or passive immunity is involved and explain why Clark benefitted from the vaccine. Answer: Both Clark and Nicole received active immunity through their contact with the measles virus. Active immunity may be received naturally through exposure to an antigen via infection or artificially via a vaccination. It results in the production of memory cells and large numbers of antibodies and is, therefore, relatively long-lasting, ranging from years to a lifetime. The benefit for Clark is he did not have to experience the disease to form immunological memory against it. 123) Explain immune surveillance. Answer: T cells and natural killer (NK) cells "scan" the cells in the body for tumor antigens, a function known as immune surveillance. Immune surveillance is absolutely critical to the prevention of tumor development. 124) Explain how a type I, or immediate, hypersensitivity is different from a typical primary immune response. Answer: Type I, or immediate, hypersensitivity reactions occur when an individual reacts to a foreign antigen, an allergen. In the first exposure of an individual to an allergen, (1) an allergen binds a B cell, and (2) the B cell differentiates into plasma cells that begin to secrete antibodies, just as they normally would when exposed to a foreign antigen. But there is one key difference between this response and a normal response: The plasma cells secrete IgE instead of IgG or IgM. This first exposure generates a primary immune response, which occurs slowly and produces few symptoms, but does result in the formation of large numbers of IgE molecules that coat mast cells and basophils. Subsequent exposures to the allergen in a sensitized person result in rapid responses that occur within a few minutes. 125) Explain how mucosa-associated lymphatic tissues (MALT) complement the function of the lymph nodes in the lymphatic system. Answer: Mucosa-associated lymphatic tissues (MALT) are loosely organized clusters of lymphoid tissue that protect the body from pathogens, found scattered throughout the gastrointestinal tract, the respiratory passages, including the oral and nasal cavities, and, to a limited extent, the genitourinary tract. Lymph nodes are small clusters of lymphatic tissue scattered loosely along lymphatic vessels throughout the body that limit the spread of pathogens through the body by acting as filters, trapping pathogens traveling in lymph and preventing them from traveling elsewhere. Both MALT and lymph nodes play an important role in immunity by protecting the body from pathogens. 126) Gary, who is sick with a cold, sneezed on you during lunch. Determine which line of defense provides initial protection for you. Answer: The first line of defense, which includes surface barriers, protects you initially. Your skin and mucosae are surface barriers and provide a continuous physical block to entry of pathogens into the body. Keratin, oil (sebum), and mucus prevent invasion by pathogens. 127) Determine why antihistamine medications can be effective treatments against the inflammatory response. Answer: Antihistamines block the effects of histamine and reduces inflammation and swelling of damaged tissues. Histamine, a type of inflammatory mediator that is a potent vasodilator, relaxes the smooth muscle in arterioles supplying damaged tissue. Histamine causes vessels to "open up" and blood to flow through them more freely. This results in increased blood flow to the damaged tissue, and the area becomes congested with blood. 128) Explain how T cell activation, proliferation, and differentiation are affected if a costimulator is unavailable. Answer: Full T cell activation requires the interaction of the T cell with other molecules on the cells called co-stimulators. Without activation, TH or TC cells would not increase in number, nor would they differentiate into effector cells, those that cause the immediate effects, or memory T cells, those cells that provide cell-mediated immunological memory. 129) Determine the type of tissue grafts that would be most unlikely to experience rejection and explain why. Answer: Two types of graphs would be least likely to trigger rejection: autografts and isografts. Autografts involve tissue transplanted from one site to another in the same individual. Examples of autografts include skin grafts, in which skin is removed from one part of the body and placed on another part to repair skin damaged by trauma such as burns. Isografts involve organs and tissues transplanted between two genetically identical individuals. These are relatively uncommon due to the small number of identical twins. Autografts and isografts result in no response from TC cells because the antigens bound to class I MHC molecules are not recognized as foreign. 130) Bill first had the influenza vaccine in October. He experienced a headache, achiness, fatigue, and a fever. When he came into contact with the influenza virus a few months later, he hardly had any symptoms at all. Explain these two different immune responses seen with each exposure to the virus. Answer: The primary immune response began with Bill's first exposure to the influenza virus. His B cells were activated and proliferated into plasma cells, which secreted antibodies, and memory B cells. This initial lag phase is slow as B cells proliferate over 4-5 days, with antibody production peaking 7-14 days after the first encounter with the antigen. The next time Bill was exposed to the same antigen, the response was much different since the memory B cells formed during the primary immune response are long-lived. When these memory B cells encounter the antigen for which they are specific, the secondary immune response began. The secondary immune response has a shorter lag phase (about 1-3 days), and its antibody levels peak more rapidly (3-5 days) and reach a peak 100-1000 times larger. For this reason, he had mild symptoms when exposed to the same antigen for the second time.