24 Lecture Presentation

7/27/2019 24 Lecture Presentation

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Copyright 2009 Pearson Education, Inc.

PowerPoint Lectures for

Biology: Concepts & Connections, Sixth EditionCampbell, Reece, Taylor, Simon, and Dickey

Chapter 24 The Immune System

Lecture by Edward J. Zalisko


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Introduction: The Kissing Disease?!?

Mononucleosis (mono)

Caused by Epstein-Barr virus (EBV)

95% of humans infected by adulthood

Infected children show few symptoms

Half of infected adolescents/young adults get mono

Symptoms include

Fever

Sore throat

Swollen lymph glands


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There is no vaccine for mono

There is no effective treatment for mono

Rest, fluids, and pain relievers assist recovery

Mono is almost never fatal


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Mono is spread by saliva

Kissing

Shared dishes or utensils

EBV infects B cells, weakening the immune system

Infections are life-long but rarely cause symptomsagain

An infected person acquires long-lasting immunityagainst EBV

An infected person can spread the disease


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7/86Copyright 2009 Pearson Education, Inc.

INNATE DEFENSESAGAINST INFECTION



24.1 Both invertebrates and vertebrates haveinnate defenses against infection

Innate defensesfirst line of defense

Found in all animals

Includes

Skin Mucous membranes

Phagocytic cells

Antimicrobial proteins

Same response to invaders each time




Invertebrates have only innate immunity Vertebrates have innate and acquired immunity


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Acquired immunity (24.4-15)Innate immunity (24.1-3)

Externalbarriers

Internaldefenses

The lymphatic system (24.3)

Response is the same whether

or not pathogen has beenpreviously encountered

Found only in vertebrates;

previous exposure to pathogenenhances immune response

Antibodies (24.8-10)

Lymphocytes (24.11-14)

Phagocytic cells

NK cells

Defensive proteins

Inflammatory

response (24.2)

Skin/exoskeleton

Secretions

Mucous

membranes




Interferons are proteins produced by virus-infected cells

Interferons help other cells resist viruses

Found only in vertebrates


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Virus

DNA

Makes interferon;is killed by virus

Viral nucleic acid

mRNA

Interferongenesturnedon

Interferonmolecules

1

2

3

Host cell 1

New viruses

Antiviral proteins blockviral reproduction

5

Host cell 24

Interferon stimulatescell to turn on genes

for antiviral proteins

Protected against virusby interferon from cell 1



24.2 The inflammatory response mobilizes innatedefenses

Tissue damage triggers the inflammatoryresponse

The inflammatory response can

Disinfect tissues Limit further infection


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Pin

1 2 3

SwellingSkin surface

Bacteria

Chemicalsignals

Whiteblood cell

Blood vessel

Phagocytes andfluid moveinto area

Phagocytes

Tissue injury; release ofchemical signals such as

histamine

Dilation and increasedleakiness of local blood

vessels; migration ofphagocytes to the area

Phagocytes(macrophages and

neutrophils) consumebacteria and celldebris; tissue heals


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Pin

1

Skin surface

Bacteria

Chemical

signalsWhiteblood cell

Blood vessel

Tissue injury; release ofchemical signals such as

histamine


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2

Swelling

Phagocytes andfluid moveinto area

Dilation and increasedleakiness of local bloodvessels; migration of

phagocytes to the area


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3

Phagocytes

Phagocytes (macrophagesand neutrophils) consumebacteria and cell debris;

tissue heals


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24.3 The lymphatic system becomes a crucialbattleground during infection

The lymphatic system is a network of Lymphatic vessels

Organs

Lymphatic vessels Collect fluid from body tissues

Return it as lymph to the blood

Lymph organs

Such as the spleen and lymph nodes

Are packed with white blood cells that fight infections


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24.3 The lymphatic system becomes a crucialbattleground during infection

As lymph circulates through lymphatic organs it Collects

Microbes

Parts of microbes

Microbe toxins

Transports them to lymphatic organs

Macrophages in lymphatic organs engulf the invaders

Lymphocytes may mount an acquired immune response


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Adenoid

Tonsil

Lymph nodes

Thymus

Right lymphaticduct, enteringvein

Thoracicduct

Appendix Spleen

Thoracic duct,entering vein

Bonemarrow Lymphatic

vessels

Lymphaticcapillary

Interstitial fluid

Blood capillary

Tissue cells

Lymphatic vessel

Valve

Lymph node

Masses oflymphocytes andmacrophages


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Adenoid

Tonsil

Lymph nodes

Thymus

Right lymphatic

duct, enteringvein

Thoracicduct

Appendix Spleen

Thoracic duct,entering vein

Bonemarrow Lymphatic

vessels


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Lymphatic

capillary

Interstitial fluid

Blood capillaryTissue cells

Lymphatic vessel

Valve

Lymph node

Masses of

lymphocytes andmacrophages


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ACQUIRED IMMUNITY


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24.4 The acquired immune response countersspecific invaders

Our immune system Responds to foreign molecules called antigens

The acquired immune system

Reacts to antigens

And remembers an invader


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24.4 The acquired immune response countersspecific invaders

Infection or vaccination triggers active immunity

We can temporarily acquire passive immunityby receiving premade antibodies


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24.5 Lymphocytes mount a dual defense

Two kinds oflymphocytes carry out the immuneresponse

B cells

Secrete antibodies

Mount the humoral immune response

T cells

Attack cells infected with bacteria or viruses

Cell-mediated immune response


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Humoral immuneresponse

Cell-mediatedimmune response

Lymph nodes,spleen, and

other lymphaticorgans

Final maturationof B and T cells inlymphatic organ

Viablood

T cellB cell

Viablood

Antigenreceptor

Thymus

Antigenreceptor

Immaturelymphocytes

Stem cell

Bonemarrow


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24.5 Lymphocytes mount a dual defense

Millions of kinds of B cells and T cells Each with different membrane receptors

Wait in the lymphatic system

Where they may respond to invaders


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24.6 Antigens have specific regions whereantibodies bind to them

Antigens Not usually part of the host

Most are proteins or large polysaccharides on thesurfaces of

Viruses

Foreign cells

Antigenic determinants

Specific regions on an antigen

To which antibodies bind

A tib d A


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Antigenmolecule

Antibody B

molecule

Antibody Amolecule

Antigen-

bindingsites

Antigenicdeterminants

24 7 Cl l l i d f i f


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24.7 Clonal selection musters defensive forcesagainst specific antigens

When an antigen enters the body It activates only a small subset of lymphocytes

Those with complementary receptors

The selected lymphocyte cells multiply into clones ofshort-lived effector cells

Specialized for defending against the antigen that

triggered the response

And into memory cells that confer long-term immunity

24 7 Cl l l i d f i f


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24.7 Clonal selection musters defensive forcesagainst specific antigens

The steps ofclonal selection Primary immune response, clonal selection

Produces effector cells

Memory cells that may confer lifelong immunity

Secondary immune response

Memory cells are activated by a second exposure to thesame antigen

This initiates a faster and stronger response

Animation: Role of B Cells
http://localhost/var/www/apps/conversion/tmp/scratch_5/24_07ARoleOfBCells_A.html


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Primary immune

response

B cells with

different

antigen

receptors

Antigen receptor

(antibody on cell

surface)

1


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Primary immune

response

B cells with

different

antigen

receptors

Antigen receptor

(antibody on cell

surface)

1 Antigen

molecules

2


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Primary immune

response

B cells with

different

antigen

receptors

Antigen receptor

(antibody on cell

surface)

1 Antigen

molecules

2

First exposure

to antigen

Cell activation:

growth,division, and

differentiation

3

Antibody

molecules

Endoplasmic

reticulumFirst clone

Plasma (effector) cells secreting antibodies

4


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Primary immune

response

B cells with

different

antigen

receptors

Antigen receptor

(antibody on cell

surface)

1 Antigen

molecules

2

First exposure

to antigen

Cell activation:

growth,division, and

differentiation

3

Antibody

molecules

Endoplasmic

reticulumFirst clone

Plasma (effector) cells secreting antibodies

4

Memory cells

5


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Second clone

Plasma (effector) cells secreting antibodies Memory cells

6

Antigenmolecules

Second exposure

to same antigen

Endoplasmicreticulum

AntibodymoleculesSecondaryimmune

response (Mayoccur long afterprimary immuneresponse.)


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Time (days)

Second exposureto antigen X,

first exposure

to antigen Y

First exposureto antigen X

Secondary immuneresponse to

antigen X

Primary immuneresponse to

antigen Y

Primary immuneresponse to

antigen X

Antibodiesto X

Antibodiesto Y

5649423528211470

24 8 Antibodies are the weapons of the humoral


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24.8 Antibodies are the weapons of the humoralimmune response

Antibodies Are secreted by plasma (effector) B cells

Into the blood and lymph


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24 8 Antibodies are the weapons of the humoral


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24.8 Antibodies are the weapons of the humoralimmune response

An antibody molecule Is Y-shaped

With two antigen-binding sites

Specific to the antigenic determinants

That elicited its secretion

Antigen


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Antigen

Antigen-bindingsites

Lightchain

Heavychain

24 9 Antibodies mark antigens for elimination


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24.9 Antibodies mark antigens for elimination

Antibodies promote antigen elimination throughseveral mechanisms

Mark invaders

Which triggers mechanisms to neutralize or destroyinvaders

Animation: Antibodies
http://localhost/var/www/apps/conversion/tmp/scratch_5/24_09Antibodies_A.html


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Binding of antibodies to antigensinactivates antigens by

Neutralization

Agglutination

of microbes

Precipitation of

dissolved antigens

Phagocytosis Cell lysis

Activation of

complement system

Leads to

Foreign cell Hole

ComplementmoleculeBacteria

Antigen

molecules

Enhances

Bacterium

Virus

Macrophage

24 10 CONNECTION: Monoclonal antibodies are


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24.10 CONNECTION: Monoclonal antibodies arepowerful tools in the lab and clinic

Monoclonal antibodies (mAb) Name means all antibody-producing cells come from

one cell

Produced by fusing

B cells specific for a single antigenic determinant with Easy to grow tumor cells

Early pregnancy

(HCG in blood and urine)1st band


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Urine applied

to strip

(HCG in blood and urine)

HCG/mAbcomplex

ControlmAb

HCG HCG

HCG

3rd band

2nd band

24 10 CONNECTION: Monoclonal antibodies are


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24.10 CONNECTION: Monoclonal antibodies arepowerful tools in the lab and clinic

Monoclonal antibodies are useful in Research

Diagnosis

Treatment of certain cancers

24 11 Helper T cells stimulate the humoral and


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24.11 Helper T cells stimulate the humoral andcell-mediated immune responses

Helper T cells and cytotoxic T cells Are primarily responsible for the cell-mediated immune

response

Helper T cells also stimulate the humoral response


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24 11 Helper T cells stimulate the humoral and


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24.11 Helper T cells stimulate the humoral andcell-mediated immune responses

The helper T cells receptors Recognize the selfnonself complexes

The interaction activates the helper T cells

The helper T cell can then activate

Cytotoxic T cells and

B cells

Animation: Helper T Cell

Video: T Cell Receptors
http://localhost/var/www/apps/conversion/tmp/scratch_5/24_11TCellReceptors_SV.mpghttp://localhost/var/www/apps/conversion/tmp/scratch_5/24_11HelperTCells_A.html


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Microbe Macrophage

Self protein

Self-nonselfcomplex

T cellreceptor

Interleukin-2stimulatescell division

Interleukin-1stimulateshelper T cell

Bindingsite forantigen

Bindingsite forself protein

HelperT cell

Antigen-presenting

cellAntigen from microbe(nonself molecule)

1 2

3

4

5 6

7

B cell

CytotoxicT cell

Cell-mediatedimmuneresponse(attack oninfected cells)

Interleukin-2activates B cellsand other T cells

Humoralimmuneresponse(secretion ofantibodies byplasma cells)


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Microbe Macrophage

Self protein

Antigen from microbe

(nonself molecule)

1


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Self-nonselfcomplex

T cellreceptor

Interleukin-2stimulatescell division

Interleukin-1stimulateshelper T cell

Bindingsite forantigen

Bindingsite forself protein

HelperT cell

Antigen-presentingcell

23

4

5 6

7

B cell

CytotoxicT cell

Cell-mediatedimmune

response(attack oninfected cells)

Interleukin-2activates B cellsand other T cells

Humoral

immuneresponse(secretion ofantibodies byplasma cells)

24.12 Cytotoxic T cells destroy infected body cells


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24.12 Cytotoxic T cells destroy infected body cells

Cytotoxic T cells Are the only T cells that kill infected cells

Cytotoxic T cells

Bind to infected body cells

Destroy them

Animation: Cytotoxic T Cells
http://localhost/var/www/apps/conversion/tmp/scratch_5/24_12CytotoxicTCells_A.html


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1 Cytotoxic T cell bindsto infected cell

Self-nonselfcomplex

CytotoxicT cell

Foreignantigen

Perforinmolecule

Infected cell


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Self-nonselfcomplex

CytotoxicT cell

Foreignantigen

Perforinmolecule

Infected cell

Perforin makes holes ininfected cells membrane

and enzyme enters

Enzyme thatcan promoteapoptosis

Holeforming

2


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Self-nonselfcomplex

CytotoxicT cell

Foreignantigen

Perforinmolecule

Infected cell

Perforin makes holes ininfected cells membrane

and enzyme enters

Enzyme thatcan promoteapoptosis

Holeforming

2 Infected cellis destroyed

3

24.13 CONNECTION: HIV destroys helper T


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24.13 CONNECTION: HIV destroys helper Tcells, compromising the bodys defenses

AIDS (acquired immunodeficiency syndrome) Results from infection by HIV(human

immunodeficiency virus)

Between 1981 and 2007 AIDS killed more than 27million people

In 2006, 4.3 million people were newly infected withHIV, including 400,000 children under age 15

Most AIDS deaths occur in nonindustrialized nations

In some African nations, about 40% of adults are HIVpositive



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. 3 CONN C ON: V dest oys e pecells, compromising the bodys defenses

The AIDS virus usually attacks helper T cellsimpairing the

Cell-mediated immune response and

Humoral immune response Opening the way for opportunistic infection



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y pcells, compromising the bodys defenses

AIDS patients typically die from Opportunistic infections and

Cancers

That would normally be resisted by a person with ahealthy immune system

Animation: HIV Reproductive Cycle
http://localhost/var/www/apps/conversion/tmp/scratch_5/24_13HIVReproCycle_A.html


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24.14 EVOLUTION CONNECTION: The rapid


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pevolution of HIV complicates AIDStreatment

HIV mutates faster than any pathogen everstudied

New strains may be resistant to AIDS drugs

Drug-resistant strains now infect new patients

24.14 EVOLUTION CONNECTION: The rapid


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pevolution of HIV complicates AIDStreatment

The evolution of the AIDS virus is the number oneobstacle to eradicating AIDS

Current drugs are unable to

Eliminate HIV from a patient

Cure AIDS

24.15 The immune system depends on our


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y pmolecular fingerprints

The immune system normally reacts

Only against nonself substances

Not against self

24.15 The immune system depends on our


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y pmolecular fingerprints

Transplanted organs

May be rejected

Because the transplanted cells lack the uniquefingerprint of the patients self proteins

Donors are used that most closely match thepatients tissues

Transplants between identical twins do not typicallyhave this problem


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DISORDERSOF THE IMMUNE SYSTEM

24.16 CONNECTION: Malfunction or failure of


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the immune system causes disease

In autoimmune diseases

The immune system turns against the bodys ownmolecules

Examples include

Lupus

Rheumatoid arthritis

Insulin-dependent diabetes mellitus

Multiple sclerosis

24.16 CONNECTION: Malfunction or failure of


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the immune system causes disease

In immunodeficiency diseases

Immune components are lacking

Recurrent infections are frequent

The immune system may be weakened by Physical stress

Emotional stress

Students are more likely to be sick during a week ofexams

24.17 CONNECTION: Allergies are overreactions


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gto certain environmental antigens

Allergies

Are hypersensitive (exaggerated) responses

To antigens (allergens) in our environment



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to certain environmental antigens

Allergic reactions typically occur

Very rapidly in response to

Tiny amounts of an allergen

Allergic reactions can occur in many parts of thebody

Nasal passages

Bronchi

Skin


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3

B cell

(plasma cell)

Mast

cell

Histamine

Antibodiesattach tomast cell

Antigenic determinant

B cells makeantibodies

Allergen (pollen grain)enters bloodstream

Sensitization: Initial exposure to allergen

Allergen binds toantibodies onmast cell

Histamine isreleased, causingallergy symptoms

Later exposure to same allergen

1 2 3 4 5


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B cell(plasma cell)

Mast

cell

Histamine

Antibodiesattach tomast cell

Antigenic determinant

B cells makeantibodies

Allergen (pollen grain)enters bloodstream

Sensitization: Initial exposure to allergen

1 2 3


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Allergen binds toantibodies onmast cell

Histamine isreleased, causingallergy symptoms

Later exposure to same allergen

4 5



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to certain environmental antigens

Antihistamines

Interfere with histamines action

Provide temporary relief

Often make people drowsy

Anaphylactic shock

Extreme life-threatening allergic reaction

Can be treated with injections of epinephrine

The humoral immune response


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The cell-mediated immune response

B cell

T cell

Infected

body cell

Self-nonself complex

Antigens in

body fluid

Antibodies

which bind tomakes

Bodys

defenses


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include

(b)(a)

is present found in

at birthvertebrates and

invertebrates

is present found in

vertebratesonly after

exposure

produced by

cells called

Lymphocytes

include

responsible for

(c) (d)

cell-mediated

immune response

include

stimulate

(f)

stimulate

cytotoxic

T cells(e)

secrete responsible for

humoral

immune response

Bodys


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defenses

include

(b)(a)

is present found in

at birthvertebrates and

invertebrates

is present found in

vertebratesonly after

exposure

produced by

cells called

Lymphocytes


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include

responsible for

(c) (d)

cell-mediated

immune response

include

stimulate

(f)

stimulate

cytotoxic

T cells(e)

secrete responsible for

humoral

immune response

Lymphocytes

You should now be able to


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1. Describe the causes, symptoms, and treatments formononucleosis

2. Describe the structure and functions of thelymphatic system

3. Describe the specific nature of an immune systemresponse

4. Define antigen, antibody, passive immunity, andactive immunity



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5. Distinguish between the humoral immune responseand the cell-mediated immune response

6. Explain how an antigen and antibody interact

7. Compare a primary immune response to asecondary immune response

8. Relate the structure of an antibody to its functions

9. Describe the production of and uses for monoclonalantibodies



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10. Describe the specific functions of helper T cellsand cytotoxic T cells

11. Explain how HIV infects cells, multiplies, andcauses disease

12. Explain the causes of immunodeficiency diseasesand allergies

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