Exam 3 Flashcards
(113 cards)
1
Q
What is the primary function of the immune system?
A
To protect the body from harmful microbes called pathogens.
Pathogens include bacteria, viruses, fungi, and parasites.
2
Q
What are immune cells?
A
Cells that travel throughout the body through blood vessels and lymphatic vessels to protect against pathogens.
3
Q
Name the key lymphoid organs involved in the immune system.
A
- Bone marrow
- Lymph nodes
- Spleen
- Thymus
- Tonsils
4
Q
What physical barrier helps prevent pathogen entry into the body?
A
The skin, which covers the outside of the body.
5
Q
What role does mucus play in the immune system?
A
It traps pathogens in the mucous membranes of the digestive and respiratory systems.
6
Q
How does saliva and sweat contribute to the immune response?
A
They contain antibodies and enzymes that destroy pathogens.
7
Q
What is the function of stomach acid in the immune system?
A
It kills many pathogens in food and drink.
8
Q
What is the role of bone marrow in the immune system?
A
It is where both red blood cells and immune cells develop from blood stem cells.
9
Q
What types of progenitor cells are produced in the bone marrow?
A
- Lymphoid progenitors
- Myeloid progenitors
10
Q
Which immune cells develop fully in the bone marrow?
A
B cells.
11
Q
Where do T cells develop?
A
In the thymus.
12
Q
What are T cell receptors (TCRs)?
A
Proteins produced by T cells that bind to antigens from pathogens.
13
Q
What happens to T cells that bind to self-antigens?
A
They are destroyed to prevent autoimmune responses.
14
Q
What is the function of lymph nodes?
A
They filter lymph and are sites where immune cells target pathogens.
15
Q
What is the main function of the spleen?
A
To remove old or damaged cells from the blood.
16
Q
What are the two main parts of the immune response?
A
- Innate immune response
- Adaptive immune response
17
Q
What is the innate immune response?
A
The body’s immediate and broad protection against pathogens.
18
Q
What are the first responders in the innate immune response?
A
Phagocytes, including neutrophils and macrophages.
19
Q
What is phagocytosis?
A
The process by which phagocytes engulf and destroy pathogens.
20
Q
What triggers inflammation during an infection?
A
The encounter of pathogens with mast cells and macrophages.
21
Q
What is histamine’s role in inflammation?
A
It makes blood vessels leaky to allow immune cells and fluid to enter tissues.
22
Q
What are cytokines?
A
Small proteins released by macrophages that attract more immune cells and activate them.
23
Q
What is a cytokine storm?
A
An excessive production of cytokines that can lead to tissue and organ damage.
24
Q
What is the role of natural killer (NK) cells?
A
To recognize and destroy abnormal cells, including infected and cancer cells.
25
How do antigen-presenting cells function?
They display antigens on their surface using MHC proteins to activate T cells.
26
What is the significance of dendritic cells in the immune response?
They are the most common antigen-presenting cells that activate T cells.
27
What is the adaptive immune response?
The adaptive immune response is a specific and powerful response that targets antigens from specific pathogens and abnormal cells.
28
How does the adaptive immune response differ from the innate immune response?
The adaptive immune response is more specific and powerful, and it can remember previously encountered pathogens.
29
What are the two main parts of the adaptive immune response?
* Cell-mediated immune response controlled by activated T cells
* Humoral immune response controlled by activated B cells
30
What must occur for T cell activation?
A T cell must encounter an antigen-presenting cell displaying a matching antigen on its MHC proteins.
31
What happens once a T cell is activated?
The T cell divides rapidly and produces many identical T cells with the same TCR.
32
What types of T cells can be activated?
* Helper T cells
* Cytotoxic T cells
33
What role do helper T cells play?
Helper T cells activate other immune cells, such as B cells and cytotoxic T cells.
34
What do cytotoxic T cells do?
Cytotoxic T cells destroy cells infected with a pathogen by inducing apoptosis.
35
What is the duration for T cell activation?
T cell activation takes approximately 12 hours.
36
What is the process by which the body produces antibodies called?
The humoral immune response.
37
What happens once a B cell binds to an antigen?
The B cell can be activated by a helper T cell, multiply, and differentiate into plasma cells that produce antibodies.
38
How do antibodies help the body fight pathogens?
* They bind to antigens on pathogens, causing clumping.
* They neutralize toxins produced by pathogens.
* They activate complement proteins.
39
What is the duration for antibody production?
Antibody production takes approximately 6 days.
40
What are memory cells?
Memory cells are activated B and T cells that remain in the body at low levels and can respond quickly to future infections with the same pathogen.
41
How long do memory cells last after an infection?
Memory cells can last for years and allow for a faster immune response upon re-infection.
42
What is a secondary immune response?
The secondary immune response is a faster and stronger reaction that occurs when the same pathogen infects the body again.
43
upon re-infection, memory T cells differentiate into?
Memory T cells differentiate into helper T cells and cytotoxic T cells that respond to the pathogen.
44
What is the main function of memory B cells?
Memory B cells differentiate into plasma cells that produce antibodies upon re-infection.
45
What immune cells are involved in the innate immune response?
* Phagocytes
* Natural killer (NK) cells
* Inflammatory cells (mast cells, eosinophils)
46
How quick is the innate immune response?
The innate immune response is immediate but less powerful.
47
Does the innate immune response have memory?
No, the innate immune response does not remember pathogens.
48
How does the adaptive immune response 'remember' pathogens?
The adaptive immune response produces memory cells that mount a faster and more powerful response to returning pathogens.
49
The adaptive immune response has two main parts:
the cell-mediated immune response, which is controlled by activated T cells
the humoral immune response, which is controlled by activated B cells.
50
the cell-mediated immune response is:
The processes by which T cells are activated and cytotoxic T cells destroy infected cells
51
A decrease in T cells would most directly reduce the immune system’s ability to:
One of these :
* launch an innate immune response
*
:
kill cells infected with a pathogen
*
:
produce antigen-presenting cells
*
:
destroy B cells
kill cells infected with a pathogen
52
A humoral response involves the:
production of antibodies by plasma cells
53
In the secondary response, memory B cells differentiate into
plasma cells that make antibodies.
54
Which of the following statements most accurately compares the primary and secondary immune responses to a specific pathogen?
* The secondary immune response involves more innate immune cells than the primary immune response does.
* Innate immune cells are only involved in the primary immune response.
* The secondary immune response takes longer than the primary immune response.
* The secondary immune response produces many more antibodies than the primary immune response does.
The secondary immune response produces many more antibodies than the primary immune response does.
55
The body has physical and chemical barriers to keep pathogens from infecting, or entering, tissues. These barriers include:
* The skin, which covers the outside of the body. The outer layer of the skin is made of dead cells that block pathogens.
* Sticky mucus, which traps pathogens. Mucus covers the cells of the mucous membranes: layers of cells that line the inside of the digestive system (gut) and respiratory system (airways). Some cells in the respiratory system have moving “hairs” that sweep mucus and trapped pathogens out of the body.
* Saliva and sweat, which contain antibodies and enzymes that destroy pathogens.
* Stomach acid, which kills many of the pathogens in what we eat or drink.
56
Lymphoid progenitors produce:
Myeloid progenitors produce:
lymphocytes, which include T cells, B cells, and natural killer (NK) cells.
red blood cells and all other immune cells, including phagocytes.
57
What is the role of dendritic cells in innate defense?
Dendritic cells find pathogens and engulf them within an endosome, then lysosome, then the epitope and MHC complex fold outwards.
Then dendritic cell travels to lymph node to activate helper T cell
58
What happens to the dendritic cell endosome after it engulfs a pathogen?
The endosome fuses with a lysosome, whose enzymes digest the pathogen, creating epitopes (fragments).
These fragments attach to MHC molecules and then this complex folds outward
59
What are the fragments called that result from the digestion of pathogens?
Epitopes.
60
What do dendritic cells do with the pathogen epitopes?
They attach the epitopes to presentation molecules (MHC-II) so they can present the complex to helper T cells
61
What is the structure of the complex formed by dendritic cells after attaching epitopes?
The complex (MHC and epitope) folds outward to sit on the outside of the dendritic cell membrane.
62
Where do dendritic cells travel after processing a pathogen?
They enter a lymphatic vessel and travel to a nearby lymph node.
63
What type of cell do dendritic cells encounter in the lymph node?
Helper T cell.
64
What part of the helper T cell recognizes the pathogen epitope in the dendritic cell?
What part recognizes the MHC-II?
The T cell receptor (TCR) of the helper T cell recognizes the pathogen epitope
CD4 glycoprotein associated with the TCR recognizes the MHC-II.
65
What glycoprotein associated with the TCR recognizes MHC-II?
CD4.
66
What is the result of the interaction between dendritic cells and helper T cells?
The dendritic cell stimulates activation of the helper T cell.
67
What is the role of the thymus in the adaptive immune system?
The thymus prevents adaptive immune cells from attacking the body's own cells.
## Footnote
This process is crucial in preventing autoimmune diseases.
68
What percentage of adaptive immune cells die in the thymus?
Around 98% of adaptive immune cells die in the thymus.
## Footnote
This phenomenon is referred to as 'Murder University'.
69
How does the human immune system generate antibodies despite having a limited number of genes?
The immune system generates billions of different antibodies through a process of mixing and matching genetic code.
## Footnote
This allows for diverse responses to various pathogens.
70
What is the function of B cells in the immune response?
B cells produce antibodies to fight off bacteria, viruses, and parasites.
## Footnote
They play a critical role in the adaptive immune system.
71
What enzyme do B cells use to shuffle DNA segments for antibody production?
B cells use an enzyme called RAG for shuffling DNA segments.
## Footnote
This process is essential for creating diverse antibody binding sites.
72
What are the three kinds of gene segments involved in antibody binding site creation?
V, D, and J segments.
## Footnote
These segments are critical for the process of VDJ recombination.
73
What is VDJ recombination?
VDJ recombination is the process where the RAG enzyme binds to V, D, and J segments for random selection and joining.
## Footnote
This process generates diversity in antibody binding sites.
74
What are the two types of chains that make up antibodies?
Light chains and heavy chains.
## Footnote
Both chains are proteins that combine to form a functional antibody.
75
How is antibody diversity further increased during the joining process of DNA segments?
Extra DNA is added or removed at the junctions of the segments.
## Footnote
This increases the antibody diversity from thousands to millions and eventually billions.
76
What are neutrophils responsible for in the immune system?
Neutrophils are white blood cells responsible for hunting and killing bacteria.
## Footnote
They are a crucial component of the innate immune response.
77
What triggers neutrophils to chase bacteria?
Bacteria release a chemoattractant detected by neutrophils.
## Footnote
This signaling leads to the polarization and movement of neutrophils toward the bacteria.
78
What is the process by which neutrophils engulf bacteria?
Phagocytosis.
## Footnote
This is the method by which neutrophils capture and destroy pathogens.
79
True or False: Neutrophils can immediately catch bacteria without any delay.
False.
## Footnote
Bacteria initially evade neutrophils due to their random movement.
80
What is a live attenuated vaccine?
A vaccine that introduces a weakened version of a living pathogen into the body, creating an immune response without causing disease.
81
What is a subunit (or recombinant) vaccine?
A vaccine that contains only part of the pathogen along with an adjuvant, making it safe for immunocompromised individuals but resulting in fewer memory cells.
82
What is the first step in developing a new vaccine?
Researchers need to identify the virus or bacterium causing the disease.
83
What must researchers do if the pathogen cannot be used?
Identify the pathogen's antigens.
84
How do viral vector vaccines work?
They inject incomplete genetic material from a pathogen inside a harmless virus, which then delivers the genetic material into the body.
85
What role do dendritic cells play in the immune response?
They present viral surface proteins to helper T cells.
86
What do cytotoxic T cells do?
They learn to destroy infected cells.
87
How does the helper T cell activate B cells?
1-The B cell has B cell receptors (BCRs) on its surface that bind a specific antigen floating around (like a piece of a virus or bacteria).
• The B cell internalizes the antigen and processes it into smaller pieces.
• These pieces are then displayed on its surface using MHC class II molecules.
2- Meanwhile, a helper T cell (CD4+) has already been activated by a professional antigen-presenting cell (like a dendritic cell).
• This T helper cell is now circulating, looking for its matching antigen.
• If it finds a B cell displaying its specific antigen on MHC class II, it binds to it using its T cell receptor (TCR).
3- “go signal” comes in two main forms:
1. Direct Contact (Signal 1)
• The B cell shows the antigen on its surface using MHC class II.
• The T helper cell recognizes this with its T-cell receptor (TCR).
• At the same time, a key interaction happens:
• B cell has: CD40
• T cell has: CD40L (CD40 Ligand)
• When these bind, it’s like flipping a switch: “Permission granted.”
⸻
2. Cytokine Signal (Signal 2)
• After the T helper cell binds, it releases cytokines. These cytokines tell the B cell:
• Multiply and make a clone army.
• Differentiate into plasma cells (which make antibodies) and memory B cells.
88
What is the first step in B cell development?
Stem cells in the bone marrow divide and rearrange their DNA to create unique B cell receptors (BCRs)
## Footnote
This process is crucial for generating diversity in the immune response.
89
What happens to self-reactive B cells?
They are eliminated to prevent autoimmunity
## Footnote
This elimination ensures that the immune system does not attack the body's own tissues.
90
What do remaining B cells do after self-reactive B cells are eliminated?
They wait for their specific antigen
## Footnote
Each B cell has a unique B cell receptor (BCR) that recognizes a specific antigen.
91
What occurs when a B cell finds the right antigen?
The B cell binds it, internalizes it, and presents a piece of it on an MHC class II molecule
## Footnote
This presentation is essential for T cell activation.
92
How does a helper T cell activate a B cell?
By binding to the MHC-II complex and activating the B cell through surface contact (CD40–CD40L) and cytokines
## Footnote
This interaction is critical for B cell proliferation and differentiation.
93
What are the two main outcomes of an activated B cell?
It clonally expands and forms:
* Plasma cells, which secrete antibodies
* Memory B cells, which remain in the body for faster responses in the future
## Footnote
Memory B cells are key for long-term immunity.
94
What is the role of B cell receptors (BCRs)?
Each BCR is designed to bind a specific epitope of an antigen
## Footnote
This specificity ensures that the immune response is tailored to particular pathogens.
95
What happens after a B cell binds to an antigen?
The B cell can be activated, especially with T cell help, and will secrete antibodies
## Footnote
The antibodies match the BCR and bind to the same epitope on pathogens.
96
How is the recognition of pathogens by B cells described?
Highly specific — like a lock and key
## Footnote
This specificity is crucial for effective immune responses.
97
What are the components of a B cell receptor (BCR)?
Each BCR has:
* Two heavy chains
* Two light chains
* Variable regions (V) at the tips
* Constant regions (C)
* Disulfide bridges
* Transmembrane region
## Footnote
The structure of BCRs allows for specific antigen binding.
98
What is humoral immunity?
Fights pathogens in body fluids (blood, lymph)
## Footnote
Involves B cells activating and producing antibodies.
99
What is the primary function of antibodies in humoral immunity?
Neutralize pathogens and help other cells destroy them
## Footnote
Antibodies play a key role in marking pathogens for destruction.
100
What is cell-mediated immunity?
Fights pathogens inside cells (like viruses or intracellular bacteria)
## Footnote
This aspect of immunity is primarily mediated by T cells.
101
What role do cytotoxic T cells (CD8+) play in cell-mediated immunity?
They kill infected cells directly
## Footnote
This direct action is crucial for controlling infections.
102
What is the role of helper T cells (CD4+) in the immune response?
Support both humoral and cell-mediated immunity, especially by helping B cells and activating other immune cells
## Footnote
Helper T cells are vital for coordinating the immune response.
103
What are the functions of antibodies?
1. Neutralization
Antibodies bind directly to pathogens or toxins and block their ability to enter or harm cells.
• Example: An antibody coats a virus so it can’t enter a host cell.
⸻
2. Opsonization
Antibodies coat a pathogen, making it easier for phagocytes (like macrophages and neutrophils) to recognize and eat it.
• Think of it as putting a “bite me” tag on the invader.
⸻
3. Activation of the Complement System
Certain antibodies (especially IgM and IgG) activate the complement cascade, which:
• Punches holes in pathogens (via the membrane attack complex)
• Promotes inflammation
• Helps more phagocytes arrive
⸻
4. Agglutination
Antibodies can bind multiple pathogens at once, clumping them together into a mass (agglutinate) that’s easier to remove.
• Especially helpful in clearing bacteria or viruses from fluids.
⸻
5. Precipitation
Antibodies can bind to soluble antigens (like toxins) and cause them to fall out of solution, making them easier to eliminate.
⸻
6. Antibody-dependent Cellular Cytotoxicity (ADCC)
Antibodies tag infected cells or cancer cells, and natural killer (NK) cells recognize the bound antibody and kill the cell.
⸻
7. Blocking adhesion
Antibodies prevent pathogens from attaching to host cells, which stops infection at the entry point.
⸻
104
What triggers inflammation during an infection?
When mast cells and macrophages encounter a pathogen or sense cell damage, they release cytokines and histamine, which trigger inflammation by increasing blood flow and attracting other immune cells to the site.
105
Compare and contrast antibody test and direct virus test
Antibody Test
• Detects: Antibodies made by your immune system in response to a virus
• When it’s positive: Usually means past infection (or vaccination)
• Timing: Takes days to weeks after infection to turn positive
• Use: To see if you’ve had the virus before
⸻
Direct Virus Test (e.g., PCR or antigen test)
• Detects: The virus itself (its genetic material or proteins)
• When it’s positive: Means current or very recent infection
• Timing: Positive early in infection, before antibodies form
• Use: To diagnose active infection
⸻
Summary:
• Antibody test = Did I have it before?
• Direct virus test = Do I have it now?
106
Compare and contrast (summary):
artificially acquired active immunity
artificially acquired passive immunity
naturally acquired active immunity
naturally acquired passive immunity
Summary:
• Active = your body makes the antibodies (and memory cells)
• Passive = you receive antibodies (no memory formed)
• Natural = happens through life events
• Artificial = happens through medical intervention
107
Naturally acquired active immunity
happens when you get infected with a pathogen. Your immune system responds by making its own antibodies and memory cells, giving you long-term protection.
108
Naturally acquired passive immunity
comes from your mother—either through the placenta before birth or through breast milk after birth. You receive ready-made antibodies, but your body doesn’t create memory cells, so protection is short-term.
109
Artificially acquired active immunity
comes from vaccines. You’re exposed to a harmless form of the pathogen (like weakened or inactivated parts), and your immune system builds its own antibodies and memory cells for long-term protection.
110
Artificially acquired passive immunity
involves receiving ready-made antibodies through a medical treatment (like an injection of antiserum or monoclonal antibodies). This provides quick but temporary protection, with no memory cell formation.
111
1. artificially acquired active immunity
2. artificially acquired passive immunity
3. naturally acquired active immunity
4. naturally acquired passive immunity
The type of protection provided by the injection of antirabies serum
The type of protection provided by the injection of diphtheria toxoid
A newborn's immunity to yellow fever.
The type of protection resulting from recovery from an infection.
Sure! Here are the correct matches:
• Artificially acquired passive immunity → The type of protection provided by the injection of antirabies serum
• Artificially acquired active immunity → The type of protection provided by the injection of diphtheria toxoid
• Naturally acquired passive immunity → A newborn’s immunity to yellow fever
• Naturally acquired active immunity → The type of protection resulting from recovery from an infection
112
The adaptive immune system has four major characteristics:
1. Immense diversity of lymphocytes and receptors
2. Self-tolerance: lack of reactivity against an animal's own molecules and cells
3. B and T cells proliferate after activation
4. Immunological memory
113
T cell receptors vs B cell receptors
Why B cell receptors (BCRs) are Y-shaped:
• BCRs are actually membrane-bound antibodies.
• They recognize and bind free-floating antigens (whole proteins, toxins, viruses).
• The Y-shape lets them grab antigens directly — each “arm” binds a specific part of the antigen (called an epitope).
• When activated, B cells can even secrete this receptor as an antibody.
Why T cell receptors (TCRs) are not Y-shaped:
• TCRs only recognize small fragments of antigens (epitopes) that are presented on MHC molecules by other cells.
• They don’t need to grab a big, whole antigen — just read a “displayed piece” like a scanner.
Analogy:
• BCRs = arms that catch floating objects (free antigens)
• TCRs = barcode scanners that read tagged items (MHC-presented fragments)
