chapter 11 - specific resistance to infection Flashcards
1
Q
what is a macrophage
A
- type of WBC, involved in specific and nonspecific defence
- large phagocytic cells (phagocytosis)
- alert immune system to presence of foreign material
2
Q
what is specific defence
A
- directed towards a particular pathogen
3
Q
what is the immune system / response
A
- system: composed of different types of cells that occur in most organs
- response: cells react to produce immune response, homeostatic mechanism (antibody / cell mediated)
4
Q
what is homeostasis
A
- maintenance of a relatively constant internal environment
- fluctuations in the external environment
5
Q
what is an antigen
A
- substance capable of causing an immune response (specific)
- large molecule, could be a protein, carbohydrate, fat, nucleic acid, whole / part of bacteria
6
Q
what are self and non self antigens
A
- S: substances produced by a persons own body, do not trigger an immune response
- NS: foreign substances that trigger an immune response
7
Q
what is an antibody
A
- 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)
8
Q
what is antibody mediated response
A
- 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
9
Q
what are the different exposures to the same antigen
A
- 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
10
Q
what are the functions of antibodies
A
- 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)
11
Q
what is cell mediated response
A
- 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
12
Q
what is a B cell
A
- type of lymphocyte, produced in bone marrow, incorporated in lymphoid tissue
- capable of responding to a specific antigen
13
Q
what is a T cell
A
- 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
14
Q
process of cell mediated response
A
- 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)
15
Q
what are the types of T cells
A
- 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)
16
Q
what are lymphocytes
A
- 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
17
Q
what is immunity
A
- resistance to infection by invading micro-organisms
18
Q
what is passive immunity
A
- 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
19
Q
what is active immunity
A
- 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
20
Q
what is immunisation
A
- 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
21
Q
what are vaccinations
A
- artificial introduction of antigens or pathogenic substances so that antibodies are produced
22
Q
what are the types of vaccines
A
- 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
23
Q
what is recombinant DNA
A
- 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
24
Q
what are the types of vaccine delivery
A
- 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)
25
what is herd immunity
- 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
26
what age is suggested for first vaccine / what are booster shots
- 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
27
what are the risks of vaccines
- 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
28
what are some ethical concerns of vaccines
- 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
29
what are the factors affecting participation with vaccines
- 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
30
what are antibiotics
- 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)
31
what is antibiotic resistance
- 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
32
what are antivirals
- 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)
33
how will routine vaccinations decrease the risk of disease of a specific pathogen
- 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
