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phagocytic leukocyte. Chapter 43. Immune System. lymphocytes attacking cancer cell. lymph system. Why an immune system?. Attack from outside animals must defend themselves against unwelcome invaders viruses protists bacteria fungi we are a tasty vitamin-packed meal - PowerPoint PPT Presentation
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2008-2009 AP Biology
Chapter 43.
Immune System
lymphocytesattackingcancer cell
phagocytic leukocyte
lymphsystem
2008-2009AP Biology
Why an immune system? Attack from outside
animals must defend themselves against unwelcome invaders viruses protists bacteria fungi
we are a tasty vitamin-packed meal cells are packages of macromolecules no cell wall
traded mobility for susceptibility
Attack from inside defend against abnormal body cells = cancers
2008-2009AP Biology
Lines of defense 1st line: Barriers
broad, innate, external defense “barbed wire”
skin & mucus membranes
2nd line: Non-specific patrol broad, innate, internal defense
“untrained soldiers” leukocytes (WBCs)
3rd line: Immune system specific, acquired immunity
“elite trained units” lymphocytes & antibodies
2008-2009AP Biology
1st: External defense non-specific defense external barrier
epithelial cells & mucus membranes skin respiratory system digestive system genito-urinary tract
Lining of trachea: ciliated cells & mucus secreting cells
2008-2009AP Biology
1st: Chemical barriers on epithelium Skin & mucous membrane secretions
sweat pH 3-5
tears washing action
mucus traps microbes
saliva anti-baterial = “lick your wounds”
stomach acid pH 2-3
anti-microbial proteins lysozyme
digests bacterial cell walls
2008-2009AP Biology
2nd: Internal, broad range patrol leukocytes innate defense
rapid response cells & proteins
attack invaders that penetrate body’s outer barriers leukocytes
phagocytic white blood cells anti-microbial proteins inflammatory response natural killer cells
2008-2009AP Biology
Leukocytes: Phagocytic WBCs Neutrophils
attracted by chemical signals released by damaged cells (interferon)
enter infected tissue, engulf & ingest microbes amoeba-like lysosomes ~3 day life span
Macrophages “big eater” bigger, long-lived
phagocytes
2008-2009AP Biology
Lymph systemProduction & transport of leukocytesTraps foreign invaders
lymph node
lymph vessels(intertwined amongst blood vessels)
2008-2009AP Biology
Development of Red & White blood cells
short-lived phagocytes60-70% WBC
develop into macrophages
inflammatory response
fightparasites
Red blood cells
2008-2009AP Biology
Inflammatory response
Bacteria
Blood vessel
Chemicalalarm signals
Pin or splinterBlood clot
Phagocytes
swelling
Reaction to tissue damage
2008-2009AP Biology
Inflammatory response Damage to tissue triggers
local inflammatory response histamines & prostaglandins
released capillaries dilate,
more permeable lead to clot formation
increased blood supply swelling, redness & heat of
inflammation & infection delivers WBC, RBC, platelets,
clotting factors
2008-2009AP Biology
Fever When a local response is not enough
systemic response to infection activated macrophages release interleukin-1
triggers hypothalamus in brain to readjust body thermostat to raise body temperature
higher temperature helps defense inhibits bacterial growth stimulates phagocytosis speeds up repair of tissues causes liver & spleen to store iron
reducing blood iron levels bacteria need large amounts
of iron to grow
2008-2009AP Biology
3rd: Acquired Immunity Specific defense
lymphocytes B lymphocytes (B cells) T lymphocytes (T cells)
antibodies immunoglobulins
Responds to… specific microorganisms specific toxins abnormal body cells antigens
2008-2009AP Biology“self” “foreign”
Antigens Proteins that serve as cellular name tags
foreign antigens cause response from WBCs proteins belonging:
viruses, bacteria, protozoa, parasitic worms, fungi, toxins non-pathogens: pollen & transplanted tissue
B cells & T cells respond to different antigens B cells recognize intact antigens
invaders in blood & lymph T cells recognize antigen fragments
invaders which have infected cells
2008-2009AP Biology
Lymphocytes B cells
mature in bone marrow humoral response system
“humors” = body fluids produce antibodies
T cells mature in thymus cellular response system
Learn to distinguish “self” from “non-self” antigens during maturation
2008-2009AP Biology
B cells Humoral response = “in fluid”
defense against attackers circulating freely in blood & lymph
Specific response recognizes specific antigen produces antibodies against it
tagging protein = immunogloblin millions of different B cells,
each produces different antibodies,each recognizes a different antigen
types of B cells plasma cells
immediate production of antibodies short term release
memory cells long term immunity
2008-2009AP Biology
Antibodies Proteins that bind to a specific antigen
multi-chain proteins produced by B cells antibodies match molecular shape of antigens immune system has antibodies to respond to
millions of antigens (invaders) tagging system
“this is foreign!”
each B cell has ~100,000
antigen receptors
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variable binding region
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2008-2009AP Biology
B cell immune responsetested by
B cells
10 to 17 days for full response
invader(foreign antigen) B cells + antibodies
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recognition
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clone1000s of clone cellsY
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plasma cellsrelease antibodies
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memory cells“reserves”
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Ycapturedinvaders
2008-2009AP Biology
1° vs 2° response to disease Memory B cells allow a rapid, amplified
response with future exposure to pathogen
2008-2009AP Biology
How can we have so many antibody proteins & so few genes?
Light chain
Constant region
Transcriptionof gene
mRNA
Chromosome of undifferentiated B cell
B cell
CC
DJ
DNA ofdifferentiatedB cell
Rearrangement of DNA
VTranslation of mRNA
Antibody
40 genes for Variable region
Variable region
Heavy chain
Variable DNA combinations:
• 1M different B cells• 10M different T cells
2008-2009AP Biology
Vaccinations Active immunity
immune system exposed to harmless version of pathogen
Stimulates immune system to produce antibodies to invader rapid response if
future exposure Most successful
against viral diseases
2008-2009AP Biology
Passive immunity Maternal immunity
antibodies pass from mother to baby across placenta or in breast milk
critical role of breastfeeding in infant health mother is creating antibodies against
pathogens baby is being exposed to Injection
injection of antibodies short-term immunity
2008-2009AP Biology
T cells Immune response to infected cells
defense against invaders inside infected cells viruses & bacteria within infected cells,
fungi, protozoa & parasitic worms defense against “non-self” cells
cancer & transplant cells Kinds of T cells
helper T cells stimulate immune system
killer T cells attack infected body cells
2008-2009AP Biology
How are cells tagged with antigens Glycoproteins on surface of cells have
unique “fingerprint” major histocompatibility proteins (MHC) human leukocyte antigens (HLA)
MHC proteins constantly export bits of cellular protein to cell surface “snapshot” of what is
going on inside cell
MHC proteinsdisplaying self-antigens
T cell
2008-2009AP Biology
How do T cells know a cell is infected Infected cells digest some pathogens &
export pieces to MHC proteins on cell surface antigen presenting cells (APC)
T cell
MHC proteinsdisplaying foreign antigens
invading pathogen
T cell antigen receptors
2008-2009AP Biology
T cell response
helperT cell
infected cell
activatedmacrophage
helperT cell
helperT cell
helperT cell
helperT cell stimulate
B cells &antibodies
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killerT cell
activatekiller T cells
orinterleukin 1
interleukin 2
interleukin 2
2008-2009AP Biology
Attack of the Killer T cells
Killer T cellbinds toinfected
cell
Destroys infected body cells binds to target cell secretes perforin protein
punctures cell membrane of infected cell
Infected celldestroyed
Perforin puncturescell membrane
Cell membrane
Killer T cell
Cell membrane
Target cell
Vesicle
2008-2009AP Biology
Immune responsepathogen invasion
antigenexposure
free antigens in blood antigens on infected cells
humoral response cellular response
B cells T cells
macrophages
helperT cells
plasmaB cells
memoryB cells
memoryT cells
cytotoxicT cells
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2008-2009AP Biology
HIV & AIDS Human Immunodeficiency Virus
virus infects helper T cells helper T cells don’t activate rest of
immune system: T cells & B cells also destroy T cells
Acquired ImmunoDeficiency Syndrome infections by opportunistic
diseases death usually from other
infections pneumonia or cancer
2008-2009AP Biology
Immune system malfunctions Auto-immune diseases
immune system attacks own molecules & cells lupus
antibodies against many molecules released by normal breakdown of cells
rheumatoid arthritis antibodies causing damage to cartilage & bone
diabetes beta-islet cells of pancreas attacked & destroyed
multiple sclerosis T cells attack myelin sheath of brain & spinal cord nerves
Allergies over-reaction to environmental antigens
allergens = proteins on pollen, from dust mites, in animal saliva
2008-2009AP Biology
Key attributes of immune system 4 attributes that characterize the
immune system as a whole specificity
antigen-antibody specificity diversity
react to millions of antigens memory
rapid 2° response ability to distinguish self vs. non-self
maturation & training process to reduce auto-immune disease