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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

(80 cards)

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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
inflammation definition
swelling and redness of tissue caused by infection
26
blood clot formation
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
27
mucous membrane definition
specialised epithelial tissue covered by mucus
28
expulsive reflexes
coughing, sneezing, vomiting irritation caused by presence of microorganisms or their toxins causes sudden expulsion of air carries microorganisms causing irritation
29
inflammation method
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)
30
primary defences in humans examples
``` 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 ```
31
secondary defence definition
combats pathogens that have already entered body/bloodstream
32
first line of secondary defence
phagocytes (specialised cells in blood and tissue fluid that engulf and digest pathogens)
33
neutrophil facts
``` 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
neutrophil distinguishable features
multi-lobed nucleus receptors (complementary to antigen) more lysozymes
35
phagocytosis method
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
looking at blood smears
``` RBCs = red, biconcave disc monocytes = largest WBC, large kidney-shaped nucleus neutrophil = multilobed nucleus lymphocytes = smaller, nucleus almost fills cells ```
37
macrophage facts
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
antigen presentation (active immunity)
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
specific immune response
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
specialised T cells
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
specialised B cell
plasma cell: circulate in blood, making and releasing antibodies B memory cell: remain in body for immunological memory
42
cell signalling definition
communication between cells
43
cell signalling in immune response
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
autoimmune disease definition
immune system attacks part of the body
44
examples of autoimmune diseases
lupus - swelling and pain (antibodies attack nuclei of cells) arthritis - painful inflammation (antibodies attack membranes around joint)
45
where B and T lymphocytes made and mature
both made in bone marrow B lymphocytes mature in bone marrow T lymphocytes mature in thymus
46
clonal selection method
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
antibody definition
immunoglobulins, complex proteins they bind to specific antigens, released by plasma cells
48
structure of antibody
``` 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
types of antibodies
opsonins agglutinins antitoxins
50
opsonin role
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
agglutinin role
``` 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
antitoxin role
binds to toxic molecules released by pathogen, renders them useless
53
primary vs secondary immune response
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
why new drugs need to be developed
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
how drugs are made
microbes and some plants produce compounds with medicinal properties
56
personalised medicine
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
synthetic biology
development of new molecules that mimic biological molecules e.g. enzymes
58
antibiotic definition
used to treat / avoid bacterial infection
59
benefits of antibiotics
prevents infection after surgery (reduces complication / death rates) treat infections body can’t “fight off”
60
risks of antibiotics
overuse / misuse allows bacterial strains to become resistant to antibiotics (reduces effectiveness)
61
types of immunity
artificial natural passive active
62
active immunity definition
through activities of person’s own immune system | more long term
63
passive immunity definition
without activation of lymphocytes (antibodies made by another person) eventually lost
64
artificial immunity definition
gained by deliberate exposure to antigens or antibodies
65
natural immunity definition
gained in normal cause of living
66
example of natural active immunity
result of infection
67
example of natural passive immunity
antibodies provided via placenta or breast milk
68
example of artificial active immunity
infection of weakened version of disease / antigenic material
69
example of artificial passive immunity
injection of antibodies
70
vaccination definition
deliberate exposure to antigenic material, activating immune system to make immune response and provide immunity (due to memory lymphocytes in bloodstream)
71
epidemic definition
disease spread quickly, affecting large proportion of population
72
pandemic definition
disease spread worldwide over many countries and continents
73
examples of antigenic material
harmless / dead version of disease microbes with very similar-shaped antigens antigens themselves
74
herd vaccination
using vaccine to provide immunity to (almost) all of population at risk stops infection spreading
75
ring vaccination
vaccinate all people living with or near victim requires people to report victims contains spread within ring
76
people who need to be immunised
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
why people choose to not get immunised
``` 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
why government want people to be vaccinated aside health benefits
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
why elderly et al. encouraged to get vaccine for influenza every year
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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