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immunology Flashcards

(53 cards)

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1
Q

How do immune cells recognize pathogens

types of recognition

A

Innate recognition
Adaptive recognition

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2
Q

Innate recognition

A

Each of a small set of receptors recognizes a molecule absent from animals, but common to a type of pathogen

recognition and response rely on traits common to groups of pathogens

look for specific 3d shapes

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3
Q

innate immune system

A

preformed barriers, tissues, cells, proteins that share common strategies across animals

first line of defense

barrier defenses and antimicrobial peptides/proteins
cellular innate defenses
lymphatic system

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4
Q

the innate immune system combined strategies can generate the

A

local inflammatory response

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5
Q

barrier defenses

A

collection of barriers
- walls
physical barrier like the skin
there are already bacteria and fungi on the skin that will compete with pathogens
lysozymes
ingested bacteria can be destroyed by acidic stomach
defensins

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6
Q

defensive barrier proteins that help when pathogens somehow enter body through openings

A

tears, mucus, saliva contain the enzyme lysozyme that attacks the cell walls of bacteria

causes lysis –> burst bacteria

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7
Q

defensins

A

positively charged small peptides that cause lysis

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8
Q

what is an interior physical barrier

A

mucous membranes
acidic pH
enzymes

epithelial lining of the GI tractd

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9
Q

defensins

A

cationic proteins
produced by neutrophils
have 3 functions:
1. neutralize toxins by binding to them and blocjing them from perorming their tasks
2. creating pores on bacterial surface with electrostatic attraction-> results in lyse
3. activate other immune cells

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10
Q

lysozyme

A

enzyme that performs lysis

breaks peptidoglycan layer over bacterial membrane
create pore
water flows in a

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11
Q

barrier defenses- antimicrobial proteins

what antimicrobial proteins exist and what do they do

A

interferons

immediately made by cells that are infected with viruses

move away from cell that made it

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12
Q

what three things can interfurons do

A

signals neighboring cells to destroy any RNA that enter them and reduces protein synthesis

signals neighboring cells to undergo apoptosis

activates immune cells which kill infected cells

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13
Q

so what occurs after viral infection

A

infected cell immediately makes interferons that move away to other cells

virus is able to continue to reproduce for a little

T-cells come and lyse the infected cells

viral load then starts to decrease

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14
Q

complement protein

A

activation of complement occurs when cell is infective

antibodies from adaptive immune system activate cascade of innate proteins that end up in a pore

lyses

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15
Q

innate system cellular defenses

A

done by white blood cells, phagocytes and lyphocytes

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16
Q

phagocytes

A

engulf and digest foreign materials and other specialized coordinate responses

two types called neutrophils and macrophages

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17
Q

all blood cells originate from

A

stem cells in the bone marrow

progenitor cell

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18
Q

dendritic cells

A

strategically positioned at points of entry to the body

engulf invaders and initiate defense responses

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19
Q

toll-like receptors

A

how you recognize non-self

key molecules that alert the immune system to presence of microbial infections

recognize pathogen associated molecular patterns(PAMS) of pathogens

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20
Q

so how do toll-like receptors actually work

A

a ligand(pathogen associated molecular pattern) fits into binding pocket of TLR and activates it

this causes a change in conformation nd activates subsequent protein transcription and translation of defense proteins –> interferons and defensins

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21
Q

inflammatory response

A

used in dealing with infection or tissue damage

bacteria make it through barier defense of skin anad is awaited by white blood cells
first resonders are mast cells and they release tumor necrosis factor, prostaglandins, and histamine which trigger inflammation

histamine diffuse away from mast cells and causes capillaries to become leaky allowing plasma and phagocytes to escape the tisssue

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22
Q

after the inflammatory response causes the capillaries to become leaky, what happens

Study These Flashcards
A

complement proteins and other chemical signals attract phagocytes

neutrophils arrive first, then monocytes

macrophages engulf invaders and are responsible for most of the healing

phagocytes produce cytokines that activate other immune cells

23
Q

lymphatic system

Study These Flashcards
A

sewer pipes

branching system of tiny capillaries containing larger vessels

contain lymph that conssits of fluids that accumulate outside the closed circulatory system

in lymph nodes, lymph is filtered and blood cells inspect it for pathogens

contian white blood cells

24
Q

what two types of DEFENSE mechanisms exist

Study These Flashcards
A

innate defenses and adaptive defenses

25
innate defenses
nonspecific defenses inherited mechanisms that protect thebody from different pathogens rapid and generalized
26
adaptive defenses
specific defenses that protect against specific targets some can evade innate system so second defense slower and highly specific specific to one pathogen at a time
27
what is an antigen
a 3-d foreign shape that is recognized by T cells antigens are proteins on pathogen surfaces that are composed of epitopes antibodies uniquely bind to one epitope of antigens virus can have multiple epitopes
28
antigen presenting cells extracellular pathogens process of linking innate to adaptive immune system
antigen presenting cells include dendrites neutrophils(PMN), macrophages, and B-cells these APCs engulf pathogens, degrade them, and display the antigen fragments on its own protein receptors, MHCII specific helper T cells bind to this MHCII complex by the antigen fragment binding of helper T cell promotes the secretion of cytokines by the antigen-presenting cell(APC) which stimulates proliferation of helper T cell this proliferation produces clones of activated helper T cells these clones have receptors of the same antigen and will also secrete other cytokines that activate B cell and cytotoxic T cells (Tc) with the same antigen specificity
29
major histocompatibility complex proteins
two types MHCI and MHCII
30
Class I MHC pathway
APC can be any cell antigen is intracellular(virus) APC breaks down proteins in the cell and presents little peptides via MHCI complex, to cytotoxic T cells to prove your cell is not infected
31
B cell vs cytotoxic T cell difference
B cell is for humoral immunity, the secretion of antibodies by plasma cells cytotoxic T cells are for cell-mediated immunity which attacks infected cells (MHCI cells)
32
MHC I
MHC I proteins are present on the surface of every nucleated cell in vertebrates it randomly samples cytoplasm to ensure no pathogens are present when cellular proteins are degraded in the proteasome, an MHC I protein may bind a fragment and travel to the plasma membrane to present it cytotoxic T cells can recognize these antigens and if infected, will kill the cell
33
MHC II
found mostly on B cells, macrophages, neutrophils, dendritic cells (apc's) when an antigen is phagocytosed, it is broken down and presented at the surface by MHCII this is then recognized by helper T cells
34
adaptive recognition
uses very specific antigen receptors on mature B or mature T cells slight differences in amino acid sequence of antigen receptors changes whether or not cells can respond to antigens two different branches of response in adaptive immunity: humoral response and cell-mediated response
35
humoral response
antibodies defend against infection in body fluids (secretion of antibodies via B-cells)
36
cell-mediated response
cytotoxic cells defend against infection in body cells (kill signal via cytotoxic T cells and lysis)
37
4 defining characteristics of adaptive immunity
1. specificity 2. diversity 3. distinguish self from non-self 4. memory
38
specificity of adaptive immunity
immune system targets small single amino acid variations in epitopes
39
memory of adaptive immunity
train immune system and recognize pathogens to kill it immediately if it reenters
40
b-cells
provide diversity via variable regions with cutout that allow epitopes to bind uniquely to site of variable region each b cell has its own unique variable region Y shaped with two prongs/antigen binding site
41
what happens when antigen with specific epitope fits in variable region
this activates that specific B-cell which undergoes mitosis and a clonal expansion the b-cell will give rise to cells that secrete an antibody antibodies can recognize specific free antigens as well as antigens on a pathogen's surface
42
T cells
one antigen binding site I shaped
43
how does humoral regulation work the two step regulation
produces antibodies 1. activation of T-helper cell that recognizes antigen 2. activated T helper cell finds B cell that recognizes same antigen
44
step by step of humoral regulation
antigen is taken up by APC and broken down antigen piece is bound to MHCII cell and brought to cell surface where a T helper cell recognizes it cytokines released by APC and t-helper cell, causing t-helper cell to proliferate(clonal expansion) B-cell that engulfed the same antigen will present it via MHCII to surface where a Th cell receptor will recognize it cytokines are released that cause B cell to proliferate and b cells can become memory cells or plasma cells plasma cells will produce antibodies antibodies are identical to B-cell receptors
45
antibody molecules are proteins called
immunoglobulins
46
immunoglobulins
comprised of 2 light chains and heavy chains variable and constant regions bivalent n terminus at binding region BCR
47
two major functions of antibodies
agglutination opsoniation
48
agglutination
sticking microbes together blockes escaoe and infection can't spread
49
opsonization
specific form of phagocytosis recepptor mediated macrophages grab onto antigens with receptors and engulf them
50
two major classes of T cells
T-helper and cytotoxic T-lymphocytes
51
cellular response occurs when
virus invades inside your cell
52
differenec between T-helper and Cytotoxic T-lymphocytes
T-helper: HQ cell that regulates both humoral and cellular immune responses cytotoxic T lymphocytes: function is to kill other cells via lysois
53
general process of cellular response
APC will be virally infected and this virus will be broken down and presented via MHC I on cell surface cytotoxic cell (T cell) recognizes the fragment and proliferates T cell receptoor recognizes antegenic fragment bound to a MHC I protein of a separate infected cell and T cell releases perforin perforin creates pores that result in lysis

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