Ch51Immunity - Environmental
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Transcript Ch51Immunity - Environmental
phagocytic
leukocyte
“Fighting the
Enemy Within”
Immune System
Chapter 51
AP Biology
lymphocytes
attacking
cancer cell
lymph
system
2006-2007
Avenues of attack
Points of entry
digestive system
respiratory system
urogenital tract
break in skin
Routes of attack
circulatory system
lymph system
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Why an immune system?
Attack from outside
lots of organisms want you for lunch!
animals must defend themselves against
unwelcome invaders
viruses
bacteria
All in a
good day’s
work!
protists
fungi
we are a tasty vitamin-packed meal
cells are packages of macromolecules
no cell wall
traded mobility for susceptibility
Attack from inside
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defend against abnormal body cells = cancers
Lines of defense
1st line: Barriers
broad, external defense
“walls & moats”
skin & mucus membranes
2nd line: Non-specific patrol
broad, internal defense
“patrolling soldiers”
leukocytes (phagocytic WBCs)
3rd line: Immune system
specific, acquired immunity
“elite trained units”
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lymphocytes & antibodies
1st: External defense
non-specific defense
external barrier
epithelial cells &
mucus membranes
skin
respiratory system
digestive system
genito-urinary tract
Lining of trachea:
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ciliated cells & mucus
secreting cells
1st: Chemical barriers on epithelium
Skin & mucous membrane secretions
sweat
pH 3-5
tears
washing action
mucus
traps microbes
saliva
anti-bacterial = “lick your wounds”
stomach acid
pH 2
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anti-microbial proteins
lysozyme
digests bacterial cell walls
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
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Leukocytes: Phagocytic WBCs
Neutrophils
attracted by chemical signals released
by damaged cells
enter infected tissue, engulf & ingest
microbes
amoeba-like (fierce!)
digest via lysosomes
~3 day life span
Macrophages
“big eater”
bigger, long-lived
phagocytes
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Phagocytes
macrophage
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yeast
Lymph system
Production & transport of leukocytes
Traps foreign invaders
lymph vessels
(intertwined amongst blood vessels)
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lymph node
Development of Red & White blood cells
inflammatory
response
Red blood cells
fight
parasites
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develop into
macrophages
short-lived phagocytes
60-70% WBC
Inflammatory response
Damage to tissue triggers
local inflammatory
response
release histamines &
prostaglandins
capillaries dilate,
more permeable
increase blood supply
delivers WBC, RBC, platelets,
clotting factors
lead to clot formation
swelling, redness & heat of
inflammation & infection
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Inflammatory response
Reaction to tissue damage
Pin or splinter
Blood clot
swelling
Bacteria
Chemical
alarm signals
Phagocytes
Blood vessel
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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
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of iron to grow
3rd: Acquired Immunity
Specific defense
lymphocytes
B lymphocytes (B cells)
T lymphocytes (T cells)
antibodies
immunoglobulins
Responds to…
antigens
specific microorganisms
specific toxins
abnormal body cells
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Antigens
Proteins that serve as cellular name tags
foreign antigens cause response from WBCs
proteins belonging to:
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
“self”
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“foreign”
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
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B cells
Humoral response = “in fluid”
defense against attackers circulating freely
in blood & lymph
Specific response
produces antibodies against
specific antigen
tagging protein = immunogloblin
millions of different B cells,
each produces different antibodies,
each recognizes a different antigen
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types of B cells
plasma cells
immediate production of antibodies
short term release
memory cells
long term immunity
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“this is foreign!”
variable
binding region
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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
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Proteins that bind to a specific antigen
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Antibodies
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each B cell
has ~100,000
antigen receptors
How antibodies work
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10 to 17 days for full response
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release antibodies
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plasma cells
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recognition
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captured
invaders
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memory cells
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B cells + antibodies
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tested by
B cells
(in blood & lymph)
invader
(foreign antigen)
“reserves”
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B cell immune response
clone
1000s of clone cells
1° vs 2° response to disease
Memory B cells allow a rapid, amplified
response with future exposure to pathogen
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How can we
have so many
antibody
proteins &
so few genes?
Variable region
Antibody
Constant region
Light chain
B cell
Heavy chain
Variable DNA
combinations:
Transcription
of gene
• 1M different B cells
• 10M different T cells
mRNA
DNA of
differentiated
B cell
C
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Rearrangement
of DNA
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40 genes for
Variable region
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Chromosome
of undifferentiated B cell
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
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1914 – 1995
Jonas Salk
Developed first vaccine
against polio
April 12, 1955
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Polio epidemics
1994:
Americas polio free
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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
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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
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killer T cells
attack infected body cells
How are cells tagged with antigens
Glycoproteins on surface of cells have
unique “fingerprint”
major histocompatibility proteins (MHC)
MHC proteins constantly export bits of
cellular protein to cell surface
“snapshot” of what is
going on inside cell
T cell
MHC proteins
displaying self-antigens
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How do T cells know a cell is infected
Infected cells digest some pathogens &
export pieces to MHC proteins on cell
surface
invading
pathogen
antigen presenting cells (APC)
MHC proteins
displaying
foreign antigens
T cell
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T cell antigen
receptors
T cell response
infected cell
helper
T cell
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helper
T cell
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stimulate
B cells &
antibodies
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activated
macrophage
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or
helper
T cell
helper
T cell
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interleukin 1
activate
killer T cells
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helper
T cell
killer
T cell
Attack of the Killer T cells
Destroys infected body cells
binds to target cell
secretes perforin protein
punctures cell membrane of infected cell
Killer T cell
Killer T cell
binds to
infected
cell
Vesicle
Cell
membrane
Perforin
punctures
cell membrane
Cell
membrane
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Infected cell
destroyed
Target cell
Immune response
pathogen invasion
antigen
exposure
free antigens in blood
humoral response
macrophages
cellular response
B cells
helper
T cells
T cells
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Y antibodies
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memory
B cells
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plasma
B cells
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antigens on infected cells
memory
T cells
cytotoxic
T cells
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 -IgE
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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
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Any Questions??
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2006-2007