Download 14 Lab Biology - Immunity.ppt

Infectious Disease
and the Immune
System
KOCH’S Postulates
1. Pathogen must occur in
body of organism with
the disease.
2. Pathogen should be
isolated and grown in
culture.
3. Inoculated animal should
develop the disease.
4. Same pathogen should be
grown in culture.
Modern Biology
Pages 954-958
Viruses
• Viruses are nonliving.
• Only characteristic
of living organisms
is ability to
reproduce.
Modern Biology
Pages 486-490
Viruses
• Viruses are
composed of;
– a protein
– DNA or RNA
molecule.
Modern Biology
Pages 486-490
Viruses
• Viruses are composed
of;
– a protein called a
capsid.
– DNA or RNA
molecule.
– Some viruses have a
membrane like
structure called a
envelope.
Modern Biology
Pages 486-490
Viruses
• Virus types:
– DNA viruses.
– RNA viruses.
Modern Biology
Pages 486-490
Viruses
• Retroviruses
– RNA core.
– Must contain an
enzyme called
reverse
transcriptase.
– RNA --DNA-mRNA--Protein.
Modern Biology
Pages 486-490
Plasma Membrane
• Contains
– Transmembrane
proteins.
• Channels
• Carriers
– Surface proteins.
• Glycoproteins.
– Cholesterol
molecules
HIV & Plasma
Membrane
• HIV recognizes CD4 (part
of T lymphocytes) protein
on cell surface.
• Gains entry & creates DNA
molecule.
• DNA becomes part of cell’s
DNA.
• Makes more viruses.
Glycoprotein
Viroids & Prions
• Viroids:
– Naked RNA that
can replicate.
• Prions:
– Infectious
proteins.
– Disrupt the cells
activities.
Modern Biology
Pages 486-490
Polio virus
Influenza Virus
Ebola
Rabies
Bacteria
• Prokaryotic cells.
• Always single
cell.
• Composed of:
– Cell wall
– Cell membrane
– Cytoplasm.
Modern Biology
Pages 474-477
Bacteria
• Some bacteria have
a capsule.
– Composed of
polysaccharides.
– Protects bacteria
from WBCs.
• Bacteria have short
hair like structures
called pili.
Modern Biology
Pages 474-477
Infectious Disease
and the Immune
System
What is a pathogen?
• A pathogen is
anything that
causes disease.
–
–
–
–
–
–
Bacteria
Protist
Virus
Retro-virus
Fungus
prion
Modern Biology
Pages 956-957
How does the body
recognize pathogens?
• Most pathogens
have proteins.
– Called antigens.
– Body’s cells have
MHCs
– “Act as off campus
I.D. cards”.
– Wrong MHC –
engulf and destroy!
Modern Biology
Pages 956-957
What are nonspecific
defenses?
• Resistance is your
bodies ability to
defend against
pathogens.
• Your immune system
gives you resistance.
Modern Biology
Pages 954-958
What are physical
barriers to disease?
• Nonspecific defense.
– Sweat, oils, & waxes.
– Mucous membranes.
– HCL of stomach.
Modern Biology
Pages 954-958
Why do you
get a fever?
•
•
•
Pathogens that attack
human body like 98.6 F.
best.
Raising temperature of
body increases
effectiveness of WBC’s.
Decreases effectiveness
of pathogen.
Modern Biology
Pages 954-958
Interferon
•
•
Chemical released by
cells infected by viruses.
Causes surrounding cells
to resist infection.
Modern Biology
Pages 954-958
Inflammatory
Response
• Inflammatory
response
occurs when
pathogen
penetrates
the skin.
Modern Biology
Pages 954-958
Inflammatory
Response
• Symptoms:
– Redness
– Heat
– Swelling
pain
Pages 954-958
Inflammatory
Response
• What occurs:
– Damaged cells
release
histamines.
– Causes
vasodialation
– Causes increase
in permeability.
Pages 954-958
Non specific
Cellular Defense
• Neutrophils
–
–
–
–
–
Most common
Kill pathogens using
phagocytosis.
Circulate in blood
stream.
Migrate towards site
of infection.
(chemotaxis)
Move out of the
blood stream
(emmigration)
Pages 954-958
Non specific
Cellular Defense
• Macrophages
– Stationed in
certain tissues.
– Destroy by
phagocytosis.
– Rid the body of
debris and
damaged cells.
Wednesday 5/21/2003
Pages 954-958
Non specific
Cellular Defense
•
Natural Killer Cells
– Attack cells
which have been
infected by
pathogen.
– Kills cancer cells.
– Kills by
puncturing cell
membrane.
Wednesday 5/21/2003
Pages 954-958
Wednesday 5/21/2003
Pages 954-958
How WBCs
Recognize Pathogens
•
•
•
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All of your cells are marked
as “self” by proteins.
(MHCs)
Nonspecific WBCs recognize
your proteins.
They leave these cells alone.
Any cell that does not have
MHCs is attacked.
Pages 954-958
Summary of Immune System
To Date:
• Body has different “lines of defense”.
– Barriers
• Skin, mucous membranes, secretions.
– Non specific defenses.
• Macrophages, neutrophils, natural killer cells.
• Interferon, compliment.
– Specific defenses.
Specific Defenses
Pages 959-964
• If pathogens
enter the body
the immune
system responds.
• Response is to
specific
pathogens.
(Single type)
RBC of different blood type has
antigens
Immune System
Organs
•
•
•
•
•
•
Thymus gland
Spleen
Bone marrow
Lymph nodes
B cells
T cells.
Pages 959-964
How Antigens are
Recognized
•
•
•
Pathogen has proteins
(antigens) on its
surface.
Macrophages destroy
pathogen.
Macrophages present
parts of the pathogen
(antigen) to the
lymphocytes.
Pages 959-964
How Antigens are
Recognized
• Lymphocytes then
remember the
antigen.
• Attack and
destroy if in body.
• Cell mediated
immune response.
Pages 959-964
Cell Mediated
Immune System
• T cells directly
attack and
destroy antigen.
• B cells produce
antibodies that
recognize
antigen.
Bacteria adhering to
T lymphocyte.
Pages 959-964
Antibody Mediated
Immune System
•
Macrophages present
portion of pathogen
to B Lymphocytes.
•
Lymphocytes learn
pathogen structure
and divide into
plasma cells.
Pages 962-965
Antibody Mediated
Immune System
•
Plasma cells produce
proteins called
antibodies.
•
Antibodies recognize
and attach to
pathogen.
•
Antibodies are Yshaped proteins.
Pages 962-965
Antibody Mediated
Immune System
•
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•
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The two arms of the
antibody are identical,
but ends are different.
Antibodies match
proteins of pathogen.
Actions of antibodies.
Pages 962-965
Antibody Mediated
Immune System
•
Primary response occurs
the first time exposure
to pathogen occurs.
•
Secondary response
occurs when pathogen
invades again.
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–
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Faster reaction.
Stronger reaction.
Memory B cells.
Pages 962-965
Immunity &
Vaccination
•
Naturally acquired active immunity.
•
Naturally acquired passive immunity.
•
Artificially acquired active immunity.
•
Artificially acquired passive immunity.
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Your are exposed to pathogen in everyday life.
Breast milk.
Mom’s antibodies prior to to birth.
Vaccination.
You are given a shot of antibodies.
Pages 962-965