Immunity I Flashcards
1
Q
what is immunity
A
protection against infections
2
Q
what is the immune system
A
collection of cells and molecules that are responsible for defending the body against pathogens
3
Q
what is a pathogen
A
organism that causes disease
4
Q
what is the goal of the immune system
A
- prevent foreign substances from entering the body
- establish immunocompetence ability of the body to produce a robust immune response following exposure to disease producing agents
5
Q
what does innate immunity do
A
- mediates initial protection against infections
- nonspecific defense
- rapidly eliminate microbes that enter host tissues
- eliminate damaged and necrotic cells
6
Q
what are the nonspecific defenses of the innate immune system
A
- physical barriers: skin, mucus membrane, nasal hairs, respiratory tract cilia
- chemical barriers: skin pH, mucous secretions, gastric acids, tears, sweat, saliva
- effector cells: macrophages, neutrophils, NK cells
7
Q
what do PAMPs do
A
recognize general microbial patterns through pattern recognition receptors
8
Q
what do DAMPS do
A
recognize molecules released from damaged or necrotic host cells
9
Q
what do neutrophils do
A
- first cell type to respond to most infections: bacterial and fungal
- short- lived
- ingest and degrade dead cells, debris, tumor cells, pathogens, foreign material through phagocytosis
- may be activated by macrophages
10
Q
what do dendritic cells do
A
- thin, membranous cytoplasmic processes
- present antigens to T cells
- abundant near epithelium, mucus membranes
- help shape adaptive immune response
11
Q
what do macrophages do
A
- survive in extravascular tissue for long periods
- ingest and degrade dead cells, debris, tumor cells, pathogens, foreign material through phagocytosis
- may present antigens to T cells
- release cytokines to activate other immune cells
12
Q
describe natural killer cells and what they dp
A
-capable of rapidly attacking and killing infected cells
- induce cell apoptosis
- release cytokines to activate other immune cells
13
Q
what is the complement system
A
collection of circulating and membrane associated proteins important in the defense against microbes
14
Q
what is the classical pathway
A
activated by antibodies that bind to microbes or other antigens -> component of adaptive immunity - humoral
15
Q
what is the alternate pathway
A
activated when complement proteins are activated on microbial surfaces -> component of innate immunity
16
Q
what is the lectin pathway
A
activated by mannose binding lectin binds to surface glycoproteins on microbes -> component of innate immunity
17
Q
describe opsonization and phagocytosis
A
C3b coats microbes, promotes binding to phagocytes -> microbes ingested and destroyed
18
Q
describe inflammation in the complement system
A
C5a and C3b are chemoattractants for leukocytes -> recruit and promote inflammation
19
Q
describe cell lysis in complement system
A
complement activation concludes with the MAC -> microbial death
20
Q
what are cytokines
A
soluble proteins that mediate immune and inflammatory reactions
21
Q
what do cytokines do
A
- responsible for communication b/w leukocytes and other cells
- most cytokines function in autocrine and paracrine actions
22
Q
when are cytokines secreted
A
in response to external stimuli
23
Q
what immune response is elicited by extracellular bacteria
A
acute inflammatory response and complement
24
Q
what are intracellular bacteria eliminated by
A
phagocytes
25
what immune response is elicited by viruses
type I interferon, NK cells
26
what are toll like receptors and what do they do
- plasma membrane and endosomal receptors
- recognize LPS, viral and bacterial RNA/DNA
27
what are NOD like receptors and what do they do
- cytosolic receptors
- recognize necrotic cell products, ion disturbances, microbial products
28
what are the C- type lectin receptors and what do they do
- plasma membrane
- recognize fungal polysaccharides
29
what are the primary lymphoid organs
bone marrow and thymus
30
where do B cells develop
bone marrow
31
where do T cells develop
thymus
32
what happens in secondary lymphoid organs
-sites where adaptive immunity is initiated
- lymphocytes have contact with antigens
33
what does bone marrow do
= produces the cells of the immune system from stem cell precursors
34
describe the bone marrow
soft, spongy tissue in the medullary cavity of bones
35
describe what happens int the thymus
-lymphatic organ responsible for the matruation and specializiation of white blood cells called T lymphocytes
- after maturation, T lymphocytes enter bloodstream and travel to secondary lymphatic sites
- involutes with age
36
what is in waldeyers ring
- pharyngeal tonsils
- tubal tonsil
- palatine tonsil
- lingual tonsil
37
what is the first line of defense
innate immunity
38
describe innate immunity
-develops quickly
- rapidly reacts against infectious pathogens
- no memory
39
describe adaptive immunity
- specialized immunity
- develops more slowly
- mediates an effective defense against infections
- memory for future encounters
40
what does adaptive immunity recognize
diverse foreign substancesh
41
when is adpative immunity triggered
when microbes pass through epithelial barriers, recognized by lymphocytes in lymphoid organs
42
what is an antigen
substance that can induce an immune response
43
what is humoral immunity
mediated antibodies produced by B lymphocytes
44
what is cell mediated immunity
mediated by T lymphocytes
45
what produces antibodies
B cells
46
what do antibodies do
- neutralize and eliminate microbes and microbial toxins
- prevent infections from being established
- secreted into circulation and mucosal fluids
47
what makes up 10-20% of circulating peripheral lymphocyte population
B lymphocytes
48
what do B lymphocytes recognize
-antigens through membrane bound IgM
- chemical structures: soluble or cell associated proteins, lipids, polysaccharides, nucleic acids, small chemicals
49
what do B lymphocytes differentiate into
plasma cells after stimulation
50
what are the 5 classes of antibodies
IgG, IgM, IgA, IgE, IgD
51
describe IgG and what it does
- most abundant antibody
- found in blood and serum
- efficiently opsonizes pathogens
- can cross placenta
52
what are the four subclasses of IgG
IgGI, IgG2, IgG3, IgG4
53
describe IgA and what it does
- most commonly observed in mucous membrane secretions
- forms dimer when secreted
- neutralizing AB
54
describe IgM and what it does
- largest antibody
- first antibody produced in response to antigen
- most efficient antibody to activate complement
55
describe IgE and what it does
-functions against helminth infections
- mediated allergic reactions (hypersensitivity type I)
- least common antibody
56
describe IgD and what it does
- function unknown
- may play role in B cell activation
- not secreted
57
when does rearrangement and assembly of gene segments in antibodies occur
during B cell development
58
describe antibody switching
- IgM and IgD are present as membrane bound antibodies
- B cells may produce AB of other classes
59
when does antibody class switching occur
after stimulated by antigen and CD4 T helper cells
60
in antibody class switching the B cell still maintains its antigen specificity though _______ switched
heavy chain
61
what does antibody class switching do
broadens the functional capabilities of humoral immunity
62
second exposure to antigen activates ______
memory B cells
63
what are memory B cells
generated after primary response to respond to antigen in future
64
how long to memory B cells circulate for
years after infection
65
describe memory B cells
-a fraction of activated B cells become memory cells
-circulate in the blood lymphoid organs
- do not actively secrete antibodies
- rapidly differentiate into antibody producing cells upon re exposure
66
what is the goal of vaccination
- to stimulate protective adaptive immune responses against microbes
- introduce non pathogenic forms of microbesw
67
what are some types of vaccines
inactivated vaccines
- live-attenuated vaccines
- mRNA vaccine
68
what is active immunity
- antibodies are produced by the body in response to an antigen
69
what is natural active immmunity
individual with infectious disease
70
what is artificial active immunity
vaccination- attenuated virus or bacteria
71
what immunity does active immunity provide
long term immunity through memory cells
72
what is passive immunity
antibodies derived from another source
73
what is an example of passive immunity
- maternal antibodies transferred across placenta to fetus
74
what type of immunity does passive immunity provide
- short term but no memory cells produced
75
what does cell mediated immunity do and what is it mediated by
- combats infections by intracellular microbes
- mediated by T lymphocytes
76
what are the types of intracellular pathoens
- microbes ingested by phagocytes - some may resist microbicidal activity
- viruses- able to infect and replicate in cytoplasm of host cells
77
describe cell mediated sequence
-APCs travel to lymphoid tissues and present antigen via MHC
- T cels are activated, proliferate and differentiate into effector and memory cells
- T cells migrate to site of infection and initiate response with CD4 or CD8
- some actviated T cells remain in lymph tissues - B cells producing ABs or become memory T cells
78
where are MHC genes locatde
polymorphic genes on chromosome 6
79
what is the antigen for MHC
human leukocyte antigen (HLA)
80
what do MHCs do
- display peptide antigens for recognition by T lymphocytes
-help cells recognize between self and non self
81
where are MHC class I cells found and what are they recognized by
found on all nucleated cells
-recognized by CD8 T cells
82
where are MHC Class II cells found and what are they recognized by
found on APC surfaces and recognized by CD4 T cellsw
83
what are the APC cells
macrophages, dendritic cells, B cells
84
describe CD4 helper T cells
- become effector cells in response to antigen
- APC presents antigen via MHC II
- will release cytokines to activate other cells
- clonal expansion of CD4 T cells
85
what do CD8 T cells do
- become effector cells in response to antigen
- APC presents antigen on MHC I
- will release enzymes to kill infected cells
86
where are memory cells found
lymphoid organs, mucosal tissue and circulation
87
what are central memory cells
rapid clonal expansion after re exposure
88
describe the decline of the immune response
- immune responses are self limited
- effector lymphocytes die by apoptosis after microbe is eliminated
- allows system to return to resting state
89
