immunology option Flashcards
(136 cards)
1
Q
how does a pathogen try and get into the body?
A
tries to enter through body through hole e.g. eyes, cuts
pathogen enters body tissue and tries to reach blood supply via a capillary
(responses include inflammation and phagocytosis)
pathogen enters blood supply and can migrate around body target cells to reproduce
(response includes B, T and memory cells)
2
Q
what is the first line of defence?
A
natural barriers
e.g. eyes, skin, ears
3
Q
how do eyes protect against pathogens?
A
produce tears containing antibodies and lysozymes
4
Q
how do ears protect against pathogens?
A
produce wax which traps pathogens and contains lysozymes
5
Q
what does ciliated mucous membranes do in the gut, genitals, anus, ears, nose and respiratory pathways?
A
sticky mucus lines passage to trap pathogens
6
Q
how does the respiratory tract protect against pathogens?
A
ciliated cells which waft mucus to the top of the trachea, mucus is swallowed and passes into stomach acid
7
Q
what does the epithelial layer of cells do to protect against pathogens?
A
contains mucus producing goblet cells
8
Q
how does the skin protect against pathogens?
A
outer layer of epidermis
consists of dead keratinised cells
act as a physical barrier
9
Q
what does skin flora do?
A
commensal bacteria which competes with pathogenic bacteria
10
Q
how does the mouth protect against pathogens?
A
lysozyme in saliva
11
Q
how does the urethra protect against pathogens?
A
flow of urine
12
Q
how does the vagina protect against pathogens?
A
acidic
mucus
13
Q
how does blood clotting protect against pathogens?
A
seals wound to prevent pathogen from entering
14
Q
what is lysozyme?
A
in tears and saliva
enzyme attacks peptidoglycan in cell walls of gram-positive bacteria
15
Q
what is the second line of defence?
A
inflammation
phagocytosis
16
Q
what does inflammation cause?
A
redness
swelling
heat
pain
17
Q
what is the function of inflammation?
A
increase blood flow to the area
destroy cause of infection replace and repair damaged tissue
limits effects on body by confining infection to small area
18
Q
what does phagocytosis do?
A
localises any break in barrier and destroys invading microorganisms
19
Q
what are phagocytes?
A
non specific white blood cells
(neutrophils and macrophages)
20
Q
what do neutrophils and macrophages do?
A
engulf and digest foreign particle
21
Q
what happens during phagocytosis?
A
chemotaxis and adherence of microbe to phagocyte
ingestion of microbe by phagocyte (engulf)
formation of phagosome with lysosome to form phagolysosome
digestion of ingested microbe by enzymes formation of residual body and discharge of waste materials
22
Q
what do neutrophils do?
A
engulf and destroy pathogens
numbers rise as a result of infection
short lived
23
Q
what do macrophages do?
A
engulf pathogen and then present antigen on surface
long lived
settle in lymph nodes, spleen and kidney
24
Q
what is the third line of defence?
A
response to an antigen involving lymphocytes due to antigens being recognised as foreign
25
what is the humoral response?
B lymphocytes
26
what is the cell mediated response?
T lymphocytes
27
what are antigens?
proteins/polysaccharides/glycoproteins
specific shape
on surface of bacteria/virus/foreign tissue
can be free molecules e.g. toxins
28
what are antibodies?
large protein molecules that can recognise and neutralise antigens
specific shape complementary to that antigen
quaternary structure proteins (2 heavy, 2 light chains)
29
what are the 3 ways antibodies are able to combat pathogens?
neutralisation
aggulation
opsonisation
30
what happens during neutralisation?
antigens which are toxic are rendered harmless if blocked by being bound to an antibody
31
what happens during aggulation?
forming antibody-antigen complexes so pathogens are held together in large clumps
pathogens cannot move and invade cells
macrophages and neutrophils can move more easily to engulf pathogen
32
what happens during opsonisation?
antibodies coat antigens to help the immune system recognise them
phagocytes have receptors which enable them to bind to and engulf microbes coated with antigen
33
what are the properties of lymphocytes?
produced by stem cells in bone marrow
have specialised receptors on plasma membranes
34
what do B lymphocytes do?
originate in bone marrow
mature in spleen and lymph nodes
develop into plasma B cells (and memory)
plasma B cells secrete antibodies
memory B cells remain in body for years and act as an immunological memory
35
what do T lymphocytes do?
originate in bone marrow
migrate to thymus gland to mature
develop into T helper, killer, memory and suppressor cells
36
what do T helper cells do?
release cytokines which stimulate B lymphocyte cells to develop and stimulate phagocytosis
37
what do plasma B cells do?
secrete antibodies
37
what do T killer cells do?
attack and kill infected cells
38
what do T suppressor cells do?
turn off immune response when infection is cleared
39
what happens to cells with self-antigens?
deleted soon after formation otherwise our own body cell would be destroyed
40
why do you feel ill for a period of time before getting better?
body produces millions of B and T lymphocytes which are all specific to different antigens
time is taken to find the right cell and then for that cell to increase in number
41
what is the function of clonal selection?
to activate B and T lymphocytes
42
what happens during clonal selection?
pathogen enters body and produces toxin
phagocytosis and antigen presentation by macrophages
macrophages must find specific B and T cell that is complementary to bind to antigen
antigen binds to complementary receptor of B or T cell so cell is activated
selected cell then divides rapidly by mitosis (clonal expansion)
43
what is the cell mediated response?
when T cell is clonally selected so differentiates into killer, helper and memory T cells
44
what is the humoral response?
when a B cell is clonally selected so differentiates into plasma and memory B cells
45
why is there a delay (lag phase) on graph?
due to clonal selection and expansion
46
where is there not a delay (lag phase) if infected for a second time?
memory B cells are present
47
what is natural immuntiy?
gained in normal course of living processes
48
what is artificial immunity?
gained by deliberate exposure to antigens/antibodies
49
what is active immunity?
caused by introduction of the antigen
50
what is passive immunity?
introduction of antibody
51
what is an example of passive natural immunity?
antibodies are given via placenta or breast milk
52
what is an example of passive artificial immunity?
antibodies given by injection
53
what is an example of active natural immuntiy?
antibodies made by persons own immune system from infection
54
what is an example of active artificial immunity?
antibodies made by immune system from vaccination
55
what is the definition of vaccination?
deliberate exposure to harmless antigenic material to activate immune response
56
what are examples of antigenic materials?
whole live microorganism
dead microorganism
harmless microorganism
toxoid (harmless form of toxin)
57
what do immunisation programmes do?
give boosters over several years to make sure that enough immunity is required to give long term protection
58
why can vaccinations not be effective sometimes?
some people don't have strong enough immune systems
malnutritions (antibodies are made of proteins)
antigenic variation caused by mutation, antigens no longer recognised by immune system
59
what is antigenic shift?
mixing of antigens between similar strains of virus to produce a new strain
60
what is antigenic drift?
accumulation of mutations over time
genetic mutations leading to new different shaped antigens that produces a new strain
61
what are the features of bacteria?
prokaryote
no membrane bound nucleus
no membrane bound organelles
small ribosomes
cell wall made of peptidoglycan
flagellum
pili
slimy capsule
62
what does peptidoglycan do?
prevents osmotic lysis
maintains pressure inside cell
provides structure and rigidity
63
what shape is bacillus bacteria?
rod-shaped
64
what shape is coccus bacteria?
spherical (balls)
65
what shape is spirillum bacteria?
spiral
66
what colour does gram positive bacteria stain?
purple
67
what colour does gram negative bacteria stain?
pink
68
why does gram positive bacteria stain purple?
thick layer of peptidoglycan
cell wall retains crystal violet dye
69
why is penicillin effective against gram positive bacteria?
weakens cell wall causing cell to burst
70
why does gram negative bacteria stain pink?
thinner peptidoglycan layer and protective outer layer of lipopolysaccharide and lipoprotein outside of cell wall
cell does not retain crystal violet dye
71
why is penicillin not effective against gram negative bacteria?
cell wall is resistant due to lipopolysaccharides
72
what are the properties of E.coli?
rod-shaped
gram negative (stain spink)
in gut
73
what are the properties of B.subtilis?
rod-shaped
gram positive (stains purple)
in soil
74
what are antibiotics?
chemicals produced by fungi and bacteria to interfere with biochemistry of bacteria
can be used without harming human cells
cannot be used against viruses
75
what are the two types of antibiotics?
bacteriostatic
bacteriocidal
76
what does bacteriostatic antibiotics do?
slow down or prevent bacteria from growing
77
what does bactericidal antibiotics do?
kill bacteria
78
what are broad spectrum antibiotics?
effective against a wide range of pathogenic bacteria
usually affect common processes e.g. photosynthesis
79
what are narrow spectrum antibiotics?
only effective against a few types of bacteria and affect more specific processes
80
what types of bacteria do penicillin affect?
kills gram positive
narrow spectrum
bactericidal
readily diffuses through cell wall
81
what does penicillin do?
affects formation of cross linkages in peptidoglycan when new cells are formed
cell wall is weakened so bacterium is likely to burst
then is vulnerable to attack by immune system
82
what does tetrecycline do?
inhibits translation in protein synthesis
inhibits second binding site on 30s ribosomes
prevents binding of tRNA molecules to complementary codon
broad spectrum
bacteriostatic
83
why are antibiotic sensitivity tests carried out?
to find most appropriate antibiotic to use on bacterial infection
84
how does antibiotic resistance occur?
bacteria shows genetic variation due to e.g. mutation
bacteria can pass resistant DNA to non-resistant one during sexual reproduction
when given antibiotic, resistant bacteria survive
surviving bacteria reproduce asexually to form identical clones and pass on resistant gene
population of antibiotic resistant bacteria are produced
85
what causes antibiotic resistance?
if prescribed for trivial infections
if people do not complete prescribed course of antibiotics
used routinely in intensive farming
86
what are the properties of viruses?
very small
can only reproduce in host cells
contain DNA or RNA
surrounded by protein coat (capsid)
87
what are the 3 ways viruses can cause pathogenic effects?
cell lysis
can trigger cells to become cancerous
surpress immune system
88
what does the lytic cycle look like?
loop
attachment and entry
replication
assembly and release
89
what does the lysogenic cycle look like?
integrates into hosts genome
entry and becomes part of DNA
replication
90
why are there 3 subgroups of influenze?
all caused by the same virus but with different antigenic types
91
what is influenza A?
infects humans, birds, pigs
(like influenza B)
92
what is influenza C?
causes mild upper respiratory tract illness
no vaccine
93
what are the antigenic types of influenza based on?
differences between two surface proteins
94
what are the two surface proteins of influenza?
H = haemagglutinin
N = neuraminidase
95
how is influenza transmitted?
person to person by droplet infection
infects cells of upper respiratory tract
96
what are the influenza symptoms?
headache
chills
coughs
fever
apetite loss
tiredness
muscle aches
destructions of respiratory epithelium
97
how can you treat influenza?
anti-viral drugs
98
how can you prevent influenza?
vaccination programmes
99
what is small pox caused by?
DNA-containing virus
Variola major
100
how is small pox transmitted?
by saliva
person to person contact
inhaled
enters small blood vessels in skin, mouth and throat
101
what are the symptoms of small pox?
rash followed by fluid filled blisters (leaves scars)
scars on cornea result in blindness
102
what is the treatments for small pox?
infected people are isolated
given fluids/drugs to control fever
antibiotics for secondary infections
103
why was the small pox vaccination programme a success?
low rate of mutation so little antigenic variation
no animal reservoir for virus
104
what is a carrier?
individual that shows no sign of infection but can spread the disease
105
what is an endemic?
a disease which is always present at low levels in an area
106
what is an epidemic?
a significant increase in the number of cases in an area
often spreading rapidly
107
what is a pandemic?
an epidemic spreading world wide or across a large area
108
what is a vector?
a living organism which transfer a disease from one individual to another
109
what is a toxin?
a chemical produced by a microbe which causes damage to its host
110
what bacteria causes cholera?
vibrio cholerae
111
what are the properties of vibrio cholerae?
gram negative
comma-shaped
motile as flagellum allows it to move through water
112
what does vibrio cholerae do in the body?
lives and multiples in the intestine
produces powerful endotoxin
causes inflammation of mucous membrane of gut
113
how does cholera spread?
contaminated water by faeces containing organism
contaminated food
direct contact between people
114
what are the symptoms of cholera?
diarrhoea due to irritation of bowel by the endotoxin
dehydration and loss of mineral salts
115
what is the treatment for cholera?
rehydration salts
non-contaminated fluids
anti-bacterial drugs
116
how can you prevent cholera?
proper disposal of human faeces (sewage system)
education
117
what cause tuberculosis?
mycobacterium tuberculosis
118
how is tuberculosis transmitted?
airborne droplets from coughs and sneezes
in crowded conditions
119
what are the symptoms of tuberculosis?
attacks lungs and lymph nodes
fever/chills
coughing up blood
weakness/fatigue/loss of appetite
shortness of breath
120
how can you detect tuberculosis?
the heaf test
121
what is the vaccine for tuberculosis?
BCG vaccination
122
what is malaria caused by?
plasmodium
(protoctistan parasite)
123
what is the vector called that malaria is caused by?
female Anopheles mosquito
124
what are the four species of plasmodium?
P.falicparum
P.vivax
P.ovale
P.malariae
125
how is malaria transmitted?
infected mosquito bites human
plasmodia in mosquitos saliva enters bloodstream
invades liver and multiplies and infects blood
another mosquito picks up plasmodium after bite
sexual reproduction in mosquitos intestine produces plasmodia which migrates to salivary glands
mosquitos infects others
126
how does reproduction occur in plasmodium?
plasmodium invades red blood cells and multiplies
plasmodia reproduce asexually in blood
red blood cell ruptures and releases plasmodium
127
what are the symptoms of malaria?
headache
coma
repeated vomiting
generalised convulsions
fever
severe anemia
128
how can you control malaria (reduce bites)?
hang mosquito nets
use insect repellants
129
how can you control malaria (kill vector or reduce vector numbers)?
drain standing water
introduce fish to eat mosquito larvae
spray water surface with diesel oil to stop larvae breathing
spray water with pathogenic bacteria to kill larvae
spray water with insecticide
release sterilised male mosquitos
130
what are the advantages of living vaccines?
behaves same as infectious agent
stimulates powerful response
131
what are the disadvantages of living vaccines?
could mutate to become pathogenic
can cause disease
132
what are the advantages of dead vaccines?
unable to cause disease
easy to store
133
what are the disadvantages of dead vaccines?
may not get as strong a response
134
what are the advantages of RNA/DNA vaccines?
safe as no chance of disease
focuses immune system on particular antigen
135
what are the disadvantages of RNA/DNA vaccines?
only protects against one particular antigen
