chapter 11 - specific resistance to infection

Question 1

what is a macrophage

Answer 1

• type of WBC, involved in specific and nonspecific defence
• large phagocytic cells (phagocytosis)
• alert immune system to presence of foreign material

Question 2

what is specific defence

Answer 2

• directed towards a particular pathogen

Question 3

what is the immune system / response

Answer 3

• system: composed of different types of cells that occur in most organs
• response: cells react to produce immune response, homeostatic mechanism (antibody / cell mediated)

Question 4

what is homeostasis

Answer 4

• maintenance of a relatively constant internal environment

- fluctuations in the external environment

Question 5

what is an antigen

Answer 5

• substance capable of causing an immune response (specific)

- large molecule, could be a protein, carbohydrate, fat, nucleic acid, whole / part of bacteria

Question 6

what are self and non self antigens

Answer 6

• S: substances produced by a persons own body, do not trigger an immune response
• NS: foreign substances that trigger an immune response

Question 7

what is an antibody

Answer 7

• specialised protein that is produced in response to a non self antigen
• belong to a group of proteins called immunoglobulin (lg)
• many different types (lgA, lgD, lgE, lgM, lgG)

Question 8

what is antibody mediated response

Answer 8

• produces and releases antibodies into blood / lymph, provides resistance / attack invading agents
  1. B cell remains in lymphoid tissue until activated / sensitised by an antigen.
  2. one type of B cell is sensitised, enlarges and divides
  3. clones of B cell are formed
  4. most B cells become plasma cells and secrete antibodies (circulate body), these combine to form antigen-antibody complex
  5. some B cells become memory cells, spread to bodies tissues, allow response to occur more rapidly if there is a second antigen exposure

Question 9

what are the different exposures to the same antigen

Answer 9

• 1: primary response, takes several days for large amounts of antibodies to accumulate
• 1.5: secrete antibodies = increased antibodies in blood, peak is reached and decline occurs, memory cells remain
• 2: secondary response, much faster, plasma cells form straight from memory cells, antibody levels in blood increase
• 2.5: most of the time the antigen doesn’t cause illness due to such fast detection

Question 10

what are the functions of antibodies

Answer 10

• inactivate: foreign enzyme by inhibiting reaction with other cells / compounds
• bind to surface: of viruses and prevent them from entering cells
• coat bacteria: more easily consumed by macrophages
• agglutination: cause clumping
• dissolve organisms
• make insoluble: by reacting with soluble substances (more easily consumed)

Question 11

what is cell mediated response

Answer 11

• provides resistance to intercellular phase of bacterial / viral infections (those pathogens that specialise in invading / replicating in host cells, e.g HIV)
• provide resistance fungi and parasites, rejection of transplants, fights cancer cells

Question 12

what is a B cell

Answer 12

• type of lymphocyte, produced in bone marrow, incorporated in lymphoid tissue
• capable of responding to a specific antigen

Question 13

what is a T cell

Answer 13

• type of lymphocyte, produced in bone marrow and mature in thymus, incorporated in lymphoid tissue
• capable of responding to a specific antigen
• become activated after B cells encounter antigen and they travel to nearest lymph node to present to T cells

Question 14

process of cell mediated response

Answer 14

• same division process as antibody mediated response
• instead of producing plasma and memory cells, produce killer, helper and suppressor T cells (migrate to area with increased antigens)

Question 15

what are the types of T cells

Answer 15

• killer: attach themselves to invading cell and secrete substance that destroys antigen
• helper: secrete substances that; cause lymphocytes to become sensitised (intensifies IR), attract macrophages (intensify phagocytic activity of macrophages)
• suppressor: act when immune system becomes too excessive / when infection is gone, release substance that inhibits b and T cell activity (slows / stops immune system)

Question 16

what are lymphocytes

Answer 16

• type of WBC (20-30%), involved in specific and non specific defence, produced in bone marrow and lymphoid tissue
• move around blood / enter tissue or lymph
• types: B cells and T cells

Question 17

what is immunity

Answer 17

• resistance to infection by invading micro-organisms

Question 18

what is passive immunity

Answer 18

• acquires antibodies from mother or injection
• natural (maternal): antibodies enter blood stream across placenta / breast milk, short term immunity, no specific immune response, no memory cells
• artificial: antibodies enter blood stream via injection, short term immunity, no specific immunity, memory cells, no symptoms

Question 19

what is active immunity

Answer 19

• acquires antigen via infection or injection
• natural (infection): ability to manufacture antibodies results from pathogen entering body, person has symptoms, specific immune response, long term immunity, memory cells produced
• artificial: antigen given via a vaccine injection, specific immune response, long term immunity, memory cells, no symptoms

Question 20

what is immunisation

Answer 20

• programming the immune system so that the body can respond rapidly to infecting microorganisms, can occur naturally/ artificially
• naturally immunised: against chicken pox, mumps, measles, diphtheria

Question 21

what are vaccinations

Answer 21

• artificial introduction of antigens or pathogenic substances so that antibodies are produced

Question 22

what are the types of vaccines

Answer 22

• living attenuated: live microorganisms of reduced virulence, antibodies, lasts longer
• dead: dead microorganisms, short
• toxoids: inactivated toxins produced by bacteria
• sub unit: fragment of microorganism

Question 23

what is recombinant DNA

Answer 23

• altering the DNA in the microorganism so that it is less virulent
• inserting DNA from pathogen into harmless bacteria to produce antigens, vaccination of harmless bacteria = immunity
• increases immunity, decreases number of deaths

Question 24

what are the types of vaccine delivery

Answer 24

• injection: via syringe (most common)
• oral: sweet syrup / lumps of sugar (polio vaccine), not in aus
• new: fine spray into nostrils (USA), skin patches (self administered), vaccines in food (difficult to control dose)

Question 25

what is herd immunity

Answer 25

• reducing the chance of disease in susceptible individuals, increasing immunity in population
• depends on high proportion of population being immunised (less chance of disease being transmitted)
• problem: incidence of disease declines, people become complacent and decide risk of getting disease is less than that of side effects, outbreak can occur

Question 26

what age is suggested for first vaccine / what are booster shots

Answer 26

• after 2 months (baby has antibodies from mother which will remove antigen in vaccine)
• BS: first does of vaccine doesn’t activate enough b-cells / memory cells, booster shots activate more
• -> timing needs to be correct (antibodies can eliminate vaccine before more B cells are activated), period of 2 months in between is required

Question 27

what are the risks of vaccines

Answer 27

• allergic reaction: not from vaccine but the medium it was cultured in (influenza -> made in fertilised eggs -> allergic to egg protein will react) (hepatitis b -> made with yeast)
• isolation: of just one virus from tissue used to culture medium is impossible (cross species disease introduction)
• preservatives: used to make vaccines -> can affect nervous system or other health problems

Question 28

what are some ethical concerns of vaccines

Answer 28

• manufacture: viruses require a host, concerns about treatment of animals and humans (tissue aborted from human foetuses, influenza is cultured in chicken embryos)
• testing: developed countries often produce them (education standees are low, not informed of risks = exploitation), animals (mice, other mammals, birds, amphibians, fish) (sacrifice animals for science)
• decisions: parents need to weigh up risks / be well informed (for themselves and children)
• -> HPV vaccine: HPV is an STI that causes genital warts and cervical cancer, most effective on girls yet to have sex (11-12), many believe this is too young (promote promiscuous behaviour), others believe it will prevent serious illness later in life and have no effect on sexual behaviour

Question 29

what are the factors affecting participation with vaccines

Answer 29

• economic: in Australia most immunisations are free (government rebate), may not have access, can’t afford them (low average income), assistance of WHO
• social: poor education regarding risks / benefits, education of women / mothers, Internet sites with misinformation, ethical / religious beliefs, day care centres is now mandatory, peer pressure, medical risks (allergies)
• cultural: family history / background of receiving vaccinations, animal / embryo testing, traditional / alternative medicine, recommended not to by practitioners

Question 30

what are antibiotics

Answer 30

• drugs produced from microorganisms / fungi used to fight infections of / inhibit growth of bacteria
• antigen specific, cannot treat viral infections
• bacteriostatic: stop bacteria from producing / disrupts protein synthesis (streptomycin)
• bactericidal: kill bacteria by changing structure of cell wall / membrane or disrupting the action of essential enzymes (penicillin and cephalosporin)

Question 31

what is antibiotic resistance

Answer 31

• high number of bacteria (few resistant to antibiotic) -> antibiotics kills infection causing bacteria / good bacteria that protects body from infection -> resistant bacteria now have preferred conditions to grow, thrive and take over -> bacteria can even transfer drug resistance to other bacteria
• overcoming problem: reviving antibiotics by using them in a combination with other substances, to genetically engineer bacteria to disable antibiotic- resistant gene

Question 32

what are antivirals

Answer 32

• act on virals, killing virus means killing the host cells

- solution: identify viral proteins / design chemicals to disable virus (so it never enters the host)

Question 33

how will routine vaccinations decrease the risk of disease of a specific pathogen

Answer 33

• immunisation of individual via active immunity leads to antibody / memory cells
• on second exposure no symptoms will be produced
• leads to herd immunity as there are fewer potential sufferers and it is more difficult for disease to spread
• reduced number of unaffected carriers
• programmed immune system to produce antibodies against pathogen