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A-Level Biology > 4.1 Communicable diseases, disease prevention and the immune system > Flashcards

4.1 Communicable diseases, disease prevention and the immune system Flashcards

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1
Q

bacteria facts

A

smaller than eukaryotic cells
reproduce rapidly (20 minutes in optimal conditions)
damage cells through release of toxins
e.g. tuberculosis, meningitis, ring rot (potatoes, tomatoes)

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2
Q

fungi facts

A

often live in skin
hyphae form mycelium
reproductive hyphae grow into skin and releases pores (redness to skin)
live in vascular tissue in plants to gain nutrients
hyphae release extra cellular digestive enzymes to break down cellulose (decays plant)
e.g. black sigatoka (plants), ringworm (cattle), athlete’s foot

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3
Q

protoctista facts

A

enter host cell and feed on contents of cell
malaria parasite Plasmodium has immature forms that feed on haemoglobin
e.g. malaria, potato/tomato later blight

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4
Q

viruses facts

A

invades cell and rakes over genetic machinery and other organelles
causes cells to manufacture more copies of virus
host cell eventually bursts, releasing new viruses to invade new host cells
e.g. HIV, influenza (animals), tobacco mosaic virus (plants)

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5
Q

direct transmission definition

A

passing a pathogen from host to new host with no intermediary

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6
Q

indirect transmission definition

A

passing a pathogen from host to new host, via a vector

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7
Q

transmission definition

A

passing a pathogen from an infected to an uninflected individual

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8
Q

vector definition

A

organism that carries a pathogen from one host to another

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9
Q

means of transmission

A

direct physical contact (touching infected people or contaminated surfaces)
faecal-oral transmission (intaking contaminated food or water)
droplet infection (pathogen carried in tiny water droplets in air)
spores (resistant stage of pathogen carried in air or reside on surfaces or soil)

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10
Q

social factors of transmission

A

overcrowding
poor ventilation
poor health (person who has HIV/AIDS more likely to contract other diseases)
poor diet
homelessness
living with people who migrated from areas where a disease is more common

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11
Q

factors affecting direct physical contact (transmission)

A 
hygiene (wash hands regularly)
keeping surfaces clean
clean and disinfect cuts and abrasions
sterilise surgical instruments
use condoms during intercourse
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12
Q

factors affecting faecal-oral transmission

A

treatment of drinking water
thoroughly wash food (with treated water)
prepare and cook food carefully

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13
Q

factors affecting droplet infection (transmission)

A 
catch it (cover mouth when coughing or sneezing)
bin it - kill it (use and dispose tissue)
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14
Q

factors affecting spore transmission

A

use mask

wash hands after being in contact with soil

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15
Q

indirect transmission of malaria method

A

gametes of plasmodium in person with malaria
female Anopheles mosquito sucks blood
Plasmodium develops and migrates to mosquito’s salivary glands
uninfected person is bitten
Plasmodium migrates to liver then blood
cycle starts again

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16
Q

direct transmission of plant pathogens

A

pathogens in soil enter roots of plant (especially if damaged)
fungi produce spores may be carried by wind
may infect vascular tissue
distributed back to soil when leaves shed
may enter fruit and distributed with seeds (so offspring also afflicted)

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17
Q

indirect transmission of plant pathogens

A

pathogen attaches to insects (vector) when they attack infected plant
they attack uninfected plants and transmit disease

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18
Q

how climate affects disease

A

grow and reproduce quicker in warm, moist conditions
more common with greater variety in warmer climates
pathogens damaged or killed in cold (winter) weather and stunts rate of reproduction

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19
Q

passive defence definition

A

defence present before infection and prevents entry and spread of pathogen in organism

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20
Q

physical defences in plants

A

cellulose cell wall (physical barrier)
lignin thickening of cell walls (waterproof and almost completely indigestible)
waxy cuticle (prevents water that may contain pathogens collecting on cell surface)
bark (physical barrier)
stomatal closure (blocks potential point of entry for pathogen)
callose (large polysaccharide deposited in sieve tube to prevent spread of pathogen around plant)
tylose formation (balloon-like swelling that plugs xylem vessels when full to block spread of pathogens through xylem)

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21
Q

chemical defences in plants

A

plant tissue contain variety of chemicals with with anti-pathogenic properties
some may be present before infection (terpene in tyloses, tannins in bark)
most are in active defence as chemical production requires a lot of energy

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22
Q

active defence definition

A

initiated when pathogen is detected inside the organism

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23
Q

active defences in plants

A

cell walls thicken with more cellulose
deposition
callose deposited between plant cell wall and cell membrane (impedes cellular penetration)
also strengthens cell walls and blocks plasmodesmata
oxidative bursts (highly reactive oxygen molecules, damages cells of invading organisms)
increase production of chemicals
necrosis - deliberate death of infected cells to stop spread

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24
Q

primary defence definition

A

prevents pathogens entering the body / bloodstream

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25
Q

inflammation definition

A

swelling and redness of tissue caused by infection

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26
Q

blood clot formation

A

blood vessel is damaged
platelets bind to exposed collagen to form temporary platelet plug
platelets release clotting factor (activates enzyme cascade)
enzyme cascade causes fibrinogen to form insoluble fibres (attaches to plug)
RBCs trapped (forms clot, dries to form scab)
scab pulls skin together
collagen deposited under skin
stem cells in epidermis divide and differentiate to from new skin cells at edge of cut
new blood vessels form
repair complete when edges of cut drawn together

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27
Q

mucous membrane definition

A

specialised epithelial tissue covered by mucus

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28
Q

expulsive reflexes

A

coughing, sneezing, vomiting
irritation caused by presence of microorganisms or their toxins
causes sudden expulsion of air
carries microorganisms causing irritation

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29
Q

inflammation method

A

mast cells detect microbes and release histamines
causes vasodilation in arterioles (makes capillaries more permeable so WBCs can leave into tissue fluid)
more tissue fluid formed (more plasma leaves)
causes oedema (swelling)
tissue fluid can drain into lymph vessels (pathogens more likely to come into contact with lymphocytes, causing specific immune response)

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30
Q

primary defences in humans examples

A 
skin (physical barrier)
blood clotting and skin repair 
mucous membranes
coughing and sneezing (expulsion reflexes)
inflammation
enzymes in tear fluid (lysozyme)
mucous plug in cervix
maintaining acidic conditions in vagina
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31
Q

secondary defence definition

A

combats pathogens that have already entered body/bloodstream

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32
Q

first line of secondary defence

A

phagocytes (specialised cells in blood and tissue fluid that engulf and digest pathogens)

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33
Q

neutrophil facts

A 
leukocyte / phagocyte 
travel around body in blood
often squeezed into tissue fluid
short-lived
most common phagocyte (40-60%)
die soon after digesting few pathogens
dead neutrophils can collect to form pus
34
Q

neutrophil distinguishable features

A

multi-lobed nucleus
receptors (complementary to antigen)
more lysozymes

35
Q

phagocytosis method

A

receptor on phagocyte’s cell surface membrane binds to antigen on pathogen’s cell cell surface membrane
pathogen engulfed by endocytosis (pseudopodium surround it first)
produces phagosome
lysozymes fuse with phagosome (releasing lysins into it)
digested into amino acids
products absorbed into cytoplasm by diffusion

36
Q

looking at blood smears

A 
RBCs = red, biconcave disc
monocytes = largest WBC, large kidney-shaped nucleus
neutrophil = multilobed nucleus 
lymphocytes = smaller, nucleus almost fills cells
37
Q

macrophage facts

A

travel in blood as monocytes
produced in bone marrow
mature in lymph nodes
when engulfing pathogen, saves its antigen and moves it to special protein complex in surface of cell
becomes antigen-presenting cell
special protein complex makes sure antigen-presenting cell isn’t attacked by other phagocytes

38
Q

antigen presentation (active immunity)

A

antigen-presenting cell moved around body
comes in contact its specific cells (that can activate full immune response - T and B lymphocytes)
only one T and B lymphocytes
antigen-presenting cells increase chances antigen will come in contact with them

39
Q

specific immune response

A

activation of B and T cells = clonal selection
initiates complex series of events that leads to production of antibodies and memory cells (for long-term immunity)
series of events coordinated by cytokines (hormone-like chemicals)
stimulates differentiation and activity of macrophages, clonal expansion (B and T cells)

40
Q

specialised T cells

A

T helper cell: releases cytokines (stimulates clonal expansion of B cells)
T killer cell: kills host-body cells displaying foreign antigen
T memory cell: stays in blood stream for long term immunity
T regulator cell: shuts down immune response after pathogen successfully removed

41
Q

specialised B cell

A

plasma cell: circulate in blood, making and releasing antibodies
B memory cell: remain in body for immunological memory

42
Q

cell signalling definition

A

communication between cells

43
Q

cell signalling in immune response

A

antigens on pathogens state they are foreign to body cells
infected cells with foreign antigen on plasma membrane communicate to lymphocytes for clonal selection and T killer cells they need to be killed
macrophages ingest and incorporate antigens on plasma membrane (antigen-presenting cell), for lymphocytes for clonal selection
T helper cells release cytokines (stimulates B cells for clonal expansion)

44
Q

autoimmune disease definition

A

immune system attacks part of the body

44
Q

examples of autoimmune diseases

A

lupus - swelling and pain (antibodies attack nuclei of cells)
arthritis - painful inflammation (antibodies attack membranes around joint)

45
Q

where B and T lymphocytes made and mature

A

both made in bone marrow
B lymphocytes mature in bone marrow
T lymphocytes mature in thymus

46
Q

clonal selection method

A

foreign antigen detected by T and B lymphocytes with complementary shape receptors
helped by antigen-presenting cells, infected cells with foreign antigen on membrane

47
Q

antibody definition

A

immunoglobulins, complex proteins they bind to specific antigens, released by plasma cells

48
Q

structure of antibody

A 
heavy and light polypeptide chains held together by disulphide bond
hinge region (for flexibility so can attach to multiple antigens)
variable region (specific shape complimentary to specific antigen)
constant region (same in all antibodies, may have site to bind to phagocytic cells)
49
Q

types of antibodies

A

opsonins
agglutinins
antitoxins

50
Q

opsonin role

A

opsonisation
bind to antigens on pathogen
act as binding site for phagocytes (easier phagocytosis)
may bind to specific antigens with specific role (neutralisation)
some may stick to molecule not present in host cell e.g. peptidoglycan

51
Q

agglutinin role

A 
agglutination 
bind to multiple pathogens (cross link)
clumps pathogen together
become too big to enter host cell
more likely to encounter and be engulfed by phagocyte
52
Q

antitoxin role

A

binds to toxic molecules released by pathogen, renders them useless

53
Q

primary vs secondary immune response

A

primary:
time delay to trigger immune response after first infection
no memory cells (slower and less antibody production)

secondary:
antibody production immediate (faster clonal selection and expansion due to memory lymphocytes)
more and faster antibody production

54
Q

why new drugs need to be developed

A

new drugs needed to combat new diseases
new antibiotics needed due to antibacterial resistance
different medications to suit different people (e.g. allergies or lifestyle choices)
maintain biodiversity (new sources of drugs)

55
Q

how drugs are made

A

microbes and some plants produce compounds with medicinal properties

56
Q

personalised medicine

A

possible to screen genome of plants / microorganisms to identify how medicinal compounds produced
eventually able to sequence genes from individuals and develop specific drugs for each person

57
Q

synthetic biology

A

development of new molecules that mimic biological molecules e.g. enzymes

58
Q

antibiotic definition

A

used to treat / avoid bacterial infection

59
Q

benefits of antibiotics

A

prevents infection after surgery (reduces complication / death rates)
treat infections body can’t “fight off”

60
Q

risks of antibiotics

A

overuse / misuse allows bacterial strains to become resistant to antibiotics (reduces effectiveness)

61
Q

types of immunity

A

artificial
natural
passive
active

62
Q

active immunity definition

A

through activities of person’s own immune system

more long term

63
Q

passive immunity definition

A

without activation of lymphocytes (antibodies made by another person)
eventually lost

64
Q

artificial immunity definition

A

gained by deliberate exposure to antigens or antibodies

65
Q

natural immunity definition

A

gained in normal cause of living

66
Q

example of natural active immunity

A

result of infection

67
Q

example of natural passive immunity

A

antibodies provided via placenta or breast milk

68
Q

example of artificial active immunity

A

infection of weakened version of disease / antigenic material

69
Q

example of artificial passive immunity

A

injection of antibodies

70
Q

vaccination definition

A

deliberate exposure to antigenic material, activating immune system to make immune response and provide immunity (due to memory lymphocytes in bloodstream)

71
Q

epidemic definition

A

disease spread quickly, affecting large proportion of population

72
Q

pandemic definition

A

disease spread worldwide over many countries and continents

73
Q

examples of antigenic material

A

harmless / dead version of disease
microbes with very similar-shaped antigens
antigens themselves

74
Q

herd vaccination

A

using vaccine to provide immunity to (almost) all of population at risk
stops infection spreading

75
Q

ring vaccination

A

vaccinate all people living with or near victim
requires people to report victims
contains spread within ring

76
Q

people who need to be immunised

A

elderly/young children (weak immune system / little time to build up immunity to many diseases)
people with HIV/AIDS (weak immune system, can’t produce many antibodies themselves)
pregnant women (foetus underdeveloped immune system)
health workers/people living near outbreak (higher risk of getting disease)
people with chronic diseases / had chemotherapy/transplant (already in poor health, can’t withstand further disease)

77
Q

why people choose to not get immunised

A 
too busy / lazy to go to doctors
media scare stories
concerned about side effects
allergic to vaccine
dear of needles
religious reasons 
cost of vaccine too expensive
78
Q

why government want people to be vaccinated aside health benefits

A

prevention of disease can minimise sick days off work (minimises damage to economy)
costs less to immunise than treat people
health service may not be able to cope if large people became infected

79
Q

why elderly et al. encouraged to get vaccine for influenza every year

A

vaccine changed every year
different strains each year
new strains have different antigens
old antibodies not complementary to new antigen
new vaccine encourage new antibodies to be made

A-Level Biology (24 decks)

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