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Biochemistry > microbiology quiz chapter 14 and chapter 15 > Flashcards

microbiology quiz chapter 14 and chapter 15 Flashcards

1
Q

what are activated complement proteins play a part in eliminating in eliminating microbial invaders from a host ?

A

Phagocytosis
Inflammation
Interferons
Fever

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2
Q

the complement system comprises a group of blank in the bloodstream

A

proteins

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3
Q

the complement system reacts

A

in a cascade

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4
Q

complement proteins are found in

A

serum

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5
Q

when is the classical complement pathway activated

A

when C1 binds to the antibody in an antigen body complex

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6
Q

C3 convertase cleaves C3 into

A

C3a and C3b

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7
Q

what role does C3b play

A

C3b binds to the surface of microorganisms and phagocyte receptors

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8
Q

what do both the classical and alternative complement pathways create

A

C3 convertase

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9
Q

the membrane attack complex kills cells by

A

creating holes in the cell membrane

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10
Q

what are 3 primary functions of complement activation are

A

enhancing phagocytosis, causing inflammation, and killing target cells

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11
Q

what are the following events that can occur after complement activation

A

cytolysis
opsonization
inflammation
enhanced phagocytosis

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12
Q

what is opsonization?

A

when complement enhances phagocytosis of bacterium.

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13
Q

What does the complement factors C5b+C6+C7+C8 make up a membrane attack complex result in

A

cytolysis

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14
Q

true or false : Complement factors are named in the order in which they function.

A

false

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15
Q

true or false : mitochondria contain hydrolytic enzymes

A

false

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16
Q

what are the precursors to macrophages

A

monocytes

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17
Q

what type of cell is capable of phagocytosis

A

neutrophils and macrophages

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18
Q

true or false is phagocytosis apart of the body’s innate immune defense

A

true

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19
Q

Is the complement system apart of the specific immune response

A

false

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20
Q

phagocytes are not attracted to

A

enzymes released by lysozomes

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21
Q

name the process by which phagocytes move toward microbial products?

A

chemotaxisis

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22
Q

true or false: Complement factor C3b coats a bacterium and binds to C3b receptors on phagocytes, making the bacterium more susceptible to being phagocytized.

A

true

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23
Q

what contains hydrolytic enzyme to digest foreign bacteria

A

lysosome

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24
Q

how are microbes killed and digested in the phagolysosome

A

by hydrolytic enzymes

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25
Q

how can phagocytosis be enhanced using immunological medications

A

activated complemented proteins

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26
Q

after being engulfed a microbe is found within where

A

a phagosome

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27
Q

the microbe is digested within the phagocyte by enzymes delivered by

A

a lysozyme

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28
Q

true or false : If a bacterium could escape from a phagosome, it would be able to resist digestion by that phagocyte.

A

true

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29
Q

which of the following are antimicrobial substances are not part of our body first line defenses

A

antibodies

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30
Q

which of the following is part of the body’s sensor systems ?

A

complement proteins

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31
Q

is it possible for one host to be resistant to infection by a pathogen that can normally cause disease in a different host

A

true

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32
Q

which of the following is part of the body’s adaptive defensive

A

b cells

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33
Q

which event occurs in the early stages of inflammation

A

chemical medicators and cytokines are released from injured cells

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34
Q

what is the function of selectins

A

They promote sticking of neutrophils to the inner vessel wall

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35
Q

Which role does histamine play during inflammation?

A

It leads to vasodilation.

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36
Q

. Margination occurs when neutrophils stick to the lining of the endothelium.

A

true

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37
Q

tissue injury leading to inflammation can be due to

A

chemical injury
infection
mechanical energy

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38
Q

the four classic signs and symptoms of inflammation are

A

pain
redness
heat
swelling

not chills

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39
Q

what are the symptoms of inflammation due to

A

vasodilation

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40
Q

which of the following is not a function of inflammation

A

activate the complement system

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41
Q

describe these pattern recognition receptor functions

interferons
RLRs
TLRs
NLRs

A

Interferons these proteins are often secreted when viral RNA is detected which signals neighboring cells to express antiviral proteins.

RLRs These proteins are found in the cytoplasm and can detect viral RNA

TLRs These receptors are found anchored in sentinel cells like macrophages and dendritic cells.They can bind to foreign structures like dsRNA, ssRNA and some bacterial DNA fragments

NLRs These proteins are found in the cytoplasm and can detect bacterial components.

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42
Q

Which of the following are considered physical (versus chemical) factors that contribute to the skin and mucous membranes protective role against infection?

A

flushing of urinary tract
Mucociliary escalator
layers of cells

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43
Q

what are the true statements about fever induction and outcomes

A

fever is induced by cytoskines called pyrogens

fever inhibits bacteria from growing by inhibiting their metabolism

fever usually results when macrophages detect microbial invaders and release pro inflammatory cytoskines

pyrogens have an effect by acting on a certain part of the brain

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44
Q

what is not true about normal microbiota

A

Disruption of the normal microbiota has little effect on the host.

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45
Q

Which of the following statements about innate immunity are FALSE?

A

macrophages must become activated to function

mucous membrane are protected by keratin

lymphocytes form part of the first line of defense

fever inducing cytoskines are called pyroptosins

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46
Q

true or false:, IFN stands for interferon, molecules produced in response to a viral infection

A

true

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47
Q

how is the viral rna detected

A

RIG like receptors
RLRs

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48
Q

After producing IFN what happens to the cell

A

it is
is destroyed as a result of the virus infection.

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49
Q

when IFN made by one cell attaches to receptors on a second cell, what happens to that cell

A

makes antiviral proteins that when activated, degrade mRNA and prevent viral replication.

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50
Q

Once a cell detects viral RNA and produces IFNs, a sequence of events occurs. Place these steps in the correct order.

A

IFN diffuses out of the infected cell and attaches to receptors on healthy neighboring cells.

IFN stimulates healthy neighboring cells to express inactive antiviral proteins (iAVPs).

iAVPs become activated by the presence of viral dsRNA in the newly infected cell

Activated AVPs degrade mRNA, stopping protein synthesis and causing apoptosis of newly infected cell

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51
Q

How are apoptosis, pyroptosis and necroptosis the same?

A

They all lead to the death of the affected cell.

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52
Q

chapter 15 : what does the adaptive immune response involve

A

involves memory of antigens from previous exposure.

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53
Q

what is the responsibility of T cells

A

are responsible for cell-mediated immunity.

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54
Q

what are antigens

A

are molecules that can be recognized by B or T cells.

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55
Q

After repeated exposure to foreign material, innate immu

A

continues to react the same way.

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56
Q

what with antigen fragments displayed on their surfaces are known as antigen-presenting cells (APCs).

A

macrophages

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57
Q

When activated by antigen-presenting cells, helper T cells release what cytokine that activates B cells and cytotoxic T cells?

A

Interleukin-2

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58
Q

Cytotoxic T cells know that a cell is infected because

A

that cell has antigens from the disease-causing microbe on its surface.

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59
Q

B cells differentiate into ______, which make antibodies.

A

plasma cells

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60
Q

The immune system responds more quickly to second exposure to an antigen because

A

memory B cells are produced during the first response.

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61
Q
  1. Cytotoxic T cells kill target cells by
A

exposing them to chemicals that induce apoptosis.

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62
Q

A child with a genetic disorder that does not allow immature B cells to develop would therefore not be able to make

A

antibodies.

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63
Q

. Antigen-presenting cells release what cytokine to activate helper T cells?

A

Interleukin-1

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64
Q

he antibody-producing progeny of an activated B cell are called

A

plasma cells

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65
Q

There are no antigens that can stimulate B cells without T cell help.

A

false

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66
Q

. T-dependent antigens

A

characteristically have a protein component

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67
Q

true or false : Antigen fragments are presented at the surface of macrophages along with self proteins.

A

true

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68
Q

how does a helper T cell activated

A

by an antigen presenting cell

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69
Q

An antigen-presenting cell presents antigen to a helper T cell on its surface using

A

a class 2 molecule on MHC molecule

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70
Q

After a B cell is activated to form plasma cells, those plasma cells each produce different antibodies

A

false

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71
Q

The process of antibody-dependent cellular cytotoxicity (ADCC) allows ______ cells to bind to antibody-coated host cells that may have viral proteins in their plasma membrane in order to kill them, inducing apoptosis and limiting viral spread.

A

natural killer

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72
Q

what is the difference between cytoxic T cells and helper T cells

A

Cytotoxic T cells recognizes antigens presented in mhc class 1 on molecules

cd8 T cells
not targeted by HIV
Realeses death packages

responds to endogenous antigens

helper T cells
CD4 T cells
targeted by HIV
Release cytoskines
Responds to exogenous antigens
recognizes antigens on MHC class 2 molecules

73
Q

which is not a matching pair

A

peyer patchess and skin

74
Q

how does negative selection occur in B and T lymphocytes

A

when cells binds to self antigens too strongly

75
Q

Why is the process of gene rearrangement used in creating antibodies and T-cell receptors (TCRs) so important?

A

Without it, we would need a single gene for every antibody and TCR required to mount all the possible responses needed during our lives

76
Q

Clusters of differentiation (CD) molecules are important because they

A

allow us to differentiate between cells that may look identical by microscopy.

77
Q

match each antibody class with each description

IgA
IgM
IgG
IgE
IgD

A

IgA Most abundant class overall, but mainly found in mucosal secretions. Generally found as a dimer.

igM First class produced in primary response. Forms a pentamer. Helps activate complement through the classical pathway.

IgG Main class found in blood. Only class that can cross the placenta. Found as a monomer.

igE Binds via Fc region to mast cells/basophils. Involved in allergic responses and responses to parasites

igd Involved in maturation of B lymphocytes and antibody responses, but function is largely uncharacterized.

78
Q

Which of the following are secondary lymphoid organs (areas where mature lymphocytes become activated)?

A

Lymph nodes
Peyer’s patches
Tonsils
Spleen

79
Q

Which of the following is a primary lymphoid organ

A

bone marrow

80
Q

Helper T cells secrete ______ to stimulate the proliferation of B cells.

A

cytokines

81
Q
A
82
Q

Helper T cells interact with target cells by recognizing

A

antigen-MHC protein complexes.

83
Q

Which of the following are antigen-presenting cells?

A

Macrophages and B cells are both APCs.

84
Q

Which of the following cells can be a target for cytotoxic T cells?

A

Transplanted cells.
Virus-infected cell.
Cancer cell

85
Q

true or false:
Apoptosis occurs in infected host cells, as well as during positive and negative selection in lymphocyte development

A

true

86
Q

In addition to perforins, what else is secreted by cytotoxic T cells?

A

proteases (e.g. granzymes)

87
Q

true or false: A person deficient in cytotoxic T cells may be more susceptible to developing cancer.

A

true

88
Q

Antigenic fragments are complexed with ______ and displayed on the surface of the infected cell.

A

mhc class 1 molecules

89
Q

Cytotoxic T cells cause death of infected cells by

A

releasing cytotoxins, perforins, and enzymes that destroy the cell.

90
Q

Cytotoxic T cells recognize

A

viral antigens and class I MHC molecules

91
Q

what are molecules that stimulate response in T and B cells

A

antigens

92
Q

surface receptors on immune system cells function in

A

cell development
communication
identification of self/non-self molecules

93
Q

what is the role of helpwer T cells

A

stimulate B cells and other T cells

94
Q

function of helper T cells

A

function in both cell-mediated and humoral immunity.

95
Q

All of the following cells have class II MHC receptors on their surface EXCEPT

A

red blood cells

96
Q

Antigen-presenting cell

A

may be dendritic cells.
may be macrophages.
All of the answer choices are correct.
present antigen fragments on their surface.
may be B cell

97
Q

true or false;A helper T cell must be activated before it can stimulate a B cell to produce antibody.

A

TRUE

98
Q

Both antigen-presenting cells and B cells have class II MHC receptors on their surface

A

true

99
Q

B cells differentiate into plasma cells and

A

memory cells

100
Q

After a B cell is activated to form plasma cells, those plasma cells each produce different antibodies.

A

false

101
Q

toll like receptors are only capable of recognizing

A

they are capable of recognizing antigen epitopes presented on major histocompability MHC moecuoes

102
Q

how are macrophages and neutrophills different ?

A

macrophages and neutrophills are both phagyotic cells but macrophages reside in the tissues and neutrophills typically in the blood.

103
Q

how does toll like receptors binding to macrophages help the immune response

A

These secreted molecules help bind pathogens and then direct them to receptors on the immune system cells that can eliminate them from our systems.

104
Q

the voices of the cell that carry messages are called what

A

cytokines

105
Q

what are the two functions that phagocytes serve

A

Engulfment/destruction of foreign cells AND alerting the other cells of the immune system to an invader.

106
Q

what is the definition of neutralization

A

Antibodies fill the surface receptors on microbe to prevent attachment to the host

107
Q

what is the definiton of complement system activation

A

Immune complexes activate complement proteins, leading to inflammation and production of MACs

108
Q

what is the definition of immobilization and prevention of adherence

A

Antibodies bind to flagella preventing movement or to pili preventing attachment of bacteria

109
Q

what is cross linking ?

A

Formation of large Ab-Ag complexes as a result of the Ab binding two separate antigens

110
Q

what is Antibody-dependent cellular cytotoxicity (ADCC)

A

IgG molecules attach to a cell targeting it for attack by a NK cell

111
Q

if a pathagen avoid binding by the complement C3B what would protect itsef from

A

opsonization

112
Q

A physician is attempting new therapies for HIV patients who are suffering from an impaired immune response. He decides to try using a recombinant form of colony-stimulating factor cytokine (CSF). Why?

A

CSF will help to stimulate the production of new lymphocytes, the very cells that are affected by HIV. This may help to keep the patients’ immune responses “normal” for a period of time.

113
Q

what is the main phagocytes in circulation

A

neutrophils

114
Q

what is involved in inflammation and allergic reactions

A

basophills

115
Q

what Displays no antigen specificity but are active against tumor and virally infected cell

A

natural killer cells

116
Q

what are Phagocytic cells that leave circulation and differentiate into macrophages

A

monocytes

117
Q

what is the accumulation oif dead cells and neutrophils

A

pus formation

118
Q

what does vasodilation and incrreased blood flow cause

A

heat and redness

119
Q

what causes leaky blood cells and phagocyte cells migration

A

swelling and pain

120
Q

what is the effect of chemical nerves

A

pain

121
Q

what is the difference between innate and adaptive immunity?

A

Innate immunity is routine protection present at birth

Adaptive immunity develops throughout life as body is exposed to microbes or foreign material

122
Q

describe how innate factors destroy invadors

A

Interferon (IFN) secreted with viral infection

Phagocytes engulf microbes or cell debris by phagocytosis

Inflammatory response is coordinated

Fever interferes with pathogen growth and enhances other immune responses

123
Q

describe the overview of the innate immune defenses

A

Sentinel cells use pattern recognition receptors (PRRs) to identify unique microbial components

Complement system found in blood and tissue fluid

124
Q

dexcribe the antimicorbial substances peroxidases lysozyme AMP and lactoferrin

A

Lysozyme degrades peptidoglycan

Peroxidases form antimicrobials; break down hydrogen peroxide

Lactoferrin and transferrin bind iron

Antimicrobial peptides (AMPs)
Defensins form pores in microbial membranes

125
Q

what are the roles of the granulocytes neutrophils basophils and eosinphils

A

Neutrophils engulf and destroy bacteria; granules contain enzymes
, antimicrobials; also called PMNs, increase in number during infection

Basophils involved in allergic reactions, inflammation; granules contain histamine
Mast cells similar; found in tissues

Eosinophils fight parasitic worms; involved in allergic reactions; granules contain antimicrobials and histaminase

126
Q

what is the mononuclear phagocyte system compose dof

A

Includes monocytes (circulate in blood) and cell types that develop as they leave bloodstream

Macrophages differentiate from monocytes

Sentinel cells found in nearly all tissues

127
Q

what is the responsibility of dendritic cells

A

Sentinel cells, function as “scouts”

Engulf material in tissues, bring it to cells of adaptive immune system for

“inspection”
Usually develop from monocytes

128
Q

what is the main responsibility of lymphocytes

A

Responsible for adaptive immunity
B cells, T cells highly specific in recognition of antigen
Generally reside in lymph nodes, lymphatic tissues
Innate lymphoid cells (ILCs) lack specificity

Can promote inflammatory response
Natural killer (NK) cells destroy certain types of cells

129
Q

what is the defintion of chemokines colony stimulating factors and interferons and interleukins,and tumor necrosis factor

A

Chemokines: chemotaxis of immune cells
Colony-stimulating factors (

CSFs): multiplication and differentiation of leukocytes

Interferons (IFNs): control of viral infections, regulation of immune responses

Interleukins (ILs): produced by leukocytes; important in innate and adaptive immunity

Tumor necrosis factor (TNF): inflammation, apoptosis

130
Q

what is a cytoskine storm

A

is a potentially deadly overproduction of cytokines that can occur during an immune response to certain pathogens, including COVID-19

131
Q

describe the pattern recognition receptors DAMP
PAMP and MAMPs

A

Microbe-associated molecular patterns (MAMPs) detected by PRRs

Include cell wall components (peptidoglycan,
PAMPs are pathogen-associated, but not exclusive to pathogens

Damage-associated molecular patterns (DAMPs) indicate cell damage

132
Q

describe the three types of cell death apoptosis pyroptosis and necrosis

A

Necrosis: traumatic cell death due to damage
Self-destruction of host cells

Apoptosis: programmed cell death; does not trigger inflammatory response

Pyroptosis and necroptosis: types of cell death that triggers an inflammatory response that sacrifices infected cells

133
Q

describe acute inflammation and what happens when acute inflammation fails

A

acute inflammation is short term mostly neutrophils and macrophages that kill dead cells by ingesting dead cells and debris

If acute fails, chronic inflammation results; macrophages, giant cells accumulate, and granulomas form

134
Q

describe the definition of cellular changes
a process called diapedesis
absceses
and what makes pus

A

Cellular changes - Cytokines cause endothelial cells of blood vessels to “grab” phagocytes in the bloodstream

Phagocytes squeeze between the cells of the dilated vessel, and move into tissues in a process called diapedesis

Dead neutrophils accumulate; along with tissue debris, make up pus
A localized collection of pus within a tissue is called an abscess

135
Q

describe vascular changes

A

Vascular changes - The diameter of local blood vessels increases due to the action of histamine and other inflammatory mediators

Results in greater blood flow to the area, causing the heat and redness associated with inflammation

136
Q

describe the process of exudate

A

Changes in the endothelial cells of capillaries allow fluid, called exudate, to leak from the blood vessels and into the tissue
Exudate is a protein-rich fluid that contains transferrin, complement system proteins, antibodies, and other substances to counteract invading microbes

Accumulation of exudate causes swelling and pain associated with inflammation

137
Q

what is inflammation the purpose of inflammation and the conclusion of inflammation?

A

Infection or tissue damage results in inflammation

Purpose is to contain site of damage, localize response, eliminate invader, and restore tissue function

Results in swelling, redness, heat, pain, sometimes loss of function

138
Q

what does pattern recognition receptors trigger

A

Pattern recognition receptors (PRRs) trigger

Detect MAMPs, DAMPs
Host cells release inflammatory mediators (cytokines, histamine)

139
Q

what are the characteristics of neutrophils

A

Neutrophils act as “SWAT team”

Rapid response; move into area and eliminate invaders

More powerful than macrophages, but short life span of 1 to 2 days in tissues

Die once granules used
Kill microbes via phagocytosis and release of granule content

allowing enzymes and peptides from granules to destroy them

140
Q

characteristics of macrophages

A

Macrophages are everyday “beat cops”
Phagocytize dead cells, debris, destroy invaders
Live weeks or months; regenerate lysosomes

Activated macrophages - response to cytokines
M1 macrophages have greater killing power

M2 macrophages lessen inflammation

Macrophages, giant cells, T cells form granulomas
Wall off organisms or material resistant to destruction

Important sentinel cells; alerts other immune cells

141
Q

describe phagocytosis and exocytosis

A

Phagocytes engulf and digest material, pathogens

Chemotaxis: phagocytes recruited by chemoattractants

Recognition and attachment: direct (receptors bind mannose) and indirect (binding to opsonins)

Engulfment: pseudopods surround, form phagosome

Phagosome maturation and phagolysosome formation: directed by TLRs; fuse with lysosomes containing enzymes

Exocytosis: vesicle fuses with cytoplasmic membrane, expels remains

142
Q

describe the complement system

A

Regulation prevents host cells from activating complement system

Molecules in host cell membranes bind regulatory proteins that inactivate C3b, preventing opsonization or triggering of alternative pathway

143
Q

describe the pattern recognition receptors

A

Allow body to “see” signs of microbial invasion; lead to cytokine secretion

Microbe-associated molecular patterns (MAMPs) detected by PRRs

PAMPs are pathogen-associated, but not exclusive to pathogens

Damage-associated molecular patterns (DAMPs) indicate cell damage

144
Q

describe toll like receptors

A

Anchored in membranes of sentinel cells

Surface TLRs monitor extracellular environment
TLRs in phagosomal or endosomal membranes of organelles characterize ingested material

Specific for distinct MAMPs

Dendritic cells have both TLRs and CLRs (C-type lectin receptors)

145
Q

describe rig and nod like receptors

A

RIG-like receptors (RLRs) in cytoplasm detect viral RNA
Often double-stranded; no cap
NOD-like receptors (NLRs) in cytoplasm detect microbial components or cell damage

146
Q

describe the interferon process

A

PRRs detect viral RNA; cell produces interferon (IFN)
Interferon causes neighboring cells to express inactive antiviral proteins (iAVPs)

iAVPs activated by viral dsRNA

Degrade mRNA, stop protein synthesis, infected cells undergo apoptosis

147
Q

what are the three pathways for activation

A

Alternative pathway triggered when C3b binds to foreign cell surfaces (C3 unstable, so some C3b always present)

Lectin pathway: pattern recognition molecules (mannose-binding lectins, or MBLs) bind to mannose of microbial cells, interact with complement system components

Classical pathway: activated by antibodies bound to antigen, which interact with complement system

148
Q

what are the outcomes of activation of the complement system

A

Opsonization: C3b binds to bacterial cells and foreign particles, promotes engulfment by phagocytes that attach to opsonins (like C3b)

Inflammatory Response: C5a attracts phagocytes to area; C3a and C5a increase permeability of blood vessels, induce mast cells to release cytokines

Lysis of Foreign Cells: membrane attack complexes (MACs) formed by proteins C5b, C6, C7, C8, and C9 molecules assembling in cell membranes of Gram-negatives

149
Q

describe natural killer cells

A

Lysis of Foreign Cells: membrane attack complexes (MACs) formed by proteins

C5b, C6, C7, C8, and C9 molecules assembling in cell membranes of Gram-negatives

NK cells bind, deliver perforin- and protease-containing granules to cell, initiating apoptosis

Also recognize host cells lacking MHC class I

150
Q

describe lymphocyte development

A

Negative Selection of Self-Reactive B Cells
B cells are exposed to “self” in bone marrow; if bind, induced to undergo apoptosis

This negative selection removes most B cells; critical for preventing immune system from attacking body

Positive and Negative Selection of T Cells
Positive selection: T cells must recognize MHC
Eliminated if unable to recognize

Negative selection: T cells also eliminated if recognize “self” peptides presented on MHC molecules

151
Q

describe lymphocyte development

A

B cells mature in bone marrow, T cells mature in thymus

Gene rearrangement generates diversity
Process similar for B cells and T cells

152
Q

describe t independent antigens

A

can activate cells without aid TH cells

Molecules with numerous identical evenly spaced epitopes (for example, polysaccharide capsules) are bound by clusters of B-cell receptors

Lipopolysaccharide (LPS), a component of the outer membrane of Gram negative bacteria, is also a T-independent antigen

153
Q

describe the characteristics of the secondary immune response

A

Receptors already fine-tuned through affinity maturation
Antibodies coded by these cells bind antigen effectively

When activated, some quickly become plasma cells, producing IgG or IgA due to class switching

Proliferating cells again undergo affinity maturation, generating even more effective antibodies
Mediated by memory cells

Significantly faster, more effective than primary
Pathogens usually eliminated before causing harm
Vaccination exploits this natural phenomenon

154
Q

describe the primary response

A

Plasma cells undergo apoptosis after several days, but are replaced as long as antigen is present

Antibody produced by those plasma cells

Some of the B cell clones become memory B cells, which are long-lived even in the absence of antigen

retains some of the antigens, maintaining memory of the response

Once the antigen is cleared, the antibody response decreases

activated lymphocytes undergo apoptosis

155
Q

describe class switching

A

B cells are originally programmed to produce plasma cells that secrete IgM

As cells multiply some are induced to differentiate into plasma cells that secrete other antibody classes

B cells in lymph nodes usually switch to IgG
B cells in MALT switch to IgA

156
Q

describe affinity maturation

A

Form of natural selection among proliferating B cells
Spontaneous mutations occur in multiplying B cells resulting in slight changes in B-cell receptor

B cells that bind antigen longest are most likely to proliferate

157
Q

describe the eveloution of the primary response

A

When the few naive B cells that recognize a particular antigen are activated, they multiply to generate a population of clones

Some form antibody-secreting plasma cells; produce IgM

Others form a region the secondary lymphoid organ called a germinal center (GC) TH cells direct activated B cells to optimize their response

resulta in class switching including affinity maturation

158
Q

describe the immuglobiin reesponses

A

IgE barely detectable in serum; most is tightly bound via Fc region to basophils and mast cells

igD Involved with development and maturation of antibody response

IgM
First class produced during primary response
Principal class produced in response to some T-independent antigens

IgG
Maternal IgG protects fetus and newborn
Degrade gradually over 6 month period
Infant begins producing its own antibodies
IgG found in colostrum (first breast milk); absorbed by newborn’s intestinal tract

159
Q

what are the characterisitcs of antibodies

A

Antibodies (immunoglobulins) have Y-shaped structure called an antibody monomer

Variable region at the end of each arm gives the antibody its antigen-binding specificity

The remaining part is the constant region
The two identical arms are called the Fab region
Stem is the Fc region

160
Q

descrine b cel activation

A

Activated B cell proliferates and gives rise to antibody-secreting plasma cells as well as memory cells

161
Q

describe b cell receptors

A

Composed of four polypeptide chains—two duplicate copies of a heavy chain and two duplicate copies of a light chain

Disulfide bonds link together these chains
Forms a Y-shaped structure with two identical arms and a stem

The part farthest from the cell surface is a variable region that binds to the antigen

The part closest to the cell surface is the constant region

162
Q

the role of macrophages activation in TH cells

A

Activated macrophages can fuse together to form giant cells; form granulomas that wall off the invader, preventing its escape

if a TH cell recognizes one of the peptides, it delivers cytokines that activate the macrophage

macrophages engulf and degrade invading microbes TH cells activate macrophages to make them more potent

163
Q

effector function of TC cells

A

TC cells can induce apoptosis in cancerous cells because they make abnormal proteins however, peripheral tolerance mechanisms referred to as immune checkpoints often stops that from happening

TC cell binds to a presented peptide it releases proteases and perforin; forms pores in the target cell membrane
The proteases enter the target cell through the pores and induce apoptosis

tc cells can survive and go into other targets

164
Q

activation of T cells

A

Dendritic cells activate T cells
Reside in peripheral tissues (skin, mucosa)
Gather materials via phagocytosis, pinocytosis
Can send extensions between epithelial cells of mucosal barriers and sample material in respiratory tract and lumen of intestine

Toll-like receptors (TLRs) and others recognize pathogens
If pathogens detected, cell takes up more material
Travels to secondary lymphoid organs; matures
Produces co-stimulatory molecules signaling “danger”
Presents antigens on both MHC class I and class II

T cell is activated by dendritic cell with co-stimulatory molecules

T cell becomes anergic or develops into T reg cells if no co-stimulatory molecules
Mechanisms of tolerance

165
Q

what are two types of mhc molecules

A

Two types of MHC molecules can present antigen
MHC class I and MHC class II
Cytotoxic T cells have CD8 marker and only recognize antigens presented on MHC class I

Helper T cells have CD4 marker and only recognize antigens presented on MHC class II

166
Q

describe the types of lymphocytes

A

Immature lymphocytes lack fully developed antigen-specific receptors
Naïve lymphocytes have receptors; have not yet encountered appropriate antigen

Activated lymphocytes have bound antigen and received confirmation, are able to proliferate

Effector lymphocytes are descendants of activated TH cells and Tc cells

Memory lymphocytes are long-lived descendants of activated lymphocytes; responsible for rapid secondary response if antigen encountered again

167
Q

what are secondary lymphoid organs

A

Lymph nodes, spleen, tonsils

Mucosal immunity prevents microbial invasion via mucous membranes

Lymphoid tissues under skin are skin-associated lymphoid tissue (SALT)

168
Q

characteristics of adaptive immunuty

A

Develops most effective means to eliminate invader
Lymphocytes recognize foreign material (antigen) and proliferate, leading to adaptive immunity

Characteristics of adaptive immunity
Molecular specificity

Immunological Memory
Stronger response to re-exposure
Vaccination relies upon this ability

Immune Tolerance
Must distinguish between “healthy self” and “dangerous”

169
Q

cell meditated vs hummoral immunity

A

Humoral Immunity
Eliminates microbial invaders and toxins in the blood or tissue fluids
Involves B lymphocytes (B cells);
Programmed to produce Y-shaped proteins called antibodies
These bind to specific antigens, marking them as an invader to be eliminated

Cell-Mediated Immunity (CMI)
Deals with invaders residing in a “self” cell
Invaders include viruses and bacteria
Relies on T lymphocytes (T cells ); T indicates they mature in the thymus
Two types of T cells help eliminate antigens; differ in surface proteins, called CD markers

170
Q

describe the three types of receptors

A

T-cell receptors (TCRs) only bind an antigen “presented” by one of the body’s own cell
Binding is guided by a surface molecule called a CD marker
Cytotoxic T cells have CD8 marker
Helper T cells have a CD4 marker

B-cell receptors (BCRs) are membrane-anchored antibodies

A region of the receptor called an antigen-binding site is responsible for that recognition
The antigen receptors on a single lymphocyte are identical; all recognize the same antigen

171
Q

describe the types of tolerance

A

Immune tolerance, prevents inappropriate adaptive immune responses from damaging the body’s own tissues

Provided by two sequential processes:
Central tolerance - as lymphocytes mature (T cells in the thymus and B cells in the bone marrow), immature T and B cells that recognize “self” molecules are eliminated

Peripheral tolerance - prevents mature T and B cells that were not eliminated during central tolerance from reacting against self or other harmless molecules

172
Q

describe peripheral tolerance

A

Naïve lymphocyte: never encountered antigen; cannot react until it receives confirming signals

Activated lymphocyte: has received confirming signals, proliferates, differentiates

Effector lymphocytes: short-lived, primary response

Memory lymphocytes: long-lived, activated more quickly to provide a secondary response

The first adaptive immune response to a particular antigen is called the primary response

Additional encounters with the same antigen result in a faster and more effective reaction called the secondary response

Memory lymphocytes are responsible for the secondary response

173
Q

descrobe cell meditated t cell actovation

A

Immune response cannot begin until a lymphocyte becomes activated
Dendritic cells help activate the naive T cells

Present pieces of the antigen
Producing surface proteins, called co-stimulatory molecules if the antigen being presented is microbial or otherwise represents “danger”

If a T cell TCR binds an antigen presented by a dendritic cell that also has co-stimulatory molecules, T-cell activation may result

174
Q

t cell activation

A

a cytotoxic t cell proliferates
tc cell can induce the self cell to undergo aptosis

can become th cells deliver cytokines to macrophages and B cells, thus activating them

and also produce ctyokines

175
Q

describe primary lymphoid organs

A

Include bone marrow, thymus
Organs where lymphocytes develop

Hematopoietic stem cells reside in bone marrow; give rise to all blood cells including lymphocytes

B cells mature in bone marrow

T cells migrate to the thymus

176
Q

t independant vs t dependant antigens

A

An antigen that elicits immune response is immunogenic

T-dependent antigens - B cells that recognize them cannot be activated without TH cell help

T-independent antigens - activate B cells without TH cell help

177
Q

what are the protetivr outcomes of antigen body building

A

Neutralization: prevents toxins, viruses from binding

Opsonization: enhancement of phagocytosis

Complement system activation: classical pathway
Immobilization and prevention of adherence: binding to bacterial flagella or pili interferes
Cross-linking: two arms of antigen bind separate antigens

Antibody-dependent cellular cytotoxicity (ADCC): targets cell for destruction by natural killer (NK) cells

178
Q

hummoral immunity b cell activatiobn

A

Once a B cell becomes activated and proliferates many of the clones differentiate to become plasma cells

Plasma cells make antibodies, which are secreted versions of the BCR

If antibodies bind to antigens of microbial cells, toxins, and viruses, they protect the body against the effects of those antigens

179
Q
A

Biochemistry (7 decks)

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