ch. 43 part 1 Flashcards
1
Q
pathogen
A
any agent that causes disease and infects a wide range of animals (including humans)
2
Q
ex. of pathogens
A
- parasites
- protozoa
- fungi
- prokaryotes
- viruses
- prions
3
Q
2 types of molecular recognition for detection of non-self molecules, particles, and cells
A
- innate immunity
- adaptive immunity
4
Q
where is innate immunity found
A
in all animals and plants
5
Q
innate immunity in vertebrates
A
- first response to infection
- foundation adaptive immunity
6
Q
ex. of innate immunity in insects
A
- exoskeleton made of chitin forms first barrier to pathogens
- digestive system protected by chitin-based barrier and lysozyme (breaks down bacterial cel walls)
- hemocytes circulate within hemolymph and carry out phagocytosis
- immune system recognizes bacteria/fungi by structures on cell walls
- defense against viruses based on recognition of double-stranded RNA
7
Q
hemocyte function in insects
A
- secrete antimicrobial peptides that disrupt the plasma membranes of fungi/bacteria
- carry out phagocytosis in hemolymph
8
Q
what are the innate defenses of mammals similar to?
A
those of invertebrates
9
Q
innate defenses of mammals/invertebrates
A
barrier defenses, phagocytosis, antimicrobial peptides
10
Q
innate defenses unique to vertebrates
A
- natural killer cells
- interferons
- inflammatory response
11
Q
innate immunity definition
A
general recognition that something is foreign
12
Q
barrier defense examples
A
- skin and mucous membranes of respiratory, urinary, reproductive tracts
- lysozymes that break cell walls in tears, saliva, and mucous of eyes/upper respiratory tract
13
Q
what does mucus do
A
trap and allow for removal of microbes
14
Q
what body fluids are hostile to microbes?
A
saliva, mucus, tears
15
Q
what do the low pH of skin and digestive system do
A
prevent growth of many bacteria
16
Q
cellular innate defenses (mammals)
A
- detect, devour, destroy pathogens
17
Q
how do mammal cells recognize groups of pathogens
A
TLRs
18
Q
TLRs - toll-like receptors
A
recognize fragments of molecules characteristic of a set of pathogens
19
Q
2 main types of phagocytic cells in mammals
A
- neutrophils
- macrophages
20
Q
neutrophils
A
phagocytic cells that circulates in blood and destroy infected cells
21
Q
macrophages
A
phagocytic cells that migrate through the body or reside permanently in organs/tissues
22
Q
2 additional types of phagocytic cells
A
- dendritic cells
- eosinophils
23
Q
dendritic cells
A
stimulate development of adaptive immunity
- populate tissues that come in contact with the environment
- migrate to lymph nodes after detecting pathogens
24
Q
eosinophils
A
discharge destructive enzymes against parasites - multicellular invaders
25
natural killer cells
tumors, cancers
- circulate through body and detect abnormal cells
- release chemicals leading to cell death, inhibiting spread of virally infected/cancerous cells
26
what system do many cellular innate defenses involve
lymphatic system
27
how do peptides and proteins function in innate defense
by attacking pathogens or impeding their reproduction
28
interferon proteins
innate defense by interfering with viruses and helping activate macrophages
- limit cell-cell spread of viruses
- infected cells release interferons which signal other cells
29
complement system
causes lysis of invading cells and helps trigger inflammation
30
how many proteins make up complement system
30
31
complement protein process
- circulate in an inactive state
- activated by coming in contact with a pathogen
- activation leads to pathogenic cell exploding
32
inflammatory response
pain and swelling brought about by molecules released upon injury or infection
33
mast cells
immune cells found in connective tissue
34
what do mast cells release
histamine
35
histamine function
triggers blood vessels to dilate and become more permeable
36
activated complement proteins
- promote further release of histamine
- attract more phagocytic cells
37
what does enhanced blood flow to a site do
helps deliver antimicrobial peptides
38
pus
fluid rich in white blood cells, dead pathogens, and cell debris from damaged tissues
39
what type of inflammation is a fever
systemic - triggered by substances released by macrophages in response to certain pathogens
40
types of inflammation
local or systemic
41
septic shock
life-threatening condition caused by an overwhelming inflammatory response
42
how do some pathogens avoid destruction
- modifying their surface to prevent recognition
- resisting breakdown following phagocytosis
43
streptococcus pneumoniae
major cause of pneumonia and meningitis in humans
44
tuberculosis (TB)
disease that kills more than 1 million people a year
45
what does adaptive immunity rely on
2 types of lymphocytes (white blood cells):
1. T cells
2. B cells
46
lymphocytes that mature in the thymus
T cells
47
lymphocytes that mature in the bone marrow
B cells
48
antigens
substances that can elicit a response from a B or T cell
49
how to T/B cells bind to antigens
via antigen receptors
- specific to part of one molecule of that pathogen
50
epitope
small, accessible part of an antigen that binds to an antigen receptor
51
what is each individual B/T cell specialized to recognize?
epitope on a specific antigen
52
B cell antigen receptors
Y-shaped molecule w/ 2 identical heavy chains and 2 identical light chains
53
constant (C) regions or chains on B cells
vary little
54
variable (V) regions on B cells
different greatly
- provide antigens specificity
55
how are B cells activated?
when paratope on variable region of antigen receptor binds to the epitope on the antigen
56
antibody/immunoglobulin
soluble form of the protein secreted by cells
57
3 functions of complement system
1. opsonization
2. membrane attack complex
3. enhance inflammation
58
difference between antibodies and antigen receptors
- antibodies: same Y shape but are secreted
- antigen receptors: membrane-bound
59
composition of T cell receptor
2 different polypeptide chains (a and B)
- tips of chains form variable region, rest is constant region
60
where do T cells bind
to epitope of antigen fragments displayed/presented on host cell
61
major histocompatibility complex (MHC) molecules
cell-surface proteins that are bound to antigen fragments
- host proteins that display antigen fragments on cell surface
62
how are cells infected
1. bacterium engulfed by phagocytosis into a dendritic cell and is encased in a phagosome
2. lysosomes fuse w/ phagosome and digest bacterium
3. immunodominant epitopes are associated with MHC and presented on cell surface
63
antigen presentation
MHC molecules bind/transport antigen fragments to cell surface
64
what can a T cell bind to
both the antigen fragments and the MHC molecule
65
4 characteristics of adaptive immune system
1. immense diversity of lymphocytes and receptors
2. self-tolerance: doesn't react against own molecules/cells
3. B/T cells proliferate after activation
4. immunological memory
66
how does the immune system assemble millions of different antigen receptors from a small number of parts
by combining variable elemnts
67
what does an immunoglobulin (Ig) gene encode
light chain of the B cell receptor
68
what can many different chains be produced from
the same gene by rearrangement of the V, J, and C regions
69
recombinase enzyme complex
acts randomly to connect different V and J segments in each B cell
70
rearrangement of chains/segments
- permanent
- passed on to daughter cells when lymphocyte divides
71
what are rearranged genes transcribed and translated to produce
unique antigen receptors
72
what are antigen receptors generated by
random rearrangement of DNA
73
what are lymphocytes tested for
self-reactivity
- if they don't pass the test = apoptosis (programmed cell death)
74
are there a few or many lymphocytes with antigen receptors for any particular epitope?
few
- in lymph nodes, antigen is exposed to steady stream of lymphocytes until match is made
75
what does the binding of a mature lymphocyte to an antigen initiate
events that activate the lymphocytes
76
how many different B and T cell receptors
- 1 million B
- 20 million T
77
activated lymphocytes lead to what?
clonal selection - clones made, become effector cells - act immediately against the antigen
78
plasma cells
effector cells that secrete antibodies
79
memory cells
effector cells can become memory cells that can give rise to effector cells if same antigen is encountered again
80
2 types of effector B cells
plasma and memory
81
2 types of effector T cells
helper and cytotoxic
82
purpose of antibodies
tag original antigen molecules and mark them for destruction
83
what is immunological memory responsible for
long-term protections against diseases
84
primary immune response
first exposure to specific antigen
85
secondary immune response
memory cells facilitate a faster, more efficient response from a reservoir of T and B memory cells
86
what can defenses provided by B and T lymphocytes be divided into
1. humoral immune response
2. cell-mediated immune response
87
humoral immune response
antibodies help neutralize or eliminate toxins and pathogens in blood and lymph
- B cells, plasma cells
88
cell-mediated immune response
specialized T cells destroy affected host cells
89
what does helper T cell activate
- humoral immunity
- cell-mediated immunity
90
antigen presenting cells
- class I MHC
- class II MHC
91
antigen-presenting cell
antigen must be displayed on surface
- binds antigen to receptor on helper T cell
92
class II MHC
provide molecular signature by which antigen-presenting cells are recognized
93
when happens when antigen receptors on the surface of helper T cells bind to the antigen and the class II MHC molecule
cytokine signals are exchanged between the two cells
- helper T cell is then activate
94
what happens when helper T cell is activated
proliferates, and forms clone of helper T cells, then activates appropriate B cells
95
what can antigen-presenting cells be
dendritic cell, macrophage, B cell
96
what makes a cell an antigen presenting cell
class II MHC
97
example of cytokines
interleukin-1 and interleukin 2
- allow cells to talk to each other
98
is innate or adaptive immunity faster
innate
99
TLR3
binds dsRNA
100
TLR4
lipopolysaccharides found on many bacterial cells
101
TLR5
bacterial flagella
102
CD4 function
protein that checks out MHC 2 molecule to determine if it is actually an antigen-presenting cell
