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biology > 4.1.1: communicable diseases > Flashcards

4.1.1: communicable diseases Flashcards

1
Q

what are communicable diseases?

A

caused by pathogens that cause harm to the body and lead a person to feel ill

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2
Q

what are the 4 pathogens?

A
  • bacteria (prokaryotes)
  • virus
  • fungi (eukaryotes)
  • protist (eukaryotes)
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3
Q

how do viruses damage host tissues directly?

A
  • take over the cell metabolism
  • viral genetic material gets into the host dna
  • uses host cell to reproduce until the original cell bursts and spreads the viruses to infect other cells
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4
Q

how do protists damage host tissues?

A
  • take over cells and break them open as the new generation emerge
  • digest and use the cell contents as they reproduce
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5
Q

how do fungi damage the host tissues?

A
  • digest living cells and destroy them
  • this gives the symptoms of disease
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6
Q

how do bacteria cause disease in the body?

A
  • produce toxins that poison/damage cells
  • break down cell membranes
  • damage/inactivate enzymes
  • interfere with the with the host cell genetic material
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7
Q

what does ring rot do to potatoes, tomatoes and aubergines?

A

caused by bacteria
- damages leaves, tubers and fruit
- destroys up to 80% of the crop
- no cure
- the field cannot be used to grow potatoes again for at least 2 years

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8
Q

what does tuberculosis do to humans, cows, pigs, badgers and deer?

A

caused by bacteria
- damages and destroys lung tissue
- suppresses the immune system
- people affected by aids/hiv are more likely to get tuberculosis

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9
Q

what does hiv/aids do to humans?

A

caused by viruses
- destroys the immune system by targeting the t helper cells
- person is more susceptible to other infections

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10
Q

what does influenza do to mammals?

A

caused by viruses
- kills the epithelial cells in the gas exchange system
- many deaths are from severe secondary bacterial infections

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11
Q

what does tobacco mosaic virus do to tobacco plants, tomatoes, peppers, cucumbers, petunias and delphiniums?

A

caused by viruses
- damages leaves, stunting growth due to lack of photosynthesis
- can lead to total crop loss

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12
Q

what does malaria do to humans?

A

caused by protists
- make people weak and vulnerable to other infections

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13
Q

how can you prevent malaria?

A
  • killing mosquitoes (vectors that carry the disease)
  • mosquito nets
  • door screens
  • long sleeves
  • vaccinate against malaria
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14
Q

what does tomato blight do to tomatoes?

A

caused by protists
- hyphae penetrate host cells
- destroys leaves, tubers, and fruit

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15
Q

what does black sigatoka do to bananas?

A

caused by fungi
- damages leaves by turning them black = less photosynthesis
- 50% reduction in crops

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16
Q

what does athletes foot do to humans?

A

caused by fungi
- forms a human ring worm
- grows and digests the warm, moist skin between toes
- cracking and scaling = itchy

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17
Q

what is direct transmission in humans?

A

pathogen is transferred directly from one individual to another
- kissing/contact with body fluids
- direct skin to skin contact
- microorganisms from faeces on hands

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18
Q

what is indirect transmission in humans?

A

pathogens travel from one individual to another indirectly
- from inanimate objects
- droplet infection
- vectors

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19
Q

what are the factors that affect the transmission of communicable diseases in animals?

A
  • overcrowded living and living conditions
  • poor nutrition
  • compromised immune system
  • poor disposal of waste
  • climate change
  • culture and infrastructure
  • socioeconomic factors
20
Q

what is direct transmission in plants?

A

direct contact of a healthy plant with any part of a diseased plant

21
Q

what is considered indirect transmission in plants?

A
  • soil contamination (infected plants may leave pathogens)
  • vectors
22
Q

what are factors that affect the transmission of communicable diseases in plants?

A
  • planting varieties of crops that are susceptible to disease
  • over-crowding increases the likelihood of contact
  • poor mineral nutrition reduces resistance of plants
  • damp, warm conditions increase the survival and spread of pathogens and spores
  • climate change
23
Q

what is the physical defenses of plants against pathogens?

A
  • produce high levels of a polysaccharide called callose
  • deposited between sell walls and membranes in cells next to infected cells
  • act as barriers, preventing pathogens entering
  • lignin is added, making mechanical barrier even thicker and stronger
  • callose blocks sieve plates, sealing off the infected area
  • callose is deposited in plasmadesmata between infected cells and their neighbours, sealing them off
24
Q

what are the chemical defenses of plants against pathogens?

A

produce chemicals to either repel insect vectors of disease or kill invading pathogens
- insect repellents (pine resin)
- insecticides (pyrethrins)
- antibacterial compounds (gossypol)
- antifungal compounds (phenols)
- anti-oomycetes (glucanases)
- general toxins (cyanide)

25
Q

what are non-specific defenses against pathogens?

A
  • 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
26
Q

what is phagosytosis?

A

specialised white blood cells that engulf and destroy pathogens

27
Q

what are the stages of phagosytosis?

A

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

28
Q

what are cytokines?

A

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

29
Q

what are antibodies?

A
  • 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
30
Q

how do antibodies defend the body?

A

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

31
Q

what are t-helper cells?

A
  • 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
32
Q

what are t-killer cells?

A
  • destroy pathogen carrying antigen
  • produce chemical called perforin (kills pathogens by making holes in cell membrane)
33
Q

what are t-memory cells?

A
  • part of immunological memory
  • if they meet an antigen a second time
  • divide rapidly = clones
  • destroy the pathogen
34
Q

what are t-regulatory cells?

A
  • 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
35
Q

what are plasma cells?

A
  • produce antibodies to that particular antigen
  • release them
  • live for a few days but releases 2000 antibodies per second while alive
36
Q

what are b-effector cells?

A

divide to form plasma cell clones

37
Q

what are b-memory cells?

A
  • provide immunological memory
  • enable body to make a rapid response when pathogen carrying antigen is encountered again
38
Q

what happens during cell-mediated immunity?

A

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

39
Q

what happens during humoral immunity?

A

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]

40
Q

what are autoimmune diseases and give an example?

A

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)

41
Q

what is the difference between natural and artificial immunity?

A
  • 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
42
Q

what is the difference between active and passive immunity?

A
  • active: body has itself acted to produce antibodies and/or memory cells
  • passive: not made by the body itself
43
Q

how are vaccines made and how do they work?

A

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

44
Q

how do vaccines prevent epidemics?

A
  • 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
45
Q

how does antibiotic resistance occur?

A

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

biology (18 decks)

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