Module 5: Immunology Flashcards
(139 cards)
1
Q
Three components of the immune system
A
Organs
Cells
Molecules
2
Q
Immune system
A
Organised system of organs cells and molecules that interact together to defend the body against disease
3
Q
What kind of diseases can the immune system affect? (3)
A
Infectious
Inflammatory
Cancer
4
Q
Primary lymphoid organs (2)
A
Thymus
Bone marrow
(Produce white blood cells/ lymphocytes)
5
Q
Secondary lymphoid organs (3)
A
Tonsils
Spleen
Lymph nodes
Sites where immune responses are initiated
6
Q
What occurs in the bone marrow?
A
Stem cells are sourced
They develop into cells of the innate and adaptive immune responses
7
Q
What occurs in the thymus?
A
Developing T cells learn not to react to self (school)
8
Q
What occurs in the spleen?
A
Initiation of immune responses against blood-borne pathogens
9
Q
What occurs in the lymph nodes? (2)
A
Lymph fluid is filtered from blood and tissue
Immune responses are initiated
10
Q
Three layers of defence of the immune system
A
Chemical and physical barriers
Innate arm
Adaptive arm
11
Q
Which is slower to take action- innate or adaptive arm?
A
Adaptive
12
Q
Physical barrier for the immune system
A
Skin
13
Q
Two layers of the skin, what do they contain?
A
Epidermis- dead cells, keratin and phagocytic immune cells
Dermis- thick layer of connective tissue, collagen, blood vessels and phagocytic immune cells
14
Q
What do phagocytic immune cells do?
A
Engulf and kill microbes
15
Q
Dendritic cells
A
Immune cells in the skin
Have dendritic arms that give big surface area which is good for communication between innate and adaptive arms
16
Q
Chemical defenses of the skin (4)
A
Antimicrobial peptides (e.g. defending which form pores in microbial cell membranes)
Lysozyme- breaks down bacterial cell walls
Sebum- low pH so microbes can’t grow
Salt- hypertonic dries out microbes
17
Q
Where are sebum and salt secreted?
A
Sebaceous gland and sweat gland
18
Q
Where are mucous membranes present? (4)
A
Inner body parts that come into contact with the air
Eyes
Respiratory tract
GI tract
Genital/rectal tract
19
Q
Three components of mucous membranes
A
Mucus layer
Epithelium
Fibrous connective tissue (lamina propria)
20
Q
Where are goblet cells, and what do they produce?
A
Epithelium
Mucus
21
Q
Direction and function of mucociliary escalator
A
Up to pharynx
Cilia move dust and trapped microbes up to be swallowed- which get destroyed in the gut
22
Q
What other cells accompany goblet cells in the epithelium?
A
Columnar cells
23
Q
Chemical defences of mucosal surfaces (6)
A
Stomach- low pH (breaks down microbes)
Gall bladder- bile (antimicrobial)
Intestine- digestive enzymes (break down microbes)
Mucus (transports microbes away)
Defensins (antimicrobial peptides)
Lyzozyme- tears, urine (break down cell walls)
24
Q
Which has more cell layers- skin or mucous membranes?
A
Skin
25
Which contains alive cells- mucous membranes or skin?
Both
Skin also contains dead cells in outer layers
26
Why is sebum present in the skin, but not in mucous membranes?
Because there are hairs on the skin to which it’s attached
27
In which tubes are cilia present on mucous membranes?
Trachea and uterine tubes
28
How do innate and adaptive arms communicate?
Through dendritic cells
29
Innate internal defenses (5)
```
Phagocytes
Natural killer cells (kill virus-infected cells)
Inflammation
Antimicrobial proteins
Fever
```
30
Two cells of the adaptive defense and their functions
B cells- make antibodies
T cells- produce chemical messengers and become killer cells
31
Which arm of the immune system can discriminate between viruses, and even strains of a virus?
Adaptive arm
32
Which has a long-term specific memory: adaptive or innate arm?
Adaptive (innate has no specific memory)
33
What can the innate arm detect if it can’t discriminate between viruses?
Molecular components
- cell wall components
- nucleic acids
Etc.
34
Two general components of blood
Plasma (55%)
| Cells (45%)
35
What does plasma include?
Proteins
Water
Other solutes
36
Which three cells make up the 45% formed elements in the blood?
Platelets
White blood cells
Red blood cells
37
Name for white blood cells
Leukocytes
38
Where are blood cells sourced, and what is this process called?
From the bone marrow
| Hematopoiesis
39
Hematopoietic cells
What three lineages derive from them?
Stem cells that develop into blood cells
Erythropoietin
Myeloid
Lymphoid
40
Erythroid lineage
Red blood cells (erythrocytes) derived from hematopoietic stem cells
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Four innate immune cells
Which lineage are these?
Granulocytes, monocytes, dendritic cells, platelets
| Myeloid lineage
Derived from hematopoietic stem cells
42
Adaptive immune cells
What lineage do they come from?
B and T lymphocytes
Lymphoid lineage
43
Which two lineages are white blood cells?
Myeloid and lymphoid
44
Granulocyte in blood
Neutrophil
46
Neutrophils
Granulocyte in the blood which makes up 75% of all leukocytes
Highly phagocytic
47
Granulocyte in tissue
Mast cells
48
Where are mast cells found?
Lining mucosal surfaces
49
How do mast cells attract white blood cells to areas of tissue damage?
By releasing granules which acts as a signal
50
Two types of phagocytic cells
Where are they present?
Monocytes- blood- low phagocytosis
Macrophages- tissues- high phagocytosis
51
How are monocytes related to macrophages?
Monocytes develop into macrophages when they leave the blood
52
Macrophages can be sessile or migratory- what does this mean?
They can become resident or move through tissues
53
Three functions of macrophages
Phagocytosis
Release of chemical messengers
Show information about pathogenic microbes to T cells (linking arms)
54
Which is the most important cell to help trigger adaptive immune responses?
Dendritic cells
55
How do cells of the immune system move around the body?
Leave blood to enter tissues
Carried in the lymph which is drained into lymph nodes
56
PAMPS
Pathogen-associated molecular patterns
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Three components to a virus PAMP
Nucleic acid (ssRNA or dsRNA)
Nucleocapsid (protein)
Envelope (sometimes)
58
Five components of a bacterium PAMP
```
Nucleic acid
Cell membrane
Cell wall
Capsule (sometimes)
Flagella
```
59
Building blocks of flagella
Flagellin
60
What kind of nucleic acid is commonly present in bacteria?
Unmethylated CpG DNA
61
Common building blocks of bacterial cell wall (3)
LPS (lipopolysaccharide)
Endotoxins
Lipoteichoic acid
62
How does a phagocytic cell recognise microbes?
Through its PRRs (pattern recognition receptors)
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What components of microbes do PRRs recognise?
Bacterial cell wall components
| Yeast cell wall components
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What do PRRs do once they recognise components of a microbe?
Send a signal to the phagocytic cell nucleus to regulate gene transcription
Makes lots of proteins to fight specific microbe
65
Pyrexia
Fever
66
What is released by immune cells during fever?
Pyrogens
67
IL-1
Interleukin-1
Produced by phagocytes after ingesting bacteria
68
Why is fever useful?
Decreases phagocytosis
Which decreases IL-1
Which decreases temperature
69
When do numbers of neutrophils in blood increase? Why?
During infection
Granulocytes circulate in the blood and move into tissue during inflammation
70
How do dendritic cells link the innate and adaptive?
Drain into lymphatic vessels to lymph nodes
Where they activate T and B cells
71
B cells produce _____
Antibodies
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Antibodies do: (2)
Label bacteria for phagocytosis
| Block interaction between bacterial cell and receptor
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What do cytotoxic T cells do?
Send death signals
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Where are dendritic cells present?
In major organs
Mostly in skin
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What do dendritic cells do when they come across an antigen?
Phagocytose it and process it down to peptides- then present it on MHC to T cells
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If dendritic cells are in the blood, where do they migrate to after phagocytosing an antigen?
The spleen
77
Antigen
Anything that has the potential to be recognised by the immune system
78
Auto-antigen
Self-antigen
Protein made by our own cells (usually immune system is tolerant of these)
79
APC (3)
Antigen presenting cell- any cell that can present antigens to T cells
- macrophages
- dendritic cells
- B cells
80
Two types of T cells
CD8
| CD4
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What does CD4 do? (2)
Helps CD8
| Activates B cells
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What do B cells do once activated?
Differentiate into plasma cells
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What do plasma cells do? Where are they found?
Make lots of antibodies
Lymph nodes and spleen
84
What does CD8 become when presented with an antigen?
CTL (killer cell) which kills virus-infected cells
85
How do CTL cells kill virus infected cells?
Sending killer signal (peforin/ granzyme)
86
MHC
Major histocompatibility complex (I and II)
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TCR
T cell receptor
88
Where on the APC and T cell is the antigen presented?
On the MHC
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Which MHC do CD8 cells recognise?
MHC-1
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MHC-II is recognised by which T-cell?
CD4
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What about their immune systems separate vertebrates and invertebrates?
Invertebrates only have innate immunity
92
Endogenous antigen
An antigen which lives inside the cell (eg virus)
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Exogenous antigen
An antigen which enters the cell when its phagocytosed
94
Which cells express MHC-I? Why?
MHC-I presents endogenous antigens
All unnucleated cells have MHC-I
95
Which cells express MHC-II as well as MHC-I? Why?
Antigen-presenting cells (APC) because MHC-II presents exogenous antigen
96
Describe MHC-I antigen processing (3)
Antigen proteins are degraded to peptides in cytoplasm
Peptides are imported into ER
In the ER, peptides are loaded on MHC-I
97
Describe MC-II antigen processing (3)
Antigen proteins are degraded in an acidic phagolysosome
Peptides are loaded on MHC-II in phagolysosome
MCH-11 and peptide travel to cell membrane
98
T cells proliferate when activated by APCs. What does this mean?
They make more of themselves
99
Two examples of endogenous antigens
Viral proteins produced during viral replication
Proteins produced by intracellular bacteria
100
Examples of exogenous antigens (3)
Fungi
Bacteria
Parasites
101
What property of a phagolysosome breaks down exogenous antigens?
It’s acidity
102
What three things occur in the thymus?
Creates a pool of T cells that can recognise antigens
Gets rid of T cells that recognise self antigens
TCR gene rearrangement
103
What is the purpose of TCR gene rearrangement?
Each T cell has a TCR specific for one antigen
104
Naive T cell
A T cell that has undergone TCR gene rearrangement, but hasn’t carried out immune response
105
Thymocyte
Immature T cell - hasn’t undergone TCR gene rearrangement
106
Coreceptors on CD4 and CD8 cells
Function
CD4 and CD8
Stabilises interaction between MHC/peptide and TCR
107
Which T cell makes cytokines? What do these do?
CD4
Cytokines are soluble messengers which support other immune cells
108
Other name for CD4 cells
Helper T cells
109
Which T cell makes cytotoxic molecules?
CD8
110
Name two cytotoxic molecules
Perforin
| Granzyme
111
What do cytotoxic molecules do?
Kill infected cells
112
What cell can CD8 cells develop into once activated?
Cytotoxic T lymphocytes (CTL)
113
Effector T cells and their functions (4)
Activated T cells
Kill infected cells
Make cytokines
Support antibody production
Remember the antigen for next time
114
How does a CTL know which cells to kill?
They will express the peptide on MHC-1 on their cell surface that the CTL has the TCR for
115
Memory T cells
CD4 or CD8 cells that reside in the body for long periods of time
They have been activated before, and can be activated much quicker than naive cells
116
Which concept/ science is based on the function of memory cells?
Vaccination
117
HIV infection leads to loss of ______
CD4 T cells
118
Which cells does CD4 help to activate?
CD8 and B cells
119
Where are B cells made?
Bone marrow
120
BCR
B cell receptor
121
Two parts of antibody
Heavy chains and light chains
122
An antibody is a secreted ____
BCR
123
What is different about the way T cells and B cells recognise antigens?
B cells don’t need MHC to recognise it
124
Functions of antibody (3)
NOC
Neutralisation
Opsonisation
Complement activation
125
Describe viral neutralisation
Antibodies coat virus so it can’t attach to receptor on host cell
This neutralises virus activity
126
What is the name of the process that makes bacteria tastier for macrophages?
Opsonisation (antibodies bind)
127
Describe complement activation
Antibodies bind to host cell
Complement proteins can bind to the antibodies
It activates complement pathway to destroy pathogen more quickly
128
Five antibody isotypes
```
IgM
IgG
IgA
IgE
IgR
```
129
Describe IgM and it’s function
Pentamer antibody with J chain
First Ig class produced after initial exposure to antigen
Expressed on naive B cells and acts as BCR
Very effective in activating complement
Targets extra cellular bacteria
130
Describe IgG and it’s function
Monomer antibody
Most abundant Ig class in blood
Opsonises/ neutralises
Only Ig class that can cross the placenta
Targets virus and bacteria
131
Passive immunity
Acquired immunity of fetus from mother through placenta
132
Describe IgA and it’s function
Dimer antibody with secretory component and J chain. Exists in monomeric form in blood (more stable as dimer in secretory areas)
Present in secretions incl breast milk
Defends mucosal membranes
Targets virus and bacteria
133
Describe IgE and it’s function
Monomer antibody
Present in blood at low concentrations
Activates mast cells by binding them to parasites
Causes allergic reactions
134
IgD and it’s function
Monomer antibody
Expressed on naive B cells
Function unknown but can act as BCR
135
What happens to the B cells that are stimulated, but don’t differentiate into plasma cells?
They form a pool of memory cells
136
Where are memory cells found?
In blood and lymph
137
Do memory B cells secrete antibody?
No, but they express it as BCR
138
What happens if a memory B cell sees the same antigen for a second time?
Becomes plasma cells and secretes antibody
139
Primary immune response
Involves naive B cells
Takes 7-14 days to produce sufficient antibody to eliminate pathogen
Mainly IgM
140
Secondary immune response
Relies on memory B cells
Takes 2-3 days to produce sufficient antibody to eliminate pathogen
Mainly IgG
Higher amounts of antibodies produced
