the immune system Flashcards
1
Q
what are the two ways organisms can infect you
A
via the external epithelia: skin surface, wound, insect bite
mucosal surface: airway, GI tract, reproductive tract
2
Q
how do we defend ourselves from infection
A
barriers
3
Q
give examples of the body’s infection barriers
A
mucus lining the nose to trap infectious material
cilia lining the lungs to sweep mucus up
defensins in the intestine (host defence peptides)
4
Q
what is the first response to infection
A
inflammation
5
Q
what are the steps of inflammation
A
toll like receptors recognise foreign molecules
they initiate inflammation
histamine, defensins, peptides, cytokines, chemokines are released and recruit other cells for the immune response
the immune response is triggered resulting in heat, redness, swelling and pain
6
Q
what are toll like receptors
A
patter recognition molecules
7
Q
what is a node
A
a point in a network of diagram at which lines or pathway intersect or branch
8
Q
what is lymph
A
a colourless fluid containing white blood cells, which bathes the tissues and drains through the lymphatic system into the blood stream
9
Q
what are the components of the lymphatic system
A
thymus, spleen, lymph nodes
10
Q
what are lymph nodes
A
nodular aggregates located along lymphatic system (a communication centre for immune cells so they can coordinate a response)
11
Q
how does lymph enter the lymph node
A
through the afferent lymph vessels
12
Q
what is the difference between red blood cells and white blood cells
A
red blood cells carry oxygen
white blood cells are immune cells
13
Q
list all the types of white blood cells (9)
A
macrophage neutrophils lymphocytes - b and t cells basophils eosinophils mast cells monocytes dendritic cells natural killer cells
14
Q
what types of white blood cells are members of the innate immune system
A
neutrophil mast cells eosinophils dendritic cells basophils macrophage monocytes natural killer cells
15
Q
what types of white blood cells are members of the adaptive immune system
A
lymphocytes:
b cells
t cells
16
Q
what kind of response does the innate immune system provide
A
the same response over and over again
17
Q
what kind of response does the adaptive immune system provide
A
an adapted immune response specific to the infection at hand
18
Q
what is complement
A
a cascade of proteins in serum (roughly 30 proteins in blood plasma)
19
Q
what activates complement
A
antibodies or molecules from pathogens
20
Q
which immune response does complement amplify
A
inflammation
21
Q
what does complement do
A
either directly kills the pathogen or attracts immune cells
22
Q
how many bacteria can neutrophils capture
A
on or two
23
Q
which type of white blood cell is most abundant
A
neutrophils
24
Q
neutrophils are ………. phagocytic cells
A
active
25
how do neutrophils kill pathogens
they can consume them and also use NETs
26
what are NETs
sticky strands of DNA
27
how are neutrophils recruited
by inflammation in the tissues
28
what do neutrophils turn into when they die
snot
29
where are macrophages found
in all tissues
30
how many bacteria can macrophages capture
hundreds - they are the best phagocytic cells
31
where do macrophages develop
in tissues form precursors
32
how do macrophage kill pathogens
they consume them then kill them
33
what activates macrophages
inflammation in the tissues
34
are macrophages long lived or short lived
long lived
35
where are dendritic cells formed
in tissues from precursors
36
dendritic cells are active ………….. cells
phagocytic
37
what response can dendritic cells activate
the adaptive immune response
38
what do dendritic cells carry to the lymph nodes
proteins
39
where do dendritic cells migrate from
out of peripheral tissues
40
how can dendritic cells activate the adaptive immune response
they communicate with t cells
41
where are dendritic cells found
in all tissues and take bacteria back to the lymph node instead of staying in the tissue
42
what is a pathogen
any disease causing organism
43
does a foreign molecule have to be pathogenic to elicit an immune response
no
44
the first line of defence prevents pathogens form doing what
entering the body
45
a properly functioning immune system distinguishes ……………... from self
no self
46
what do immune cells do
produce receptor like molecules that bind specifically to molecules from foreign cells or viruses and activate defence responses
47
the specific binding of immune receptors to foreign molecules is a type of what
molecular recognition
48
is adaptive immunity found in all animals
no, only in vertebrates
49
is innate immunity found in all animals
yes
50
What does molecular recognition in innate immunity involve
a small set of receptor proteins that bind to molecules that belong to a group of viruses, bacteria or other pathogens. This binding activates internal defences, enabling a response to a broad range of pathogens
51
is the innate response rapid or slow
rapid
52
what are the innate internal defences
phagocytic cells
NKCs
antimicrobial proteins
inflammatory response
53
is the adaptive immunity response rapid or slow
slower
54
What does molecular recognition in adaptive immunity involve
recognition of traits specific to particular pathogens, using a vast array of receptors very very specific
55
what are the two adaptive immunity responses
humoral response
| cell mediated response
56
what is the humoral response
antibodies defend against infection in body fluids (occurs in the blood ad lymph)
57
what is the cell mediated response
Specialized T cells destroy infected host cells
58
what is another name for the adaptive immune response
the acquired immune response
59
what response I developed first adaptive or innate
innate
60
is innate immunity found in plants
yes
61
how is prevention of lung infection prevented by cilia
the pathogens are trapped in the mucous lining and are then swept up the trachea by the cilia to be swallowed down the oesophagus
62
how do saliva, tears and mucous help prevent infection - the physical role
they bathe exposed epithelia and provides a washing action that inhibits colonisation of fungi and bacteria
63
how do saliva, tears and mucous help prevent infection - the chemical role
body secretions create a hostile environment for many pathogens
e.g. lysozyme destroys the cell walls of bacteria
e.g. ingested pathogens encounter the acidic environment of the stomach
oil and sweat gland secretions make the skin acidic preventing colony growth.
64
what do innate immune cells rely on
toll like receptors
65
what is a toll like receptor
a mammalian recognition protein
66
Upon recognition of pathogens, what do TLR do
they release a signal that initiate responses tuned to the invading microbe
67
TLR proteins bind to fragments of molecules characteristic of a set of pathogens. Name some examples of TLR and their functions
TLR3 - bind to RNA on viruses
TLR4 - binds to lipopolysaccharides found on many bacteria
TLR5 - binds to flagellin, a protein of bacterial flagella
68
what are the two main types of mammalian phagocytic cell
macrophages and neutrophils
69
Describe the role of neutrophils
they circulate in the blood
they are attracted by signals from infected tissues
they engulf and destroy the pathogens
70
Describe the role of macrophages
means "big eaters"
they are large phagocytic cells
they can move throughout the body or reside permanently in organs/tissues where they are likely to encounter pathogens
71
which 2 other cells have roles in the innate immune response
dendritic cells
| eosinophils
72
describe the role of dendritic cells
mainly populate tissues that contact the environment e.g. skin
they stimulate adaptive immunity against pathogens that they encounter and engulf
73
describe the role of eosinophils
found in tissues underlying an epithelium
important in defending against multicellular invaders e.g. parasitic worms
eosinophils discharge destructive enzymes
74
natural killer cells are also involved in cellular innate defences, what do they do
they circulate the body and detect abnormal surface proteins characteristic of virus infected or cancerous cells
75
do natural killer cells engulf stricken cells
no
76
how do natural killer cells kill the pathogen
they release chemicals that lead to cell death, inhibiting further spread of the virus or cancer
77
many innate defences involve which organ system
the lymphatic system
78
what are the components of the lymphatic system
Thymus, spleen, lymph, lymph nodes, bone marrow, lymph vessels
79
what do macrophages that reside in the lymph nodes do
engulf pathogens that have entered the lymph from the interstitial fluid
80
how do dendritic cells stimulate adaptive immunity
they reside outside the lymphatic system but migrate to the lymph nodes after interacting with pathogens. within the lymph nodes they interact with other immune cells, stimulating adaptive immunity
81
pathogen recognition triggers the production and release of a variety of ……….. and ………… that attack pathogens or impede their reproduction
peptides
| proteins
82
how do antimicrobial peptides affect pathogens
they disrupt membrane integrity
83
are antimicrobial peptides found in insects
yes
84
are interferons and complement proteins found in insects
no they are unique to vertebrates
85
what are interferons
proteins that provide innate defence by interfering with viral infections
86
where are interferons excreted from
virus infected body cells
87
what do interferons induce
uninfected cells to produce substances that inhibit viral replication
88
interferons limit the cell to cell spread of viruses in the body helping control viral infections such as ………….
the cold and influenza
89
where else can interferons be excreted from and what is their function in this case
white blood cells
| they enhance phagocytic ability of macrophages
90
complement proteins circulate the body in an inactive form. how do they become activated
by substances on the surface of many pathogens
91
what happens when complement is activated
a cascade of reactions that lead to lysis of invading cells
92
name 2 changes that reflect a local inflammatory response
swelling and heat
93
what is an inflammatory response
events triggered by signalling molecules released upon injury or infection
94
describe the inflammatory response
activated macrophages discharge cytokines
mast cells release histamine at sites of damage
histamine triggers blood vessels to dilate and become more permeable
increase in local blood supply produces redness and increased skin temperature
activated complement proteins promote further release of histamine attracting more phagocytic cells enhanced blood flow and permeability helps deliver antimicrobial peptides and neutrophils
the result is pus
95
what are cytokines
signalling molecules that recruit neutrophils to the site of injury
96
what are mast cells
immune cells found in connective tissue
97
what is histamine
a signalling molecule
98
what is pus
a fluid rich in wbc, dead pathogens and debris from damaged tissue
99
what is the hypothesis regarding fever and infection
increased body temperature may enhance phagocytosis and by speeding up chemical reactions, accelerate tissue repair
100
what adaptations have pathogens evolved that enable them to avoid destruction by phagocytic cells
the outer capsule of bacteria interferes with molecular recognition and phagocytosis
some bacteria are recognised but resist breakdown after being engulfed, they can then grow inside the host cell and be hidden from the immune defences. TB is a result of this
101
what does the adaptive immune response rely on
T cells and B cells which are types of white blood cells called lymphocytes
102
like all blood cells, lymphocytes originate from where
the stem cells in the bone marrow
103
some lymphocytes migrate from the bone marrow to where
the thymus (an organ in the thoracic cavity above the heart)
104
the lymphocytes that migrate to the thymus mature into what
T cells
105
the lymphocytes that remain in the bone marrow develop into what
B cells
106
lymphocytes of a third type remain in the blood and become what
the natural killer cells of both the innate and adaptive immunity
107
any substance that elicits and B or T cell response is called what
an antigen
108
how does recognition occur in adaptive immunity
A B cell or T cell binds to an antigen via a protein called an antigen receptor. infection by a pathogen triggers activation of B and T cells with antigen receptors specific for parts of the pathogen
109
a single lymphocyte produces how many types of antigen receptor
1 - has many of it though
110
antigens are usually proteins or ………..
polysaccharides
111
the small accessible portion of and antigen that binds to the antigen receptor is called what
epitope
112
the antigen receptors of B and T cells have similar components but what do they do differently
they encounter antigens in different ways
113
what shape is a B cell antigen receptor
Y shaped
114
each B cells receptor has how many identical antigen binding sites
2
115
what happens when a B cell antigen receptor binds to an antigen
it is an early step in B cell activation and leads to formation of cells that secrete the soluble form of the receptor, CALLED AN ANTIBODY, also known as immunoglobulin (Ig)
116
is the antibody produced specific to the same epitope as the original B cell
yes
117
what is different about the original B cell receptor and the produced antigen
they have the same y shaped structure but the antibody lacks a membrane anchor
118
B cells receptors and antibodies bind to bind to antigens where
in the blood and the lymph
119
true or false: B cell antibodies can bind to antigens on the surface of pathogens or free in body fluids
true
120
what does the antigen receptor of a T cell consist of
two different polypeptide chains joined by a disulphide bridge. both polypeptides are anchored in the plasma membrane of the T cell
121
what does the antigen receptor of a B cell consist of
two identical non variable light chains and tow identical fixed heavy chains that link together by disulphide bridges. the heavy chains are anchored in the plasma membrane of the B cell
122
what is the difference in the binding of B and T cell receptors to an epitope
the B cells bind to epitopes of intact antigen protruding from pathogens or circulating free in body fluids
the T cells bind only to fragments of antigens that are displayed or presented on the surface of host cells
123
what is a major histocompatibility complex (MHC) molecule
a host protein that displays an antigen fragment on the cell surface
124
what is essential for antigen recognition by T cells
MHC molecules
125
how does antigen recognition by T cells work
pathogen infects an animal cell
inside the cell an antigen fragment of the pathogen binds with an MHC molecule
the MHC molecule with the antigen fragment bound is brought to the cell surface where it is displayed
the combination of MHC molecule and antigen fragment is recognised by the T cell
the interaction triggers an adaptive immune response
126
What part of the MHC antigen fragment complex is the T cell receptor specific for
the antigen fragment
127
what are the four major characteristics of adaptive immunity
1. the large stock of lymphocytes and receptors enables detection of antigens never before encountered
2. adaptive immunity normally has self tolerance (doesn't react with the animals own cells)
3. cell proliferation triggered by activation increases the no. T and B cells specific for an antigen
4. There is a stronger and more rapid response to an antigen encountered previously due to immunological memory
128
assembly of a functional immunoglobin (antibody gene) requires what
rearrangement of DNA
129
which enzyme joins to the immunoglobin gene during formation of a functional antibody
recombinase
130
what happens during the recombination event
a long stretch of DNA is eliminated, leaving behind only the DNA to be transcribed and translated into the functional gene of the antigen receptor
131
how does recombinase act randomly
it connects any part one of the V (variable) gene segments to any one of the J (joining) gene segments
132
after DNA arrangement what is the next step in generation of diverse B and T cells
the rearranged genes are transcribed and translated. The resulting chains then join together forming an antigen receptor
133
why are B and T cells so highly specific
due to DNA arrangement and mutations introduced during the recombinant stage. depends which parts are treated as introns/exons as to what is included
134
some immature lymphocytes produce receptors specific for epitopes on the organisms own molecules . what would happen if these were not eliminated or inactivated
the immune system could not distinguish between self and non self and would attack body proteins, cells and tissues
135
what is tested when lymphocytes are maturing in either the bone marrow or the thymus
they are tested for self reactivity
136
what are the two ways that self reactivity can be eliminated
B/T cells with receptors for the body's own molecules undergo apoptosis or are just rendered non functional
137
as the body normally lacks mature lymphocytes that can react against its own molecules the immune system is said to be what
self tolerant
138
where is the first place that an antigen is presented
to a steady stream of lymphocytes in the lymph node until a match is made
139
a successful match between an antigen receptor and an epitope initiates what
events that activate the lymphocyte bearing the receptor
140
Once B/T cell is activated what happens
it undergoes multiple cell divisions
141
what is produced when the b/T cells proliferate
lots of clones of the original cells
142
some of the cloned cells become what
effector cells
143
what is an effector cell
short lived cells that take effect immediately against antigens and pathogens
144
what are the effector cell forms of B cells
plasma cells which secrete antibodies
145
what are the effector cell forms of T cells
helper T cells and cytotoxic T cells
146
other than effector cells what else can the clone cells become
memory cells
147
what are memory cells
long lived cells that can give rise to effector cells If the same antigen is ever encountered again
148
what is clonal selection
the process by which an antigen selectively binds to and activates only those lymphocytes bearing receptors specific to the antigen. The lymphocytes proliferate into a clone of effector cells and memory cells for that antigen
ANTIGEN SELECTS LYMPHOOCYTE THEN DIVIDES TO PPRODUCE CLONES
149
what does immunological memory provide
long term protection provided by a prior infection e.g. chicken pox
150
prior exposure to an antigen alters which 3 aspects of the immune response
speed, strength and duration
151
the effector cells formed by clones of lymphocytes after initial exposure to an antigen produce what kind of immune response
primary immune response
152
if the same antigen is encountered again what kind of immune response is produced
secondary immune response
153
which immune response is faster, of greater magnitude and prolonged
secondary immune response
154
what does the secondary immune response rely on
the reservoir of T and B memory cells
155
what about the memory cells makes them well adapted for immunological memory
they are long lived (can live for many decades)
156
what do the memory cells do if they encounter the antigen
they form clones generating an enhanced immune defence
157
can humoral and cell mediated immunity include both primary and secondary immune responses
yes
158
what type of cell activates both the humoral and cell mediated response
helper T cell
159
what must happen before a helper T cell can activate either a humoral or cell mediated response
a foreign molecule must be present that can bind specifically to the antigen receptor of the helper T cell
the antigen must be displayed on the surface of an antigen presenting cell e.g. dendritic cell, macrophage or B cell
160
how many classes of MHC cell do body cells have
1
161
how many classes of MHC cell do antigen presenting cells have
2
162
run through the process of helper T cells activating adaptive immunity
helper T cell antigen receptors bind to the antigen fragment and the class 2 MHC molecule displaying the fragment on the antigen presenting cell
CD4 (attached to helper T) binds to the MHC molecule keeping the cells joined
cells interact when cytokines are exchanged (dendritic cell produces cytokines triggering the helper T cell to do the same)
proliferation results in clones that secrete more cytokines, activating B cells (humoral - secretion antibody) and Cytotoxic T cells (cell mediated - infected cell attack)
163
is secretion of antibodies a humoral or cell mediated response
humoral
164
what is involved in B cell activation
helper t cells and proteins on the surface of pathogens
165
what stimulates proliferation of B cells
antigen and cytokines
166
how are macrophages and dendritic cells different to B cells
B cells only presents the antigen that it is specific to
167
what happens when an antigen binds to the B cell receptor
the B cells take in a few of the foreign molecules
168
A class 2 MHC protein of the B cell presents an antigen fragment to what
a helper T cell
169
Cell-cell contact is critical to ….. cell activation
B
170
what does B cell activation lead to
humoral response - plasma cells (effectors) stop expressing the antigen receptor and instead secrete antibodies
171
do antibodies directly kill pathogens
no - they interfere with pathogen activity or mark them for deactivation or destruction
172
what is opsonization
antibodies bound to antigens do not block infection but instead present a structure that promotes phagocytosis
173
what does phagocytosis enable macrophage and dendritic cells to do
present antigens to and stimulate helper T cells which then stimulates the B cells whose antibodies contribute to phagocytosis
174
what are the 5 types of Immunoglobulin produced by B cells
IgA (breastmilk, saliva, tears, blood and airways),
IgM, (blood and lymph)
IgD, (not well understood, lining of abdomen and chest)
IgE (lungs, skin, mucous. common allergies, hay fever), IgG (in blood cross placenta to fetus)
MADGE
175
what is a cytotoxic T cell
a T lymphocyte that kills cancer cells, cells that are infected, or cells that are damaged in other ways
176
how do cytotoxic T cells kill infected host
inject proteins (perforin and granzyme) into the cell that induce cell death (apoptosis)
177
what activates a cytotoxic T cell
helper T cell or antigen presenting cell
178
what is active immunity
the defences that arise when a pathogen infection prompts an immune response
179
what is passive immunity
the short-term immunity which results from the introduction of antibodies from another person or animal. mother and fetus
180
what is a large factor responsible for immune rejection
differences in MHC cells (different in everyone except twins)
181
what is agglutination
when an antibody binds to more than one antigen at a time
182
what is an autoimmune disease
when the immune system is active against particular molecules of the body e.g. lupus, arthritis, multiple sclerosis
183
what is an immunodeficiency disease
a disorder in which an immune system response to antigens is defective or absent e.g. AIDS
184
what is antigenic variation
mechanism by which a pathogen alters its surface proteins in order to evade a host immune response. why flu vaccine need renewed
185
what is latency
in latency the production of most viral proteins and free viruses ceases so they don't trigger an adaptive immune response. the viruses wait until the environment is more favourable for their survival before reactivating
186
which pathogen causes AIDs
HIV
