4.1.1: communicable diseases Flashcards

Question

what are non-specific defenses against pathogens?

Answer 1

- skin - mucous membrane tracts - lysozymes - blood-clotting (platelets release substances that, via a cascade of events, resulting in the formation of fibrin, which itself forms a network, trapping platelets and forming a clot) - fevers (pathogens repoduce

Answer 2

specialised white blood cells that engulf and destroy pathogens

Answer 3

1) pathogens produce chemicals that attract phagocytes 2) phagocytes recognise non-human proteins on the pathogens. this is a response not a specific type of pathogen, but simply a cell or organism that is non-self 3) the phagocyte engulfs the pathogen and encloses it in a vacuole called a phagosome 4) the phagossome combines with a lysosome to form phagolysosome 5) enzymes from the lysosome digest and destroy the pathogen

Answer 4

act as cell-signalling molecules, informing other phagocytes that the body is under attack

Answer 5

- y-shaped glycoproteins - bind to a specific antigen on the pathogen or toxin - made up of 2 identical long polypeptide chains, held together by disulfide bridges

Answer 6

1) antibody of the antigen-antibody complex acts as an opsonin (chemicals that bind to pathogens and 'tag' them so they can be easily recognised) so the complex is easily engulfed and digested by phagocytes 2) most pathogens can no longer effectively invade the host cells once they are part of an antigen-antibody complex 3) antibodies cause pathogens carrying antigen-antibody complexes to clump together = helps prevent them spreading and makes it easier for phagocytes 4) can act as anti-toxins, binding to toxins produced by pathogens and making them harmless

Answer 7

- have cd4 receptors, which bind to the surface antigens on apcs - produce interleukins = type of cytokine - stimulate the activity of b cells which increases antibody production - stimulate production of other typed of t cells attracts - stimulate macrophages to ingest pathogens with antigen-antibody complexes

Answer 8

- destroy pathogen carrying antigen - produce chemical called perforin (kills pathogens by making holes in cell membrane)

Answer 9

- part of immunological memory - if they meet an antigen a second time - divide rapidly = clones - destroy the pathogen

Answer 10

- suppress immune system - stop immune response once pathogen is eliminated - makes sure body recognises self antigens to prevent autoimmune response - interleukins are important for this

Answer 11

- produce antibodies to that particular antigen - release them - live for a few days but releases 2000 antibodies per second while alive

Answer 12

divide to form plasma cell clones

Answer 13

- provide immunological memory - enable body to make a rapid response when pathogen carrying antigen is encountered again

Answer 14

t- lymphocytes respond to cells of an organism that have been changed in some way 1) in non-specific defence system = macrophages engulf pathogens in phagocytosis. they process the antigens from surface of pathogens to form antigen-presenting cells 2) receptors on some of the t-helper cells fit the antigens. they become active and produce interleukins = stimulate t cells to divide rapidly by mitosis = clones of identical activated t-helper cells that all carry the right antigen to bind to a specific protein 3) the t cells may: develop into t-memory cells , produce interleukins that stimulate phagocytosis and b cells , develop into t-kjiller cells

Answer 15

the body responds to antigens found outside cells and to antigen-presenting cells. b- lymphocytes have antibodies on their cell surface membrane. when pathogen enters body, a b-cell with complementary antibodies will bind to antigens on pathogens or to the free antigens. the c cell engulfs and process the antigens to become an antigen presenting hormone 1) activated t-helper cells bind to b cell apc = clonal selection 2) interleukins produced by activated t-helper cells activate b cells 3) activated b cell divides to give clones of plasma cells and be memory cells = clonal expansion 4)clones plasma cells produce antibodies that fit the antigens, bind to antigens and disable them [PRIMARY IMMUNE RESPONSE] 5) some clones b cells develop into b-memory cells, which which divide into plasma cell clones if infected by same pathogen again, which will then produce the right antibody to wipe out pathogen [SECONDARY RESPONSE]

Answer 16

when the immune system stops recognising 'self' cells and starts to attack healthy body tissues e.g. arthritis (affects joints. no cure, but can take anti-inflammatory drugs and steroids)

Answer 17

- natural: when you meet a pathogen for the first time = immune system is activated and antibodies are formed, which can then be used afterwards, if the same pathogens enters the body - artificial immunity: antibodies are formed in one individual (often an animal), extracted than injected into the bloodstream

Answer 18

- active: body has itself acted to produce antibodies and/or memory cells - passive: not made by the body itself

Answer 19

1) pathogen is made safe (i.e. killed or inactivated, weakened strains or toxin molecules have been altered) so that the antigen is intact, but there is no risk of infection 2) small amounts of safe antigen are injected into bloodstream 3) primary immune response is triggered and body produced antibodies and memory cells 4) if you come into contact with the same live pathogen, secondary immune response will be triggered and destroy the pathogen

Answer 20

- mass vaccination can prevent the spread of a pathogen into the wider population - often have to be changed regularly to remain effective - herd immunity = protects those who don's have immunity

Answer 21

if a random mutation produces a bacterium that is not affected by the antibiotic = survive = reproduce = resistant strain