IMMUNE SYSTEM
BENCHMARK STUDY GUIDE
What is a PATHOGEN?
Anything that causes disease
 Can be a bacteria, virus, fungi,
parasites
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 Bacteria
produce toxins
 Viruses lyse cells
What is a VIRUS?
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A non-living particle that requires a host to
replicate
Can cause disease
Found in soil, water, air, surfaces
What happens during the LYTIC
CYCLE?
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Attachment
Entry
DNA Replication and Virus Protein Production
Assembly
Lysis
What happens during the LYSOGENIC
CYCLE?
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Attachment
Entry
Provirus – Viral DNA is incorporated into host DNA
Cell DNA with virus DNA is replicated
What adaptations allow bacteria to
survive in different environments?
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Cell Walls
Can withstand harsh environments
Endospores
Aerobic or anaerobic respiration
What are some useful uses for
bacteria?
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Make cheese and yogurt
Clean spills
Make antibiotics
Nitrogen fixation
Recycle nutrients/decomposers
Describe how Robert Koch explained
the cause of disease. Steps?
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Pathogen is isolated from a host
Pathogen is grown/cultured
Pathogen is introduced to another host
New host becomes ill, must have same
symptoms
Pathogen is isolated – must be same pathogen as
original
What are the causes of…

Malaria – plasmodium parasite on mosquitoes
 Mosquito

HIV – Virus
 Passed

is a vector
through exchange of body fluids
Shingles – Virus
 Passed
on by contact/droplets
Define INNATE IMMUNITY

First line of defense
 Barriers
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and Mucus
Non-specific defense
Skin
Mucus membranes
Tears and Saliva
 Lysozyme
enzyme – breaks down bacterial cell walls
and membranes
What is INFLAMMATION?
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Non-specific defense
2nd Line of Defense
 Entry
of pathogen
 Mast cells release histamine
 Histamine
triggers – pain, heat, swelling, redness
 Dilate red blood vessels to allow phagocytes to damage
site
 Phagocytes
(macrophages, monocytes, neutrophils)
digest pathogens
 Pus
How does the body react to viral
infections?
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Virus infected cells release INTERFERONS
Interferons (chemicals) tell neighboring cells to
make antiviral proteins
 Viruses
cannot enter neighboring cells
What is the function of white blood cells?
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Basophils – make histamine
Macrophage – digest invading cells
Describe 2 ways bacteria can reproduce?
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Binary fission
 Asexual
reproduction
 One bacteria replicates DNA and divides into two
cells

Conjugation
 Sexual
reproduction
 One bacteria passes on a plasmid or new DNA to
another bacteria through pili
What is ACQUIRED IMMUNITY?
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3rd Line of Defense
Build up resistance
Specific Immunity
Body uses T and B cells against a specific
pathogen
Cellular Immunity
Antibody Immunity
Cellular Immunity
1.
2.
3.
4.
5.
Pathogen is engulfed by macrophage
Macrophage presents digested pathogen to Helper T
Cell
Helper T cell activates Cytotoxic T cells
Cytotoxic T cells signal infected cells to commit
“suicide”
Memory Cytotoxic T cells are made
Antibody Immunity
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Pathogen (bacteria) is engulfed by macrophage
Macrophage presents digested bacteria to Helper T
cell
Helper T cell activates B cell
B cell turns into plasma cell
Plasma cell makes Antibodies
 Antibodies
circulate through blood stream to find and
collect bacteria
What is PASSIVE IMMUNITY?
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Receive Antibodies by injection or breast feeding
Passive – you DON’T make antibodies yourself
Temporary
What is ACTIVE IMMUNITY
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Occurs Naturally – You build up immune system
You have to get sick
Body makes memory B and T cells
What is an ANTIBIOTIC?
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Most come from penicillin
Target – bacterial infections
CANNOT be used on viruses
Break down the cell walls
What is RESISTANCE?
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When a bacteria is no longer sensitive to
antibiotics