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biolala > Immunology > Flashcards

Immunology Flashcards

1
Q

define pathogen

A

an organism that causes a disease, damaging the host

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2
Q

define infectious

A

a disease that may be passed or transmitted from one individual to another

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3
Q

define carrier

A

a person who shows no symptom when infected by a disease organism but can pass the disease to another individual

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4
Q

define disease reservoir

A

where a pathogen is normally found, this may be in humans or another animal and may be a source of infection

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5
Q

define endemic

A

a disease which is always present at low levels in an area

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6
Q

define epidemic

A

where there is a significant increase in the usual number of cases of a disease often associated with rapid disease spread

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7
Q

define pandemic

A

an epidemic occurring worldwide, or over a very wide area, crossing international boundaries and usually affecting a large number of people

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8
Q

define vaccine

A

uses non-pathogenic forms, products or antigens of micro-organisms to stimulate an immune response which confers protection against subsequent infection through memory cells

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9
Q

define antibiotics

A

substances produced by microorganisms which affect the growth of bacteria

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10
Q

define antibiotic resistance

A

where a microorganism which should be affected by an antibiotic is no longer susceptible to it

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11
Q

define vector

A

a living organism which transfers a disease from one individual to another

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12
Q

define toxin

A

a chemical produced by a pathogen which causes damage to cells and tissues of the host

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13
Q

define antigenic types

A

organisms with the same or very similar antigens on the surface. such types are the sub groups or strains of a microbial species which may be used to trace infections. they are usually identified by using antibodies from serum

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14
Q

define antigen

A

a molecule that causes the immune system to produce antibodies against it. these may be individual molecules or those on the surface of cells

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15
Q

define antibody

A

a protein produced by immune cells (B cells) which binds to a specific antigen

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16
Q

define disease

A

the body acting as a host to other living organisms

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17
Q

what does immunology concern?

A

the immune system and how it protects the body

it studies an organisms response to invasion by foreign microbes and their products

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18
Q

give examples of microbes that live on or in the body

A

fungi
protoctista
bacterial species

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19
Q

what do these microbes do to the body in general?

A

cause disease in a parasitic relationship such as secreting toxins

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20
Q

what is the plus side, however, of many of these microbes?

A

they contribute to our health and defend us against disease in a symbiotic or mutualistic relationship, e.g. escherichia coli in the large intestine synthesises vitamin K which is absorbed by the body

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21
Q

how might E.coli benefit from humans?

A

the human body provides E.coli with a safe, comfortable and enclosed living environment in which the bacteria receives the required nutrients like sugars for reproduction and growth

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22
Q

what can bacteria be infected by?

A

a DNA virus called bacteriophages

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23
Q

what 5 diseases do we need to know about?

A

malaria
cholera
tuberculosis
influenza
smallpox

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24
Q

what is the name of the pathogen of cholera?

A

vibrio cholerae

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25
Q

what is the type of pathogen of cholera?

A

gram-negative bacterium

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26
Q

where is the site of infection and the symptoms of cholera?

A

toxins affect the human gut lining, causing a watery diarrhoea, severe dehydration and frequently death

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27
Q

what is the mode of transmission of cholera?

A

humans act as reservoirs or carriers and can contaminate water supplies with the pathogen

the pathogen is transmitted by drinking contaminated water, although it only multiplies in the human host

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28
Q

how to prevent and control cholera?

A

treatment of wastewater, good hygiene and provision of clean drinking water
vaccine may provide temporary protection

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29
Q

what is the treatment of cholera?

A

antibiotic treatment is possible but oral rehydration is the main method of treatment

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30
Q

what is the name of the pathogen of TB?

A

mycobacterium tuberculosis

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31
Q

what is the type of pathogen of TB?

A

either gram-negative or positive bacterium

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32
Q

where is the site of infection and the symptoms of TB?

A

most commonly affect lung and neck lymph nodes

symptoms include coughing, chest pain and coughing up blood

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33
Q

what is the mode of transmission of TB?

A

can be spread rapidly in overcrowded conditions and is transmitted in airborne droplets through coughing and sneezing of infected individuals in close proximity

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34
Q

how to prevent and control TB?

A

BCG vaccination programme for children

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35
Q

how to treat TB?

A

a long course of anitibiotics

36
Q

what is the name of the pathogen of small pox?

A

variola major

37
Q

what is the type of pathogen of small pox?

A

virus

38
Q

where is the site of infection and the symptoms of small pox?

A

small blood vessels of the skin, mouth, throat and lungs causing a rash and blisters

it has a 30% to 60% fatality rate

39
Q

what is the mode of transmission of small pox?

A

airborne droplets of infected individuals in close proximity

it’s eradicated outside labs

40
Q

how to prevent and control small pox?

A

it is now extinct due to immunisation programs and was possible due to low rates of antigenic mutation/variation

in addition, there was no animal reservoir and people were keen to be immunised because of the devastating effects of the disease

41
Q

what is the name of the pathogen of influenza?

A

influenza has three main subgroups, and each has many antigenic types

42
Q

what is the type of pathogen of influenza?

A

virus

43
Q

where is the site of infection and the symptoms of influenza?

A

upper respiratory tract, causing a sore throat, coughing and fever

44
Q

what is the mode of transmission of influenza?

A

airborne droplets through coughing and sneezing of infected individuals in close proximity

45
Q

how to prevent and control influenza?

A

quarantine and hygiene but it isn’t easy to control

annual vaccination programs, but due to new types it is not always effective

46
Q

what is the treatment of influenza?

A

antibiotics are ineffective against influenza and are only used to treat the symptoms of secondary bacterial infection

rest, keep warm, drink plenty of fluids and painkillers

47
Q

what is the name of the pathogen of malaria?

A

plasmodium

48
Q

what is the type of pathogen of malaria?

A

a protoctist

it has two main species with many antigenic types

49
Q

where is the site of infection and the symptoms of malaria?

A

liver cells and red blood cells, causing them to burst when more parasites are produced (lysis)

symptoms include severe bouts of fever and flu-like illness, headache, muscle aches and tiredness. nausea, vomiting and diarrhoea may also occur

50
Q

what is the mode of transmission of malaria?

A

by a vector- a female mosquito from the genus Anopheles when feeding on blood and it becomes endemic in sub-tropical regions

51
Q

how to prevent and control malaria?

A

knowledge of life cycles, nets, clothing and repellant

vaccines are difficult to develop

drug treatment to reduce the chances of infection

52
Q

what is the treatment of malaria?

A

drugs that affect plasmodium outside cells are available but limited success and has side effects

53
Q

what is plasmodium?

A

a single-celled parasite

plasmodium = genus

54
Q

when does the transmission of the parasite by the mosquito occur?

A

when the infected mosquito pierces the skin of a human to take a blood meal

55
Q

why are only adult females vectors of the plasmodium parasite?

A

thy feed on human blood

it is the primary host and does not suffer from the presence of the parasites

56
Q

why are male mosquitos not vectors of the plasmodium parasite?

A

males only feed on the nectar of plants to get sugar

57
Q

describe the five stages of the plasmodium parasite life cycle in the human body

A

1 - the infected mosquito takes a blood meal, and the plasmodium parasite enters the bloodstream

2/3 - plasmodium then travels to and then invades liver cells where the parasite matures

4 - the liver cells rupture and release plasmodium parasites. then they invade red blood cells and multiply asexually. red blood cells also rupture, releasing more plasmodium parasites which invade other red blood cells
the rupture of red blood cells results in severe fever

5 - if a female mosquito feeds on an infected individual, the plasmodium parasites infect the mosquito, which acts as a vector to pass the disease onto another host

58
Q

give five preventative measures for responding to mosquito behaviour

A

sleep under nets

nets are treated with the pyrethroid insecticide

spray indoor walls with insecticide

drain or cover stagnant water e.g. water tanks, ponds

film of oil on water

59
Q

give the reasons for the five preventative measures for responding to mosquito behaviour

A

sleep under nets - mosquitos feed at night

nets treated with insecticide - pyrethroid kills mosquitos

spray indoor walls with insecticide - kills mosquitos as they rest on walls after feeding

drain/cover stagnant water - removes female mosquito’s access to egg-laying sites

film of oil on water - prevents larvae from obtaining oxygen

60
Q

give three preventative measures of biological control against mosquitos and the reasons why

A

introduce fish into water - fish eat the aquatic larvae

infect mosquitos with bacterium - bacteria infection blocks plasmodium development in the mosquito

male mosquitos sterilised with X-rays - no offspring would be produced if they mate with females

61
Q

why have vaccines against malaria been proven difficult to develop?

A

the plasmodium parasite has high mutation rates, and there are many antigenic types

62
Q

what are viruses described as when they are outside of a host cell and what does it mean?

A

being inert
essentially particles and have no metabolic pathways

63
Q

where can they only replicate and what do they do to the host cell?

A

once they are inside a host cell where the enzyme machinery of that host cell is hijacked to make more viral copies

64
Q

what two reproductive cycles can viruses be grouped to?

A

lysogenic and lytic

65
Q

describe the lytic pathway

A

viruses immediately reproduce using the host’s metabolism to copy their nucleic acid and synthesise new protein coat (capsid)

once new viral particles called virions have been assembled in the host cell cytoplasm, they will leave the host cell to infect new cells in two ways

66
Q

what are the two ways viruses will leave the host cell?

A

lysis of the host cells e.g. common cold virus

budding from the host cell surface - when the virus becomes enclosed by part of the host cell membrane e.g. influenza virus

67
Q

describe the lysogenic pathway

A

after the virus penetrates the host cell and sheds the capsid, the viral nucleic acid is integrated into the host cell genome and remains there for many cell generations/divisions with no clinical effect

then, the virus enters the lytic cycle ( due to stressful conditions where the phage DNA is excised from the bacterial chromosome), which is when symptoms are produced, e.g. Herpes simplex virus, HIV virus

68
Q

what 4 ways can viruses be pathogenic and describe them?

A

cell lysis - when viruses escape from cells to infect other cells/organisms (shedding)

production of toxic substances

cell transformation - viral DNA can integrate into the host chromosome. if the DNA inserts into a proto-oncogene/tumour suppressor gene, in can result in the cell undergoing rapid and uncontrolled cell division i.e. becoming cancerous

immune suppression

69
Q

(exam question) how are new HIV particles made?

A

viral DNA transcribes messenger RNA and new viral RNA
messenger RNA carries code for amino acids as triplets of bases/codons to ribosomes
viral protein is assembled
viral protein and viral RNA assembled into new virions/virus particles

70
Q

define antibiotics

A

a substance produced by a fungus which diminishes the population growth of bacteria

71
Q

what are the two modes of action of antibiotics and describe them?

A

1 - bacteriostatic - prevent population growth of bacteria
2 - bactericidal - kill bacteria

72
Q

how can antibiotics treat bacterial infection without harming the patient?

A

they act on bacteria and not on eukaryotic cells/viruses

73
Q

what are broad-spectrum antibiotics?

A

they act against a wide range of disease-causing bacteria by targeting both gram-positive and gram-negative bacterial groups

74
Q

what are narrow-spectrum antibiotics?

A

they are active against a selected group of bacterial types
they can act on either gram-positive or gram-negative bacteria, but not both

75
Q

describe the bacterial cell wall structure

A

contains peptidoglycan consisting of molecules of polysaccharide cross-linked by amino acid side chains, which provides strength and prevents osmotic lysis

in some bacteria, this cell wall is surrounded by an outer layer of lipopolysaccharides

the Gram stain reaction highlights cells with this additional layer (gram-negative), and they retain a counter stain and appear pink/red

the presence of this extra layer provides Gram-negative bacteria with protection from some antibacterial agents such as lysozyme and Penicillin

76
Q

what type of antibiotic is tetracycline?

A

a broad-spectrum, bacteriostatic antibiotic

77
Q

how does tetracycline work?

A

it affects protein synthesis
gram - and gram + bacteria carry out protein synthesis
tetracycline blocks the second tRNA binding site in the large subunit of bacterial ribosomes, preventing the binding of a tRNA molecule’s anticodon to its complementary codon
therefore, amino acids won’t join by peptide bonds, and translation is prevented

78
Q

what type of antibiotic is Penicillin?

A

a narrow-spectrum, bactericidal antibiotic

79
Q

how does Penicillin work?

A

affects the formation of cross-linkages in the peptidoglycan cell wall during growth and division of bacterial cells
it does this by binding to and inhibiting the enzyme transpeptidase which is responsible for the formation of these cross-linkages
penicillin binds irreversibly to transpeptidase, and it is not complementary to the active site of this enzyme, so the enzyme’s function is permanently altered and the cell wall is weakened

80
Q

what type of inhibitor is Penicillin?

A

non-competitive inhibitor as it has a shape that is not complementary to the active site and binding is irreversible

81
Q

what effect will the weakened cell wall have as a result of penicillin on the bacteria?

A

the bacterial cell wall will gain water by osmosis and the cytoplasm will swell
eventually, the cell will lyse as the cell wall is not strong enough anymore

82
Q

is gram-positive more susceptible to penicillin or gram-negative and explain why?

A

Gram-positive bacteria
due to their thick peptidoglycan cell wall

gram-negative bacteria only have a thin peptidoglycan cell wall and contain the outer lipopolysaccharide layer, so penicillin is less effective

83
Q

why are viruses not affected by antibiotics?

A

they have no cell wall, ribosomes, or metabolic pathways to disrupt

84
Q

what are two sources of antibiotic resistance alleles?

A

bacteria divide under optimum conditions and have a high mutation rate. naturally occurring mutations that confer resistance to antibiotics give these bacteria a selective advantage in the presence of antibiotics

plasmids contain the antibiotic resistance allele and it can be transferred from one bacterium to another via conjugation

85
Q

what has overuse of bacteria caused?

A

in the accidental selection of bacterial strains that are completely unaffected by some antibiotics

86
Q

when do bacteria have a selective advantage of having resistance to antibiotics?

A

when the antibiotic is present
so overuse only selects for resistant bacteria, and the frequency of the resistance allele increases

if there are no antibiotics in the environment, then bacteria with this resistance do not provide a selective advantage over bacteria that don’t have resistance

87
Q

give examples of clinically important bacteria that show antibiotic resistance and examples of those that are resistant to several antibiotics

A

bacteria that causes leprosy, TB and gonorrhoea

1- MRSA
2 - clostridium difficile

biolala (21 decks)

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