Immunity & Host Defense Flashcards
1
Q
What is immunity?
A
The body’s ability to resist disease
2
Q
What are the 2 types of immunity?
A
Innate & adaptive
3
Q
What does innate immunity do?
A
Protect humans from most infectious disease
4
Q
What are 4 characteristics of innate immunity?
A
- Exists at birth and always present
- No memory
- Can be tissue specific
- Chemical & physical barriers
5
Q
What is natural host resistance susceptible to?
A
Pathogens, but this susceptibility varies from species to species
6
Q
What does tissue specificity mean?
A
Pathogens prefer a specific body site to initiate infection
7
Q
What are the physical and chemical barriers to infection on the skin?
A
- Prevents invasion of microbes through tight junctions
- Keratin is a protective protein
- Slightly acidic (about pH 5)
- High [NaCl] for periodic drying
8
Q
What are the physical and chemical barriers to infection of mucous membranes?
A
- Mucous traps microbes
- Contains antimicrobial secretions
9
Q
What are some examples of antimicrobial secretions from mucous glands and what do they do?
A
- Lysozyme cuts beta-1,4 glycosidic linkages in peptidoglycan
- Defensins – antimicrobial peptides that poke holes in bacterial cell membranes
10
Q
What are the physical and chemical barriers to infection of the respiratory tract?
A
- Ciliated cells line the mucuous membranes of airways
- Sweeping action moves mucous and microbes away from the lungs
11
Q
What are the physical and chemical barriers to infection in the stomach?
A
- Strong acidity (about pH 2)
- Proteolytic enzymes
- Mucous membranes lining stomach destory most microbes
12
Q
What are the physical and chemical barriers to infection of the small intestine?
A
- Rapid change in pH
- Pancreatic enzymes
- Bile
13
Q
What are the physical and chemical barriers to infection of the large intestine?
A
- Normal microbiota that already reside in and on body
- Take up attachment sites
- Limit available nutrients
- Make antimicrobial compounds
14
Q
What are the physical and chemical barriers to infection of the genitourinary tract?
A
- Urine – metabolic waste products that are toxic to many microbes
- Flushing action
- Normal microbiota
15
Q
What does Lactobacillus acidophilus do?
A
Ferments glucose to lactic acid
16
Q
What is the lymphatic system?
A
A collection of tissues that bring specialized cells (lymphocytes) into contact with foreign material (antigen)
17
Q
What is the lymphatic system made of?
A
- Lymph vessels that carry lymph
- Lymphoid organs
18
Q
What are primary lymphoid organs and what do they do?
A
- Bone marrow and thymus
- Produce and mature leukocytes
19
Q
What are secondary lymphoid organs and what do they do?
A
- Lymph nodes, spleen, and mucosa associated lymphoid tissue (MALT)
- Contain leukocytes arranged to filter out microbes and antigens
20
Q
What is mucosa associated lymphoid tissue (MALT)?
A
Leukocytes constantly sample their surroundings by phagocytosis looking for foreign material
21
Q
What are leukocytes?
A
Cells that circulate in the blood and lymph, and reside in lymphoid organs
22
Q
What branch of immune response are leukocytes involved in?
A
Both
23
Q
What are the 3 types of leukocytes?
A
1) Granulocytes
2) Monocytes
3) Lymphocytes
24
Q
What are the 3 types of granulocytes?
A
1) Basophils & mast cells
2) Eosinophils
3) Neutrophils
25
What are distinguishing characteristics of granulocytes?
- Cytoplasm contains granules filled with reactive chemicals
- Can kill microbes
- Signal other components of immunity
26
What are 4 characteristics of basophils & mast cells?
- Non-phagocytic
- Circulate in blood (basophils) or reside in mucosal tissue (mast cells)
- Can be triggered to degranulate
- Release vasoactive mediators that trigger inflammation
27
What do basophils & mast cells stain with?
Basic dyes
28
What do eosinophils stain with?
Acidic dyes
29
What are characteristics of eosinophils?
- Non-phagocytic
- Can leave blood and enter tissues in areas of inflammation
- Attack large parasites
- Release radioactive oxygen intermediates
30
What are characteristics of neutrophils?
- Granules filled with digestive enzymes (lysozyme, defensins)
- Circulate in blood and migrate to infection site
- Highly phagocytic
- Central component of innate immunity
31
What are 2 types of monocytes?
1) Macrophages
| 2) Dendritic cells
32
What are monocytes?
- Circulate in blood then migrate into tissues and differentiate into macrophages and dendritic cells
- Strongly phagocytic cells involved in antigen presentation
33
Where do macrophages reside?
Tissues -- lungs, liver, spleen, connective tissues
34
What are toll-like receptors and what do they do?
- Specific surface molecules the recognize pathogens
| - Induce phagocytosis
35
What type of leukocyte are toll-like receptors found on?
Macrophages
36
Where do dendritic cells reside?
Reside in tissues by migrate to lymphoid organs
37
What do dendritic cells do?
- Constantly sample surroundings by phagocytosis
| - Once in lymphoid organs, present foreign antigens on their surface to B & T lymphocytes
38
What are lymphocytes?
Specialized leukocytes involved primarily in adaptive immune response
39
What are the 3 types of lymphocytes?
1) B lymphocytes
2) T lymphocytes
3) Natural killer cells (NK cells)
40
What are B cells?
- Antibody producing cells
| - Involved in humoral immune response
41
What are T cells involved with?
Cell mediated immune response
42
What do NK cells do?
Destroy abnormal body cells, such as cancer cells & cells infected by bacteria & viruses
43
What is innate immunity?
Ability to destroy a pathogen that has never been encountered before
44
What is involved in innate immunity?
Phagocytic leukocytes (neutrophils & macrophages) that recognize pathogen-associated molecular patterns
45
What happens in oxygen-independent phagocytosis?
- Phagocytes engulf and destory invading microbes
- Cell membrane invaginates around a foreign particle
- Engulfs it into a phagosome
46
What 2 cells form a phagolysosome?
Phagosome & lysosome
47
What is a phagolysosome filled with?
- Lysozyme & defensins
- Proteases
- Lipases
- Nuclease
48
What happens in oxygen-dependent phagocytosis before invaders have been killed?
- Activated phagocytes produce reactive oxygen compounds (H2O2, O2-, HOCl, NO)
- Kill ingested microbes by oxidizing cell components
49
What happens in oxygen-dependent phagocytosis after invaders have been killed?
- Neutrophils perform exocytosis & fragments expelled from cell
- Macrophages & dendritic cells become antigen presenting cells -- fragments of the intruder are presented on the cell surface to trigger an adaptive immune response
50
What is inflammation?
General, non-specific reaction to pathogens, toxins, or tissue damage
51
What are the 5 cardinal signs of inflammation?
- Redness
- Warmth
- Pain
- Swelling
- Loss of function
52
What do tissue and leukocytes produce in response to infection?
Proinflammatory cytokines
53
What are the consequences of releasing proinflammatory cytokines and what do they do?
- Blood vessel dilation to bring more leukocytes to area
- Vessel walls become more permeable so leukocytes can squeeze through and attack invading pathogens
- Temperature increase to slow growth of pathogens
- Blood leaking into tissue spaces to clot and prevent movement of pathogens
54
When is adaptive immunity acquired?
After a pathogen has been encountered for the first time
55
What are the 2 branches of adaptive immunity?
- Humoral (antibody mediated)
| - Cellular (cell mediated)
56
What is another name for antibodies?
Immunoglobulins
57
What is found in each antibody?
- 2 identical antigen binding sites (Fab)
| - One Fc site that can interact with other components of the immune system
58
What are the 5 classes of antibodies?
1) IgG
2) IgM
3) IgA
4) IgD
5) IgE
59
What are characteristics of IgG?
- Monomer
- Most abundant antibody in blood and tissues
- Most important for combating a pathogen
60
Which antibody is most abundant in blood and tissues?
IgG
61
Which antibody is most important for combating a pathogen?
IgG
62
What are characteristics of IgM?
- Pentamer
- First antibody made when new antigen is encountered
- Excellent at agglutination
- Does not leave blood nor enters tissues
63
Which antibody is made first when a new antigen is encountered?
IgM
64
What are characteristics of IgA?
- Dimer
- Secreted into saliva, tears, & mucous
- Helps to protect mucosal surfaces
65
What are characteristics of IgD?
- Monomer
- Found on the surface of B cells
- Plays a role in activating B cells to respond against an antigen
66
Which antibody helps activate B cells?
IgD
67
What are characteristics of IgE?
- Monomer
- Found on the surface of mast cells & basophils
- Trigger release of histamine, which causes an allergic reaction
68
Which antibody plays a role in triggering an allergic reaction?
IgE
69
What are the 5 major functions of antibodies?
1) Neutralization
2) Opsonization
3) Agglutination
4) Antibody mediated cytotoxicity
5) Complement activation
70
How do antibodies accomplish neutralization?
- Ab stick to antigens on a foreign particle and block attachment site
- Stops bacteria, viruses and toxins from entering host cells
71
How do antibodies accomplish opsonization?
- Antibodies stick to a pathogen's surface and flag down phagocytes
- Phagocyte interacts with Fc region and engulfs pathogen
- Greatly increases rate of phagocytosis
72
How do antibodies accomplish agglutination?
- Ab can stick to 2 identical antigens
- Bridges particles together in clumps
- Can be phagocytized more easily
73
How do antibodies accomplish antibody mediated cytotoxicity?
- Ab binds to antigen on the surface of a parasite
- Fc can interact with eosinophils
- Eosinophils release enzymes & reactive oxygen intermediates to attack parasite
74
How do antibodies accomplish complement activation?
- Ab bound to a bacterial cell can activate complement
- Results in membrane attack complex (MAC)
- Insert into bacterial membranes
- Forms a pore, and cell leaks and dies
75
What are 4 properties of adaptive response?
1) Acquired -- pathogen must be encountered before adaptive immune response is mounted
2) Specific -- can mount a direct attack against a specific pathogen
3) Memory -- once a specific pathogen has been encountered immune system cells multiply and produce long living memory cells
4) Tolerance -- inability to mount against self-antigens
76
How does the body prevent immune system cells from recognizing self-antigens?
Those cells that recognize self-antigens are destroyed during development
77
What is a primary response?
The first time a new pathogen is encountered, the adaptive immune response is weak
78
What is the result of a primary response?
Immunologic memory
79
What is a secondary response?
The second time a pathogen is encountered memory cells respond quickly
80
What is an immunogen?
Any foreign particle that can induce an adaptive immune response
81
What is the size of immunogens?
Relatively large
82
What are antigens?
Any substance that can react with antibodies or receptors on adaptive immune system cells
83
What are antibodies?
Globular proteins made by the immune system that can bind to and inactivate foreign antigens
84
What are epitopes?
The actual part of an antigen that can bind to an antibody
85
What happens as an antigen has more epitopes?
It becomes more immunogenic, and a more diverse population of antibodies can be generated against it
86
What is a hapten?
Low molecular weight compound too small to be immunogenic on its own, but can be highly antigenic
87
What is an example of a hapten and what does it do?
- Penicillin
- Can bind to proteins in the blood forming a strong immunogen
- Antibodies are formed against it, leading to an allergic response
88
What branch of the immune response are B lymphocytes involved in?
Humoral
89
What are B lymphocytes?
Antibody producing cells
90
What are Tc cells?
- T-cytotoxic cells
| - Destroy abnormal body cells
91
What branch of the immune response are Tc cells involved in?
Cell mediated
92
What are Th cells?
- T-helper cells
| - Help B & Tc cells prepare for an immune response
93
What branch(es) of the immune response are Th cells involved in?
Humoral & cell-mediated
