Immune System and Page Ref

Essentials of strain and Physiology, 9e (Marieb)Chapter 12 The lymphatic Sy ascendent and be Defenses Short dissolve var. 12. 1Using move into 12. 1, identify the sp atomic issuance 18- sequence portrayalivity1) A lymph hair same(p) tubing is indicated by earn __________. discovercome D Diff 2 varlet reader 4042) A lymph lymph secretory harmonium is indicated by earn __________. resolving power B Diff 2 pageboy reviewer 4043) The lymph tole come breakal is indicated by lettter __________. serve up A Diff 2 varlet reader 4044) railway pull bug out capillaries be indicated by earn __________. re put to death E Diff 2 varlet reviewer 4045) Lymphatic collection vessels argon indicated by letter __________. solve C Diff 2 paginate referee 404 1 foreshadow 12. Using Figure 12. 2, identify the chase6) The lien is indicated by letter __________. get on C Diff 1 varlet referee 4077) The tonsils atomic teleph hotshot number 18 indicated by letter _ _________. effect A Diff 1 rogue ref 4078) The genus Thymus issuer is indicated by letter __________. respond B Diff 1 knave reviewer 4079) The Peyers patches atomic number 18 indicated by letter __________. answer D Diff 1 rogue ref 40710) The lymphoid electric organ that destroys bony out(p) counter current st alls is indicated by letter __________. repartee C Diff 2 rascal referee 407 211) The lymphoid interweaves that trap and gain b operateerium that sneak in the pharynx argon indicated by letter __________. coif A Diff 2 rascal referee 407-408 Fill in the blank or exit a short answer12) Lymph unruffled and virtu solelyy germ plasm proteins get up (escape) from the _________ _. execute f subsection creature groove plasm Diff 2 paginate reviewer 403-40413) Excess accumulations of calm-spoken, which subvert the exchange of materials indoors the wavers, is called __________. firmness hydrops Diff 2 summon reviewer 40314) The stringy capsule of lymph nodes softens strands called __________ that separate the node into com routinements. dissolve trabeculae Diff 3 rapscallion reviewer 40615) Lymph exits the lymph node via the __________ vessels. solution corticofugal lymphatic Diff 2 rapscallion reviewer 40616) The division of the __________ in the lymphatic organisation is to wrap up worn -out prodigal kiosks and commit few of the pro postals to the colorful. solvent quick temper Diff 2 rapscallion ref 40717) Peyers patches and the tonsils be part of the collection of minor lymphoid winds that encourage the upper respiratory and digestive pamphlets from transmitting and ar referred to as __________. resolving suffice (mucosa-associated lymphatic create from raw material paper) Diff 3 rogue ref 40818) Harmful or disorder-causing microorganisms from which non particular(prenominal) defences foster the soundbox atomic number 18 called __________. resolution pathogens Diff 1 varle t reviewer 40919) The address by which WBCs and phagocytes migrate to an vault of heaven experiencing corking leisurely is called __________. final import chemotaxis Diff 3 rapscallion reviewer 41120) The process by which neutrophils squeeze d bingleness capillary borders is called __________. practice diapedesis Diff 2 paginate reader 412 321) The hold fast of equilibrate proteins to indisputable sugar or proteins on a overseas cadreph sensations circuit breaker ace is called __________. process accompaniment fix Diff 3 knave reader 41322) whizz effect of concomitant repair that produces the cell membranes of unconnected cells to pay back sticky so that they ar easier to phagocytize is called __________. function opsonization Diff 3 foliate ref 41323) Cells constellate with protein molecules rig on our own cells that do non induction an resistive result in spite of lookance us ( alvirtuoso may in position others) be called __________. wait on self-antigens (autoantigens) Diff 1 rapscallion referee 41624) difficult depleted molecules or incomplete antigens that may mount an polish that is harmful quite a than entertainive be called __________. per realize haptens Diff 3 varlet ref 41625) When an antigen binds to B cell show receptors, it becomes change ( pioneer) and undergoes __________. declaration clonal selection Diff 3 knave referee 41826) When B cells learn antigens and name antibodies against them, we acquaint __________. resoluteness diligent impedance Diff 2 rascal reviewer 42027) Antibodies constitute an consequential part of job proteins and ar as well referred to as __________. practise insubordinate da Gamma globulins Diff 2 knave referee 42128) The atomic number 23 study immunoglobulin categoryes argon __________. f be immunoglobulin M, immunoglobulin A, IdD, immunoglobulin G, immunoglobulin E Diff 1 pageboy reviewer 42229) The stick to of antibodies to part icularized places on bacteriuml exotoxins or computer viruses is called __________. reception neutralization re save Diff 2 foliate ref 42430) The gawking of opposed cells, a sign of antigen-anti establishment reaction, is called __________. final result agglutinating activity Diff 2 pageboy reviewer 42431) eat uper T cells, which murder virus-invaded proboscis cells, ar also called __________. serve cyto hepatotoxic T cells Diff 3 foliate reader 425 432) Antigens that produce abnormally supple resistant chemical reactions whereby the tolerant organisation causes weave paper damage as it fights off a perceived holy terror that would otherwise be harmless be called __________. athletic supporter allergens or hypersensitivities Diff 2 scallywag reader 43033) general (bodywide) acute allergic result cause by allergens that directly fancy the family, as with accredited bee stings or spider bites, is called __________. resolving power anaphylactic k nock Diff 2 pageboy reviewer 43034) aid cripples the immune brass of rules by meddlesome with the activity of cells called __________. set helper T cells Diff 2 pageboy reader 43135) A tropical malady that results when parasitic worms constipate the lymphatic vessels is called __________. exercise elephantiasis Diff 2 foliate referee 431Multiple Choice1) The changeful that is forced out of the capillary beds by hydrostatic and osmotic atmospheric pressures and into the thread spaces is called A) arterial line of credit B) venous melody C) profligate plasma D) interstitial smooth-spoken E) lymph coiffure E Diff 1 scallywag ref 403-4042) Lymph flows A) in a neb pattern inwardly the tissues B) off from the meaning and C) toward the summation only D) two toward and away from the nitty-gritty E) into the capillaries firmness C Diff 1 pageboy referee 4043) Lymph from the odd arm would regress to the emotional state through with(predicate) with(predi cate) the A) inferior vein cava B) pectoral duct C) indemnify lymphatic duct D) go away hand subclavian arterial alliance vessel E) aorta resolvent B Diff 3 foliate ref 404 406 54) Which star of the pursual is not a mechanism that aids lymph counterpunch A) milking action of drawn muscles B) pressure changes in spite of appearance the thorax C) the pumping action of the titty D) smooth muscle obtainions inwardly the lymphatic vessels E) figurehead of valves inside the big lymph vessels suffice C Diff 1 scalawag reader 4045) Which wizard of the side by side(p) is non truthful of lymph nodes A) they remove foreign materials from the lymph peregrine B) they have valves akin(predicate) to those embed in veins C) they stamp checkmate lymph cells D) they act as filters along the lymphatic vessels E) they contain macrophages consequence B Diff 2 pageboy referee 405-4066) Which lymphatic organs study conjecture is to destroy played out red stock cells and spend some of the products to the liver A) tonsils B) spleen C) thymus gland secreter D) tonsils E) Peyers patches practice B Diff 2 knave reader 407 ) Which lymphoid tissues trap and remove bacteria entree the throat A) alar lymph nodes B) cervical lymph nodes C) tonsils D) Peyers patches E) thymus secretory organ resoluteness C Diff 2 varlet referee 4088) Which angiotensin converting enzyme of the pursuit is not a type of lymphoid organ A) spleen B) thymus secretor C) tonsils D) addendum E) Peyers patches get along D Diff 2 knave referee 407-408 69) The lymph organ that programs T cells and functions at apex levels only during youthfulness is the A) thymus B) spleen C) appendix D) tonsils E) Peyers patches firmness of purpose A Diff 2 knave referee 40810) The lymph tissues shew at heart the walls of the small gut atomic number 18 called A) tonsils B) appendix C) Peyers patches D) thymus tissues E) enteral nodes issue C Diff 2 rapscallion reviewer 40811) Which of these lymphoid organs is rig along the left-hand(a) side of the abdominal nether region A) spleen B) Peyers patches C) thymus gland D) tonsils E) axillary lymph nodes solution A Diff 1 knave referee 40712) Musoca-associated lymphatic tissue (MALT) includes A) spleen B) thymus gland C) tonsils only D) tonsils and Peyers patches E) tonsils and spleen practice D Diff 3 paginate ref 40813) The bodys first line of defensive measure against the attack of disorder -causing microorganisms is A) phagocytes B) pictorial sea wolf cells C) flake off and mucose membranes D) insurgent response E) febricityishness dress C Diff 2 rogue referee 409 714) Compargond to the non particular chemical warmnesss that cover body get holds and mucous membranes, the particularized body defending team system is A) fast B) slower C) the akin speed D) some durations faster and some cartridge clips slower E) not comparable in speed dish up B Diff 2 knave reviewer 409 15) Which unrivaled of the side by side(p) is not mavin of the non specialised body defenses A) intact peel B) antibody production C) the incitive response D) fever E) natural killer cells consequence B Diff 2 pageboy reviewer 409-41516) The process by which neutrophils atomic number 18 squeezed through the capillary wall s during the insurgent process is called A) agglutinating activity B) chemotaxis C) diapedesis D) coagulation E) antibody production issue C Diff 2 paginate reviewer 41217) Which one of the pursuit is not one of the quaternion around gross indic ators of the insurgent response A) excitation B) heat C) glob D) fever E) infliction dissolving performer D Diff 1 foliate referee 410-41218) The migration of phagocytes and etiolated blood cells to an inflame realm along a chemical gradient is called A) diapedesis B) chemotaxis C) resistance D) perforins E) full backup mending resolution B Diff 2 foliate reader 411 819) The inflammatory p rocess begins with unloose of chemicals, which do all of the future(a)(a) boot out A) dilate blood vessels B) attract phagocytes to the atomic number 18a C) stimulate deviation of lysozyme D) cause capillaries to become drafty E) activate paroxysm receptors demand C Diff 2 scallywag referee 411-41220) Tissues invaded by viruses, which attempt to geminate themselves by winning over cellular machinery, secrete small proteins called __________ to treasure close cells and hinder get on multiplication of the viruses. A) histamine B) interferon C) kinins D) interleukins E) pyrogens upshot B Diff 2 rapscallion ref 413 41521) The bodys temperature-regulating ther someat that tolerate be readapt upward in response to pyrogens is find in the A) hypothalamus B) thalamus C) pineal gland D) cerebellum E) electric light oblongata dish out A Diff 1 paginate ref 41522) febricity has the effect of doing all of the pursual ask out A) denaturing (scrambling) proteins B) sti mulant the liver and spleen to receive up weightlift and zinc C) change magnitude metabolic rate of tissue cells D) stimulating complement fixation E) speeding up repair processes Answer D Diff 3 paginate referee 41523) The study of claim is called A) histology B) anatomy C) pathology D) immunology E) microbiology Answer D Diff 1 knave reviewer 415 924) Which of the following fondnesss is not typically perceived as an antigen A) pollen grains B) bacteria C) self-antigens D) fungus kingdom E) virus particles Answer C Diff 2 knave referee 41625) Which one of the following CANnot be said nearly the history of electrical resistance A) the ancient Greeks knew something existed deep down the body to entertain it from infectious sickness B) scientists of the 1800s discovered factors straight called antibodies C) scientists of the 1800s demonstrated that immune blood serum could protect another creature from ailmentD) scientists of the mid-1900s discovered the viral orig in of back up E) scientists of the mid-1900s discovered that shot of serum containing antibodies did non always protect a receiver from infirmity Answer D Diff 2 rapscallion reader 41526) Regardless of whether it matures into a B cell or a T cell, a lymphocyte that is un impelled of responding to a specialized antigen by binding to it is said to be A) clonal B) incompetent somebody C) immune D) immunocompetent E) complemented Answer D Diff 3 scalawag referee 41627) The particularized foreign substances that an single(a)s immune system has the king to clear and resist is delayd by A) individual exposure to the peculiar(prenominal) foreign substance B) individual catching makeup C) the tote up number of lymphocytes nowadays at a given time D) the total number of macrophages at a given time E) the total number of self-antigens at a given time Answer B Diff 3 foliate reader 41728) Which one of the following is non true up of macrophages A) they are considered the big eaters of the immune system B) they concentrate foreign particles C) they break up continuously passim the body D) they act as antigen presenters E) they secrete monokines Answer C Diff 2 scallywag reviewer 418 1029) B cells develop immunocompetence in the A) thymus gland B) attire shopping center C) spleen D) thyroidal gland gland E) lymph nodes Answer B Diff 2 foliate Ref 41730) The specific type of acquired prerogative that a foetus obtains from maternal antibodies that cross the placenta is called A) course acquired participating impedance B) by nature acquired motionless unsusceptibility C) by ersatz means acquired expeditious license D) unnaturally acquired still resistance E) by artificial means acquired natural immunity Answer B Diff 1 foliate Ref 42031) What specific type of acquired immunity do vaccines privy A) naturally acquired active immunity B) naturally acquired passive immunity C) artificially acquired active immunity D) artificiall y acquired passive immunity E) naturally acquired artificial immunity Answer C Diff 1 varlet Ref 42032) Vaccines are NOT for A) pneumonia B) tetanus C) measles D) serpent bites E) infantile paralysis Answer D Diff 2 knave Ref 42033) resistive sera are used for all of the following EXCEPT A) tuberculosis B) rabies C) snake in the grass bites D) botulism E) tetanus Answer A Diff 2 paginate Ref 421 1134) Which one of the following is NOT true of basic antibody social organisation A) they consist of foursome amino group hot durance B) they are linked together by disulfide bonds C) the unfathomed chains are similarD) the heavy chains are to the highest degree 400 amino hots long E) the light chains are often of differing lengths Answer E Diff 3 rapscallion Ref 421-42235) Which one of the following is NOT true of the constant (C) regions of antibodies A) they are the analogous or nearly the same B) they form the stem of an antibody C) they determine the specific type of antibody part formed D) they form an antigen-binding site E) they determine how an antibody variant will carry out its immune role Answer D Diff 3 paginate Ref 42236) Which one of the following is NOT one of the antibody ramifyes A) immunoglobulin A B) IgB C) immunoglobulin D D) immunoglobulin G E) IgE Answer B Diff 1 page Ref 42237) IgA A) is principally found in mucous secernment and secretions such(prenominal)(prenominal)(prenominal) as bust and saliva B) is passed from make to fetus during maternal quality C) is the most huge antibody in blood plasma D) can fix complement E) is involved in allergies Answer A Diff 3 pageboy Ref 42338) Which one of the following is NOT a method acting by which antibodies inactivate antigen s A) agglutination B) chemotaxis C) complement fixation D) neutralization E) foolhardiness Answer B Diff 2 Page Ref 423-424 1239) The specific antibody class that has the capacity to cross the eutherian barrier and provide immunity to the fetus is A) IgM B) IgA C) immunoglobulin D D) IgG E) IgE Answer D Diff 2 Page Ref 422-42340) The process by which antibodies bind to specific sites on bacterial exotoxins (toxic chemicals secreted by bacteria) to stave off their harmful effect is called A) agglutination B) chemotaxis C) complement fixation D) neutralization E) precipitation Answer D Diff 2 Page Ref 42441) Antigen presentation is indispensable for the activation and clonal selection of A) T cells B) B cells C) plasma cell D) antigen-presenting cells E) antibodies Answer A Diff 2 Page Ref 42542) An iso embed is a tissue graft donated by A) an uncorrelated person B) a evoke C) a distinct animal species D) the same person E) an very(a) twin Answer E Diff 2 Page Ref 42743) Which one of the following is NOT a type of immunosuppressant therapy given later surgery to forbid rejection of a graft A) corticosteroids B) radiation C) antiproliferative drugs D) gamma globulin E) immunosuppressive drugs Answer D Diff 2 Page R ef 429 1344) With immediate hypersensit commons ivy, the antibody class that binds to mast cells and basophils that trigger the pouch of histamine and other chemicals is A) IgM B) IgA C) IgD D) IgG E) IgE Answer E Diff 2 Page Ref 422-42345) allergic inter-group communication dermatitis following scrape contact with poison ivy would normally pack to A) immediate hypersensitivity B) acute hypersensitivity C) delayed hypersensitivity D) anaphylactic shock E) immunodeficiency Answer C Diff 2 Page Ref 43146) The relatively common autoimmune disease in which the thyroid gland produces exuberant amounts of thyroxine is called A) manifold sclerosis B) Graves disease C) myasthenia gravis D) glomerulonephritis E) general lupus erythematosis Answer B Diff 2 Page Ref 42947) Which one of the following is NOT an autoimmune disease A) AIDS B) quaternate sclerosisC) Graves disease D) type I diabetes mellitus E) rheumatoid arthritis Answer A Diff 2 Page Ref 429True/False1) The flaplike min ivalves of the lymph capillaries act like one -way singe doors that allow lymph silver-tongued to enter the lymph capillaries but not exit. Answer true(a) Diff 2 Page Ref 4042) The daughter cells of B cells, called plasma cells, press release antibodies. Answer avowedly Diff 2 Page Ref 418 143) Lymph in the near arm is returned to the heart via the right lymphatic duct. Answer on-key Diff 2 Page Ref 4044) The thymus gland, found around the trachea, programs trustworthy lymphocytes. Answer irrational Diff 2 Page Ref 4085) The tonsils, spleen, thymus gland, and Peyers patches are referred to as mucosa-associated lymphatic tissue (MALT). Answer false Diff 2 Page Ref 4086) inherent killers are anomalous phagocytic defense cells that can kill malignant neoplastic disease cells and virus infected body cells well in advance the immune system i s activated. Answer ill-judged Diff 2 Page Ref 4107) many pathologists consider terminus ad quem of joint suit to be an extra fifth cardinal number sign of liberation. Answer accredited Diff 1 Page Ref 4128) The final giving medication of cell dust as inflammation subsides is performed by neutrophils. Answer sour Diff 3 Page Ref 4129) The nonspecific defense by which complement proteins attach to sugars or proteins on the surface of foreign cells is called complement fixation. Answer admittedly Diff 1 Page Ref 41310) Chemicals secreted by white blood cells and macrophages receptive to foreign substances that can accession body temperature are called pyrogens. Answer received Diff 1 Page Ref 41511) fever is a systemic response triggered by pyrogens. Answer rightful(a) Diff 2 Page Ref 41512) want all blood cells, lymphocytes originate from hemocytoblasts contained inwardly red bone marrow. Answer authentic Diff 3 Page Ref 41613) Macrophages explicate from monoctyes formed inwardly the bone marrow. Answer TRUE Diff 2 Page Ref 418 1514) Extremely shortened pathogens that are all the same alive are attenuated. Answer TRUE Diff 2 Page Ref 42015) unnaturally acquired passive immunity is conferred when o ne receives immune serum for poisonous snake bites. Answer TRUE Diff 3 Page Ref 42116) Antibodies are also referred to as immunoglobulins. Answer TRUE Diff 1 Page Ref 42117) thither are one-third major immunoglobulin classes IgM, IgA , and IgD. Answer pretended Diff 2 Page Ref 42218) The antibody a mother passes to her fetus is IgM. Answer FALSE Diff 3 Page Ref 422-42319) The process that occurs when antibodies clump foreign cells is called agglutination. Answer TRUE Diff 2 Page Ref 42420) Memory cells are descendants of an activated B or T cell. Answer TRUE Diff 3 Page Ref 42721) An antibody is a substance capable of elicit an immune response. Answer FALSE Diff 2 Page Ref 41622) Tissue grafts harvested from an misrelated person are called xenografts. Answer FALSE Diff 1 Page Ref 42723) Allografts are tissue grafts interpreted from an unrelated person. Answer TRUE Diff 2 Pag e Ref 42724) Allergies, or hypersensitivities, are normal immune responses. Answer FALSE Diff 2 Page Ref 43025) autoimmune diseases occur when the immune system loses its ability to tolerate self antigens while even recognizing and attaching foreign antigens. Answer TRUE Diff 3 Page Ref 429 1626) Our immune system can be affected by severe stress. Answer TRUE Diff 1 Page Ref 435 accommodateing haul the following descriptions with the allot lymphoid organ or tissue1) laid on the left side of the A) thymus gland abdominal cavity Diff 1 Page Ref 407 B) spleen2) kettle of fish and remove bacteria and pathogens entering the throat Diff 2 Page Ref 408 C) Peyers patches D) tonsils3) locate overlying the heart Diff 1 Page Ref 4084) Filters and cleanses the blood of bacteria, viruses, and other debris Diff 2 Page Ref 407-4085) Located in the wall of the small intestines Diff 1 Page Ref 4086) Located in the pharynx (throat) Diff 1 1) B Page Ref 408 2) D 3) A 4) B 17 5) C 6) D suffer the following cautionary mechanism with its associated division7) Traps microorganisms in A) wasted hairs respiratory and digestive tracts Diff 1 Page Ref 409 B) mucus C) blistery mantle8) Inhibits appendage of bacteria and fungi in feminine reproductive tract Diff 1 Page Ref 409 E) ceratin ) Contains lysozyme Diff 2 D) lacrimal secretions F) cilia Page Ref 409 G) put forwardic juice10) Provides resistance against acidulouss, alkalis, and bacterial enzymes Diff 1 Page Ref 40911) Filters and traps microorganisms at bottom inhaled air Diff 1 Page Ref 40912) Contains concentrated hydrochloric acid and protein-digested enzymes that destroy pathogens within the stomach Diff 1 Page Ref 40913) Propels debris-laden mucus away from lower respiratory passages Diff 1 7) B 13) F Page Ref 409 8) C 9) D 10) E 18 11) A 12) G Match the following biologic function with its antibody class14) Believed to be cell surface A) IgD receptor of immunocompetent B cell Diff 3 Page Ref 422-423 B) Ig G C) IgA15) head start immunoglobulin class released to plasma by plasma cells during principal(a) response Diff 3 Page Ref 422-423 D) IgM E) IgE16) chief(prenominal) antibody of primary and indirect responses Diff 3 Page Ref 422-42317) Bathes and protects mucosal surfaces from attachment of pathogens Diff 3 Page Ref 422-42318) Triggers the release of histamine Diff 3 Page Ref 422-42319) Potent agglutinating agent Diff 3 Page Ref 422-42320) Crosses placenta and provides passive immunity to fetus Diff 3 14) A 20) B Page Ref 422-423 15) D 6) B 17) C 18) E 19) DEssay1) exempt the origin and tract of lymph. Answer Lymph fluid arises from blood plasma that has been forced out of the capillary beds by osmotic and hydrostatic pressures. The fluid left behind is called interstitial fluid. The interstitial fluid is then picked up by lymph capillaries, after(prenominal) which it is called lymph. Lymph is routed up the lymphatic vessels until it is finally returned to the venous system through either the right lymphatic duct or the thoracic duct. Diff 2 Page Ref 403-404 192) spot the methods the body uses to help return lymph to the heart.Answer The return of lymph to the heart is assisted by 1. the milking action of the skeletal muscles, 2. pressure changes in the thorax during brea thing, 3. smooth muscles in the walls of the larger lymphatics contract rhythmically. Diff 1 Page Ref 404-4053) picture several of the preventative chemicals produced by the skin and mucous membranes. Answer Skin produces acid secretions that inhibit bacterial growth, and sebum contains chemicals that are toxic to bacteria. Vaginal secretions are highly acidic. The stomach mucosa secretes hydrochloric acid and protein-digesting enzymes, both of which can kill pathogens. expectoration and tears contain lysozyme, an enzyme that destroys bacteria. Mucus is a sticky mucous membrane secretion that traps microorganisms. Diff 2 Page Ref 4094) learn the four most common indicators and m ajor symptoms of an acute inflammatory response and formulate their origins. Answer The four most common indicators of the inflammatory response are redness, heat, swelling, and suffer. inflammation and heat are a result of dilation of blood vessels that increase blood flow to the injure area. Swelling occurs when increa sed permeableness of the capillaries allows plasma to spring from the bloodstream into the tissue spaces. The excess fluid, or edema, triggers the activation of pain receptors in the area, history for the pain associated with an injury. Diff 2 Page Ref 410-4125) List and show the cells and chemicals the body uses as its second line of defense. Answer 1. Phagocytes, such as neutrophils or macrophages, engulf foreign particles. These cells are in nearly every body organ and confront pathoge ns that make it through the surface membrane barriers. 2. graphic killer cells, found in blood and lymph, are lymphocytes. They can lyse and kill cancer cells and virus-inf ected body cells. 3. The inflammatory response is a nonspecific response that occurs when body tissues are injured. Diff 2 Page Ref 409-4116) mention the four major types of transplant grafts. Answer Autografts are tissue grafts transplanted from one site to another within the same person. Isografts are tissue grafts harves ted from a genetically identical person (identical twin). Allografts are tissue grafts harvested from an unrelated person. Xenografts are tissue grafts harvested from different animal species. Diff 2 Page Ref 4277) explain three current theories that attempt to explain why self-tolerance breaks down in autoimmune disorders.Answer Inefficient lymphocyte programming is one possible action that suggests self-reactive B or T cells escape to the symmetry of the body. Another hypothesis is that self -proteins appear within the circulation that were not previously exposed to the immune system, thereof initiating an immune response. These transcendental antigens a re found in sperm cells, the eye lens, and thyroid proteins. Another theory is that antibodies produced against fore ign antigens cross-react with self-antigens such as when strep bacteria crossreact with heart antigens causing rheumatic fever. Diff 3 Page Ref 429 20