π± MCAT Biology Review - 8 Flashcards
(153 cards)
1
Q
Which type of immunity is characterized by the absence of the thymus, as seen in DiGeorge syndrome?
A
Inability to mount specific defenses against viruses
The thymus is essential for T-cell development, crucial for adaptive immunity.
2
Q
Which cell type is NOT involved in cell-mediated immunity?
A
Plasma cells
Plasma cells are primarily involved in humoral immunity.
3
Q
What is a function of the lymphatic system?
A
Transports chylomicrons to the circulatory system
It plays a key role in fluid balance and immune responses.
4
Q
What type of cells are involved in antibody production?
A
Plasma cells, Memory cells, Helper T-cells
Cytotoxic cells are not directly involved in antibody production.
5
Q
Which statement about the innate immune system is NOT true?
A
Recognizes unique features of a pathogen
The innate immune system is nonspecific and does not target unique pathogen features.
6
Q
What is an example of adaptive immunity?
A
Memory B-cells generated through vaccination are activated when their antigen is encountered
It highlights the specific response and memory aspect of adaptive immunity.
7
Q
True or False: Active immunity is long-lived.
A
True
Active immunity develops over time and provides lasting protection.
8
Q
Where are most self-reactive T-cells eliminated?
A
Thymus
This is crucial for preventing autoimmune reactions.
9
Q
What is the immune response to downregulation of MHC molecules on somatic cells?
A
Natural killer cells induce apoptosis of affected cells
This mechanism helps eliminate cells that may be infected or dysfunctional.
10
Q
What occurs when CD8+ T-cells are activated?
A
Secretion of cytotoxic chemicals
CD8+ T-cells play a critical role in directly killing infected cells.
11
Q
Which cell type is NOT likely to cause a lymphoma?
A
Macrophages
Lymphomas arise from lymphoid lineage cells, not phagocytes like macrophages.
12
Q
The activation of T-cells with specific T-cell receptors is an example of:
A
Clonal selection
This process ensures that only T-cells specific to the antigen are activated.
13
Q
Which cell type is a phagocyte that attacks bacterial pathogens in the bloodstream?
A
Neutrophils
Neutrophils are key players in the innate immune response.
14
Q
What type of immunity is likely to be affected by the removal of the spleen?
A
Humoral immunity
The spleen is important for B-cell activation and antibody production.
15
Q
Which of the following is NOT an example of a nonspecific defense mechanism?
A
Cytotoxic T-cells destroy cells displaying foreign antigens
This is a specific adaptive immune response, not nonspecific.
16
Q
What are the two divisions of the immune system?
A
Innate immunity, Adaptive immunity
The innate system is always active, while the adaptive system is specific and slower to respond.
17
Q
What is the primary function of the bone marrow in the immune system?
A
Production of leukocytes
This is where all white blood cells are generated through hematopoiesis.
18
Q
What does the spleen do in the immune system?
A
Acts as a storage area for white blood cells and platelets, filters blood and lymph
It plays a crucial role in immune responses and recycling of red blood cells.
19
Q
What is the role of the thymus in the immune system?
A
Site of T-cell maturation
T-cells develop here before being released into the bloodstream.
20
Q
What tissues are referred to as gut-associated lymphoid tissue (GALT)?
A
Tonsils, Adenoids, Peyerβs patches, Lymphoid aggregates
These tissues are important for immune responses in the digestive system.
21
Q
What is the site of immune cell production?
A
Bone marrow
Bone marrow is responsible for the production of leukocytes through hematopoiesis.
22
Q
What is the site of T-cell maturation?
A
Thymus
23
Q
What are the functions of the spleen?
A
- Storage area for white blood cells and platelets
- Recycling center for red blood cells
- Filter of blood and lymph for the immune system
24
Q
What are the two groups of leukocytes?
A
- Granulocytes
- Agranulocytes
25
What do granulocytes contain that is effective against pathogens?
Granules with toxic enzymes and chemicals
26
What are the three types of granulocytes?
* Neutrophils
* Eosinophils
* Basophils
27
What are agranulocytes responsible for?
* Antibody production
* Immune system modulation
* Targeted killing of infected cells
28
What do monocytes become when they enter tissues?
Macrophages
29
What are some specific names for resident macrophages?
* Microglia (CNS)
* Langerhans cells (skin)
* Osteoclasts (bone)
30
What does CBC stand for in medical tests?
Complete blood count
31
What does a differential CBC count?
Each type of white blood cell
32
What does innate immunity refer to?
Nonspecific immune response
33
What does adaptive immunity involve?
Specific immune response developed through learning
34
What is humoral immunity driven by?
B-cells and antibodies
35
What is cell-mediated immunity driven by?
T-cells
36
What is the first line of defense in the immune system?
Skin (integument)
37
What role do defensins play in immunity?
Antibacterial enzymes found on the skin
38
What does the respiratory system use to prevent pathogens from entering?
Mucous membranes and cilia
39
What substance in the gastrointestinal tract helps eliminate pathogens?
Stomach acid
40
What is the role of the complement system?
Nonspecific defense against bacteria
41
How can the complement system be activated?
* Classical pathway (antibody binding)
* Alternative pathway (no antibodies required)
42
What do interferons do?
* Prevent viral replication
* Decrease permeability of infected cells
* Upregulate MHC class I and II molecules
43
What are the three main actions of activated macrophages?
* Phagocytize the invader
* Digest the invader
* Present antigens using MHC
44
What do MHC class I molecules do?
Present endogenous antigens on all nucleated cells
45
What is the difference between MHC class I and class II?
* MHC-I presents endogenous antigens
* MHC-II presents exogenous antigens
46
Which cells primarily display MHC class II molecules?
* Macrophages
* Dendritic cells
* Some B-cells
* Certain activated epithelial cells
47
What are pattern recognition receptors (PRR)?
Receptors that recognize categories of invaders
48
What is the role of Natural Killer (NK) cells?
* Detect downregulation of MHC
* Induce apoptosis in infected or cancerous cells
49
What are the types of granulocytes?
* Neutrophils
* Eosinophils
* Basophils
50
What is the lifespan of neutrophils?
A bit more than five days
51
What is chemotaxis?
Movement of an organism according to chemical stimuli
52
What is pus composed of?
Dead neutrophil collections
53
What is chemotaxis in relation to neutrophils?
The movement of neutrophils towards chemical stimuli, specifically products given off by bacteria.
54
What is opsonization?
The process of marking bacteria with antibodies from a B-cell for detection by neutrophils and other immune cells.
55
What role do eosinophils play in the immune system?
Eosinophils are primarily involved in allergic reactions and invasive parasitic infections.
56
What is the function of histamine released by eosinophils?
Histamine causes vasodilation and increased leakiness of blood vessels, allowing immune cells to move into tissues.
57
What is the primary function of basophils?
Basophils are involved in allergic responses and release histamine in response to allergens.
58
What is the difference between MHC-I and MHC-II?
MHC-I presents endogenous antigens to CD8+ T-cells, while MHC-II presents exogenous antigens to CD4+ T-cells.
59
What are the major classes of lymphocytes in the adaptive immune system?
B-cells and T-cells.
60
What is humoral immunity?
Immunity involving the production of antibodies by B-cells.
61
Where do B-cells mature?
In the bone marrow and spleen.
62
What is the primary response in the adaptive immune system?
The initial activation of B-cells and production of antibodies upon exposure to an antigen.
63
What are the two types of daughter cells produced by activated B-cells?
* Plasma cells
* Memory B-cells
64
What is the role of helper T-cells?
They coordinate the immune response by secreting lymphokines that recruit other immune cells.
65
What is the function of cytotoxic T-cells?
They directly kill virally infected cells by injecting toxic chemicals.
66
What is the significance of memory T-cells?
They provide a more rapid and robust response upon re-exposure to the same antigen.
67
What is the process of clonal selection in B-cells?
Only B-cells with high affinity for an antigen proliferate after exposure.
68
What are the five isotypes of antibodies?
* IgM
* IgD
* IgG
* IgE
* IgA
69
What is isotype switching in B-cells?
The process by which cells change the type of antibody they produce in response to specific cytokines.
70
What is the role of macrophages in bacterial infections?
They engulf bacteria, release inflammatory mediators, and present antigens on MHC-II.
71
What is the function of dendritic cells in the immune response?
They present antigens to T-cells and activate the adaptive immune response.
72
What happens during the secondary immune response?
Memory cells rapidly proliferate and differentiate into plasma cells to produce antibodies specific to the pathogen.
73
Fill in the blank: The adaptive immune system can be divided into _______ and cell-mediated immunity.
humoral
74
True or False: B-cells and T-cells are both created in the bone marrow but mature in different locations.
True
75
What is the function of suppressor T-cells?
They tone down the immune response and promote self-tolerance.
76
What do macrophages and other antigen-presenting cells do when they encounter bacteria?
Engulf bacteria, release inflammatory mediators, digest bacteria, present antigens with MHC-II
## Footnote
MHC-II is a class of molecules found on professional antigen-presenting cells that present antigens to CD4+ T-cells.
77
What role do cytokines play in the immune response?
Attract inflammatory cells, including neutrophils and additional macrophages
78
What happens to mast cells during inflammation?
They degranulate, releasing histamine and increasing capillary leakiness
79
What is the function of dendritic cells in the immune response?
Present antigens to B-cells and T-cells in the lymph nodes
80
What are the two types of CD4+ T-cells?
Th1 and Th2
81
What cytokine do Th1 cells release?
Interferon gamma (IFN-Ξ³)
82
What do Th2 cells assist with in the immune response?
Activate B-cells and are more common in parasitic infections
83
What happens to plasma cells after the pathogen is eliminated?
They die, but memory B-cells and T-cells remain
84
What is the role of memory cells in the immune system?
Allow for a faster secondary response upon later exposure to the pathogen
85
What do virally infected cells produce to combat infection?
Interferons
86
What do CD8+ T-cells do in response to virally infected cells?
Recognize MHC-I and antigen complex, inject toxins to promote apoptosis
87
What is the consequence of a virus downregulating MHC-I production?
Natural killer cells induce apoptosis of infected cells due to absence of MHC-I
88
What are self-antigens?
Proteins and carbohydrates on the surface of every cell in the body
89
What condition arises when the immune system attacks self-antigens?
Autoimmunity
90
What is an example of an autoimmune disease?
Type I diabetes mellitus
91
What process eliminates T-cells that respond to self-antigens?
Negative selection in the thymus
92
What is active immunity?
Immune system is stimulated to produce antibodies against a specific pathogen
93
How can active immunity be achieved?
Natural exposure or artificial exposure (vaccination)
94
What is passive immunity?
Transfer of antibodies to an individual, providing temporary immunity
95
What is a natural example of passive immunity?
Transfer of antibodies across the placenta or through breast milk
96
What was the claim made by a 1998 paper regarding vaccines?
A link between vaccines and autism
97
What is the impact of the 1998 study on public perception of vaccines?
Influenced some parents to avoid immunizing their children
98
What is the main function of plasma cells?
Produce antibodies
99
What do memory B-cells do?
Provide a rapid response upon re-exposure to a pathogen
100
What is the difference between active and passive immunity?
Active immunity involves the individual's immune response; passive immunity is the transfer of antibodies
101
What is the consequence of a blockage of flow from a lymph node?
Impairment of the lymphatic system and potential impact on immune response
102
What is the role of the lymphatic system in relation to B-cells?
B-cells proliferate and develop within the lymphatic system, especially in lymph nodes
103
What is the significance of Fas Ligand (FasL) and Tumor Necrosis Factor (TNF) in immune-mediated liver damage?
Their inhibition did not prevent liver damage in the study
104
How was the role of perforin-1 tested in the study?
By injecting T-cells with and without perforin-1 and measuring liver damage
105
What indicated that perforin-1 contributes to liver damage?
Significant difference in liver damage between control and perforin-1 knockout cells
106
What is the primary function of the lymphatic system?
Provides a secondary system for circulation and serves multiple purposes for the body.
107
How do lymphatic vessels connect to the cardiovascular system?
Via the thoracic duct in the posterior chest.
108
What fluid do lymphatic vessels carry?
Lymphatic fluid (lymph).
109
What are lymph nodes?
Small, bean-shaped structures along the lymphatic vessels that provide a space for immune system cells to interact with pathogens.
110
What is chyle?
Lymphatic fluid carrying chylomicrons, which takes on a milky white appearance.
111
What is the role of lacteals?
Transport fats from the digestive system into the bloodstream.
112
What are the two main types of immunity in the immune system?
* Innate immunity * Adaptive immunity
113
What is innate immunity?
Defenses that are always active but cannot target specific invaders or maintain immunologic memory.
114
What is adaptive immunity?
Defenses that take time to activate, target specific invaders, and maintain immunologic memory.
115
What is the primary site of T-cell maturation?
Thymus.
116
Where do immune cells originate?
Bone marrow.
117
What role do macrophages play in the immune system?
Ingest pathogens and present them on MHC molecules.
118
What is the function of natural killer cells?
Attack cells not presenting MHC molecules, including virally infected cells and cancer cells.
119
What is the difference between MHC class I and MHC class II?
MHC class I presents endogenous antigens to cytotoxic T-cells; MHC class II presents exogenous antigens to helper T-cells.
120
What is the function of B-cells?
Produce antibodies and participate in humoral immunity.
121
What do antibodies do?
* Opsonize pathogens * Cause agglutination * Neutralize pathogens
122
What are memory B-cells?
B-cells that lie in wait for a second exposure to a pathogen to mount a rapid immune response.
123
What is the role of helper T-cells?
Coordinate the immune response and activate various arms of immune defense.
124
What is the purpose of immunization?
To induce active immunity prior to exposure to a particular pathogen.
125
What is passive immunity?
The transfer of antibodies to an individual.
126
What is edema?
Swelling due to fluid collecting in tissue when lymphatic channels are overwhelmed.
127
True or False: The spleen is involved in the activation of B-cells.
True.
128
Fill in the blank: The lymphatic system serves to _______ fluid distribution.
Equalize.
129
What are the main components of the innate immune system?
* Skin * Mucus * Tears and saliva * Stomach acid * Complement system
130
What are granulocytes?
* Neutrophils * Eosinophils * Basophils
131
What happens during positive selection of T-cells?
T-cells that can react to antigen presented on MHC are allowed to survive.
132
What is the consequence of negative selection in T-cells?
Self-reactive T-cells undergo apoptosis before leaving the thymus.
133
What is the primary role of the thymosin hormone?
Promotes T-cell development.
134
What is the relationship between lymphatic and cardiovascular systems?
The lymphatic system aids in returning excess fluid to the bloodstream and connects through the thoracic duct.
135
What process do B-cells undergo in response to an antigen to increase specificity?
Hypermutation of their antigen-binding sites
## Footnote
This process allows only B-cells with the highest affinity for the antigen to survive and proliferate.
136
What is positive selection in T-cells?
Survival of T-cells that can respond to antigen presented on MHC
## Footnote
T-cells that do not respond undergo apoptosis.
137
What happens during negative selection of T-cells?
T-cells that respond to self-antigens undergo apoptosis
## Footnote
This occurs before they leave the thymus.
138
What is the role of memory cells in the immune system?
Allow for a rapid and robust secondary response
## Footnote
Memory cells help the immune system respond more effectively upon re-exposure to an antigen.
139
Define active immunity.
Stimulation of the immune system to produce antibodies against a pathogen
## Footnote
This occurs through exposure to the pathogen or via vaccination.
140
Define passive immunity.
Transfer of antibodies to prevent infection without stimulating plasma cells
## Footnote
An example includes antibodies transferred from mother to fetus.
141
What is the consequence of an infection that prevents fluid return from the lower leg?
Edema and elephantiasis
## Footnote
Elephantiasis is characterized by severe swelling and skin thickening.
142
What does the thoracic duct do?
Carries lymphatic fluid into the left subclavian vein
143
What type of pathogens are T-lymphocytes specific against?
Intracellular pathogens
## Footnote
This includes viruses and some intracellular bacteria.
144
List the four types of T-cells involved in cell-mediated immunity.
* Cytotoxic T-cells
* Helper T-cells
* Memory T-cells
* Suppressor T-cells
145
What is the main function of the lymphatic system?
Collect excess interstitial fluid and return it to the circulatory system
## Footnote
It also absorbs chylomicrons and aids in immune functions.
146
What are plasma cells?
Differentiated immunoglobulin-secreting B-lymphocytes
## Footnote
They are involved in humoral immunity.
147
True or False: The innate immune system recognizes specific antigens.
False
## Footnote
The innate immune system does not identify specific pathogens.
148
What is clonal selection in the adaptive immune system?
Activation of cells with antibodies or T-cell receptors specific to the antigen
## Footnote
This process ensures a targeted immune response.
149
What are the only phagocytes that attack bacteria?
* Neutrophils
* Dendritic cells
150
What effect does spleen removal have on immunity?
Reduction of humoral immunity
## Footnote
The spleen is a site for B-cell maturation and proliferation.
151
What is a non-specific defense mechanism against foreign invasion?
Skin and mucous membranes
## Footnote
These provide a physical barrier and include other mechanisms like macrophage activity.
152
What is the role of natural killer cells?
Monitor MHC class I expression and induce apoptosis in affected cells
## Footnote
They target cells with reduced MHC expression due to viral infection or cancer.
153
What is isotype switching?
Changes in the isotype of antibody produced
## Footnote
This process is not caused by cytotoxic T-cells.
