anatomy of the immune system Flashcards
(103 cards)
1
Q
What percentage of white blood cells (WBCs) are lymphocytes?
A
Lymphocytes make up 20-40% of white blood cells (WBCs).
2
Q
What are the two main types of lymphocytes involved in Adaptive Immunity?
A
The two main types of lymphocytes are B cells and T cells.
3
Q
What is the role of B cells in Adaptive Immunity?
A
B cells make antibodies and constitute approximately 23% of lymphocytes.
4
Q
What are the two main types of T cells in Adaptive Immunity?
A
The two main types of T cells are CD8+ Cytolytic T cells and CD4+ Helper T cells.
5
Q
What percentage of lymphocytes are CD8+ Cytolytic T cells?
A
CD8+ Cytolytic T cells make up approximately 20% of lymphocytes.
6
Q
What percentage of lymphocytes are CD4+ Helper T cells?
A
CD4+ Helper T cells constitute approximately 45% of lymphocytes.
7
Q
What are Gamma delta T cells, and what percentage of lymphocytes do they represent?
A
Gamma delta T cells are a minor population of T cells involved in both innate and adaptive immunity, making up approximately 5% of lymphocytes.
8
Q
Where are T cells produced and selected
A
T cells are produced in the bone marrow and selected in the thymus.
9
Q
How do T cells exit the thymus?
A
T cells exit the thymus through the lymphatic system.
10
Q
What is the function of the lymphatic system?
A
The lymphatic system drains the periphery towards lymph nodes, where immune responses are coordinated.
11
Q
What is found in lymph nodes?
A
Lymph nodes are aggregates of T cells, B cells, and antigen-presenting cells (APCs). They act as headquarters for deciding when and where immune responses need to occur.
12
Q
Where are lymph nodes most concentrated in the body?
A
Lymph nodes are concentrated around the nose, mouth, lungs, and gut, as most infections are inhaled or swallowed.
13
Q
Are lymph nodes only found around the respiratory and digestive systems?
A
No, other nodes are spread throughout the body to help coordinate immune responses.
14
Q
What are the main entry and exit points of lymph nodes?
A
Lymph nodes have various entry and exit points, including an artery and vein for blood supply and lymphocyte entry via high endothelial venules (HEVs). The main entry is through afferent lymphatic vessels.
15
Q
What is the primary function of afferent lymphatic vessels?
A
Afferent lymphatic vessels bring inflow from the lymphatics into the lymph nodes.
16
Q
What does the germinal center of a lymph node house?
A
The germinal center (yellow) houses B cells.
17
Q
Where are T cells primarily found in the lymph node?
A
T cells are mainly found in the paracortical area (blue) of the lymph node.
18
Q
What is the function of the parafollicular area in the lymph node?
A
The parafollicular area is the interface where T cells and B cells communicate with each other.
19
Q
What is found in the medullary cords of a lymph node?
A
The medullary cords (orange) house antibody-producing plasma cells and macrophages.
20
Q
What is the first step in the interaction within lymph nodes?
A
Dendritic cells circulate through the body via blood and lymphatics, carrying antigens.
21
Q
How does a dendritic cell enter a lymph node?
A
A dendritic cell enters the lymph node via the afferent lymphatics, bringing antigens to the lymph node.
22
Q
Where do B cells, T cells, and dendritic cells interact in the lymph node?
A
The interaction between B cells, T cells, and the antigen-laden dendritic cells occurs in the follicular region of the lymph node.
23
Q
How do B cells and T cells interact with antigens in the lymph node?
A
B cells can present antigens to T cells, and dendritic cells can present antigens to both B cells and T cells, leading to activation.
24
Q
What happens after T cells provide help to B cells in the lymph node?
A
After receiving help from T cells, both T cells and B cells can leave the lymph node via the efferent lymphatics to spread throughout the body.
25
What are the two key areas of the spleen?
Red pulp – where RBCs are broken down or produced.
White pulp – where B cells, T cells, and APCs interact.
26
What is the role of Peyer’s Patch in the immune system?
Peyer’s Patch is an organised structure in the gut where dendritic cells can extend pseudopods into the gut to sample antigens and potentially interact with T cells and activate B cells for antibody production.
27
What is the role of M-cells in Peyer’s Patch?
M-cells are specialised APCs that can present antigens either directly or indirectly (via dendritic cells) to T cells.
28
How do dendritic cells in Peyer’s Patch sample antigens?
Dendritic cells in Peyer’s Patch can extend pseudopods through the gut lining to sample antigens from the gut environment.
29
How do dendritic cells (DCs) enter the lymph node?
DCs enter the lymph node via afferent lymphatics.
30
How do T cells enter the lymph node?
T cells enter the lymph node via high endothelial venules (HEVs).
31
What happens to T cells that recognize antigen in the lymph node?
T cells that recognize antigen leave the lymph node via efferent lymphatics.
32
What happens to T cells that do not recognize antigen in the lymph node?
T cells that do not recognize antigen leave the lymph node via the cortical sinuses
33
Where do lymphocytes respond to antigen?
Lymphocytes respond to antigen in peripheral lymphoid organs such as the lymph nodes, spleen, and Peyer’s patches. These organs act as sites for antigen capture and immune cell activation.
34
What must lymphocytes do after responding to antigen?
After recognizing an antigen in the peripheral lymphoid organs, lymphocytes must exit via efferent lymphatics or venous blood and migrate to the effector site, where they carry out immune responses like pathogen destruction or antibody production.
35
How do dendritic cells (DCs) initiate lymphocyte recirculation following infection?
Dendritic cells (DCs) capture antigens at the infection site and migrate through the afferent lymphatics to the lymph node, where they present antigens to naïve T cells, initiating an adaptive immune response.
36
What interaction occurs in the lymph node between DCs and T cells
In the lymph node, DCs present processed antigen fragments on MHC molecules to naïve T cells. This activates antigen-specific T cells, which proliferate and differentiate into effector T cells.
37
What is the role of DCs and T cells in the activation of the adaptive immune response?
DCs presenting antigens activate T helper cells (CD4+) and cytotoxic T cells (CD8+) in the lymph node. T helper cells provide support to B cells for antibody production, while cytotoxic T cells target and kill infected cells.
38
How do lymphocytes exit the lymph node?
After activation, T and B lymphocytes leave the lymph node via efferent lymphatics. Effector T cells then enter the bloodstream and travel to infection sites. Non-activated T cells leave the node through cortical sinuses and continue recirculating.
39
How do lymphocytes return to the bloodstream after leaving the lymph node?
Once activated in the lymph node, lymphocytes enter the efferent lymphatics, which drain into the thoracic duct. From there, lymphocytes re-enter the bloodstream, allowing them to circulate and reach the site of infection.
40
How do DCs interact with T cells after migrating to the lymph node?
After entering the lymph node, DCs present antigens to T cells in the paracortical area, where T cell activation occurs. Activated T cells then move toward effector sites via the bloodstream
41
What happens if T cells do not recognize antigen in the lymph node?
if T cells do not recognize any antigen presented by DCs, they leave the lymph node via the cortical sinuses and continue their recirculation through the blood and lymphatic system.
42
What is the final destination of activated T cells?
Activated T cells migrate to effector sites, which can include sites of infection or tissue injury, where they carry out their immune functions, such as cytotoxic activity or cytokine release to coordinate the immune response.
43
What initiates innate immune responses?
Innate immune responses are initiated by the recognition of pathogens through Pattern Recognition Receptors (PRRs) that detect Pathogen-Associated Molecular Patterns (PAMPs).
44
What are common examples of PAMPs?
Common PAMPs include lipopolysaccharides (LPS) from bacterial cell walls, peptidoglycan, viral RNA, and flagellin
45
What are the key types of PRRs in the innate immune system?
Toll-Like Receptors (TLRs)
NOD-Like Receptors (NLRs)
RIG-I-Like Receptors (RLRs)
C-type Lectin Receptors (CLRs)
46
How does recognition of PAMPs trigger immune responses?
Recognition activates immune cells to release cytokines and chemokines, triggering inflammation, cell recruitment, and complement activation.
47
What is the role of cytokines in the inflammatory response?
Cytokines modulate the immune response, promoting inflammation and activating immune cells (e.g., TNF-α, IL-1, interferons).
48
What do chemokines do during an immune response?
Chemokines attract immune cells to the site of infection, guiding their migration and tissue infiltration.
49
What are the functions of the complement system?
Opsonization of pathogens
Formation of the Membrane Attack Complex (MAC)
Promotion of inflammation
Clearance of immune complexes
50
What are Pattern-Recognition Receptors (PRRs)?
PRRs are receptors in the innate immune system that detect specific molecules from pathogens or damaged cells, initiating an immune response.
51
What are Pathogen-Associated Molecular Patterns (PAMPs)?
PAMPs are distinct molecular motifs found in many pathogens that are not present in eukaryotic cells, enabling the immune system to recognize and respond to them.
52
How do PAMPs trigger the immune response?
PAMPs are recognized by PRRs, which leads to the activation of immune cells, production of cytokines, and the initiation of inflammatory responses.
53
What are Damage-Associated Molecular Patterns (DAMPs)?
DAMPs are molecules expressed by damaged or dying host cells that signal to the immune system, indicating the presence of tissue injury.
54
How do DAMPs differ from PAMPs?
DAMPs are derived from the host's own cells in response to injury, while PAMPs are derived from pathogens and are recognized as foreign by the immune system.
55
Why are PRRs important in the immune response?
PRRs enable the innate immune system to quickly detect and respond to both pathogens (via PAMPs) and tissue damage (via DAMPs), facilitating a rapid immune response.
56
Give an example of a PAMP.
Lipopolysaccharides (LPS) found in the outer membrane of gram-negative bacteria are a common example of PAMPs.
57
What role do DAMPs play in inflammation?
DAMPs can promote inflammation and recruit immune cells to the site of injury, enhancing the body's healing process.
58
What are Toll-like Receptors (TLRs)?
TLRs are a type of pattern recognition receptor that are most studied; they recognize leucine-rich repeat motifs and detect various pathogens including viruses, bacteria, fungi, and damaged cells.
59
What is the main function of TLRs?
TLRs function to recognize specific patterns on pathogens, triggering immune responses to help eliminate infections.
60
What do C-type lectin receptors (CLR) recognize?
CLRs recognize carbohydrates, such as mannose, and are involved in detecting viruses, bacteria, fungi, parasites, and cancer cells.
61
How do C-type lectin receptors (CLR) contribute to the immune response?
CLRs bind to carbohydrate structures on pathogens, facilitating phagocytosis and triggering signaling pathways that activate immune cells.
62
What do NOD-like receptors (NLR) primarily recognize?
NLRs recognize peptidoglycans, which are components of bacterial cell walls.
63
What role do NOD-like receptors (NLR) play in immunity?
NLRs detect bacterial components and activate inflammatory responses, contributing to the defense against bacterial infections.
64
Which type of receptor is primarily involved in recognising viral, bacterial, and fungal pathogens?
Toll-like Receptors (TLRs) are primarily involved in recognizing viral, bacterial, and fungal pathogens.
65
Can you name a type of pattern recognition receptor that detects carbohydrates?
C-type lectin receptors (CLR) are a type of pattern recognition receptor that detects carbohydrates.
66
What types of pathogens can NOD-like receptors (NLR) recognise?
NLRs primarily recognise bacterial pathogens by detecting peptidoglycans.
67
What are the two main locations where Toll-like Receptors (TLRs) are found?
TLRs are found as either endosomal or plasma membrane transmembrane receptors.
68
What are the two main components of the TLR structure?
TLR structure consists of a leucine-rich pathogen recognition domain and a signaling domain.
69
What is the function of the leucine-rich pathogen recognition domain in TLRs?
The leucine-rich pathogen recognition domain allows TLRs to recognize specific patterns on pathogens, initiating immune responses.
70
What role does the signaling domain of TLRs play?
The signaling domain of TLRs transmits signals into the cell upon pathogen recognition, leading to the activation of immune responses.
71
How do TLRs contribute to the innate immune response?
By recognising pathogen-associated molecular patterns (PAMPs) through their structure, TLRs trigger signaling pathways that activate immune cells and promote inflammation.
72
Are TLRs specific to certain pathogens or do they recognise a broad range of pathogens?
TLRs recognise a broad range of pathogens by detecting conserved motifs (PAMPs) shared among different microorganisms.
73
What is one major consequence of Toll-like Receptor (TLR) stimulation?
The major consequence is the activation of phagocytic cells.
74
What do phagocytic cells secrete upon activation by TLR stimulation?
Phagocytic cells secrete cytokines and chemokines.
75
What is the effect of cytokine and chemokine secretion by phagocytic cells?
It recruits more phagocytes to the site of infection and triggers inflammation.
76
How does TLR stimulation affect phagocytosis?
TLR stimulation enhances phagocytosis, allowing phagocytes to engulf and destroy pathogens more effectively.
77
What intracellular processes are triggered by TLR stimulation in phagocytic cells?
TLR stimulation triggers intracellular killing mechanisms to eliminate engulfed pathogens.
78
What is the relationship between TLR stimulation and inflammation?
TLR stimulation triggers the release of inflammatory mediators, contributing to the inflammatory response.
79
What are cytokines?
Cytokines are small (5-20 kDa) hormone-like secreted proteins that play key roles in immune responses.
80
What are the different types of cytokines?
Cytokines include chemokines, interferons, interleukins, lymphokines, and tumor necrosis factors.
81
How do cytokines exert their effects?
Cytokines act through specific cell surface receptors on target cells.
82
In what biological processes are cytokines important?
Cytokines are important in host immune responses to infection, inflammation, trauma, sepsis, cancer, and reproduction.
83
What is the role of chemokines within the family of cytokines?
Chemokines are a subset of cytokines that specifically mediate the chemotaxis of immune cells to sites of infection or inflammation.
84
What is the function of interferons in the immune response?
Interferons are cytokines that inhibit viral replication and enhance the immune response against pathogens.
85
What are interleukins primarily involved in?
Interleukins are involved in communication between leukocytes and play roles in regulating immune responses.
86
What is the primary function of cytokines in the immune system?
Cytokines facilitate communication between cells, enabling the activation of appropriate cells to destroy invading pathogens.
87
How do cytokines affect the movement of target cells?
Cytokine interactions can change the expression of adhesion molecules and chemokine receptors on target cells, allowing them to move to different locations.
88
Can cytokines influence cell survival?
Yes, cytokines can instruct target cells to undergo programmed cell death, or apoptosis.
88
What effect can cytokines have on enzyme activity in target cells?
Cytokines can instruct target cells to increase or decrease enzyme activity, affecting various cellular functions.
89
How do cytokines contribute to the immune response?
By regulating the behavior and activity of immune cells, cytokines help coordinate the immune response to infections and other challenges.
90
What role does IL-1 play in the immune system?
IL-1 is a cytokine that promotes inflammation.
91
What is the function of TNF-alpha in innate immunity?
TNF-alpha is a cytokine involved in inflammation and the regulation of immune cells.
92
How does IL-12 influence the adaptive immune response?
L-12 is a cytokine that influences the differentiation of T cells and enhances the activity of natural killer (NK) cells.
93
What is the role of IL-6 in the immune system?
IL-6 is a cytokine that influences adaptive immunity and promotes inflammation.
94
What function do interferons serve in innate immunity?
interferons are antiviral cytokines that inhibit viral replication in host cells.
95
What are chemokines?
Chemokines are a subpopulation of cytokines that act as chemoattractants, specifically causing immune cells to move toward sites of infection or inflammation.
96
What is the primary function of chemokines in the immune response?
The primary function of chemokines in the immune response is to attract immune cells to the site of infection, aiding in the recruitment of cells necessary for pathogen clearance.
97
What distinguishes chemokines from other cytokines?
Chemokines are specifically involved in the movement of immune cells, whereas other cytokines may have various roles in cell signaling, activation, and communication.
98
What are some examples of chemokines?
Examples of chemokines include IL-8, CCL19, CCL21, RANTES, CCL2 (MCP-1), and CCL3 (MIP-1 alpha).
99
How do chemokines contribute to the innate immune response?
Chemokines contribute to the innate immune response by guiding phagocytes and other immune cells to the location of infection, facilitating an effective immune response.
100
What are the potential outcomes of chemokine signaling in immune cells?
Chemokine signaling can lead to various outcomes in immune cells, such as changes in adhesion molecule expression, migration to infection sites, and enhanced activation of immune responses.
101
What role does IL-8 play among chemokines?
L-8 is a chemokine that acts as a powerful attractant for neutrophils, promoting their migration to sites of infection.
102
How do chemokines impact the effectiveness of the immune response?
By effectively directing immune cells to infection sites, chemokines enhance the overall effectiveness of the immune response, improving the body’s ability to clear pathogens.
