Download The Immune System

The Immune System
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I. Source of Infection
• Pathogen - microorganism that causes
disease
Ex: bacteria, virus, yeast, fungus,
protists, parasitic worms, etc.
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SOURCE
Direct
human
contact
Objects
(vectors)
Airborne
Water
Food
Arthropod
bites
EXAMPLES
HOW
SPREAD
PREVENTION
II. Non-Specific Defenses
(Innate Immunity)
A. Physical Defenses
1. First line of defense = skin, an
impermeable barrier that keeps
pathogens out
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II. Non-Specific Defenses
2. Defenses that protect natural body openings:
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mucus - traps microbes & prevents tissues
from drying out
saliva - wash surface of teeth; contain
lysozymes, enzymes which break
down bacteria
tears - lubricate surface of eyes & contains
lysozyme
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II. Non-Specific Defenses
B. Chemical defenses
1. Stomach acid: destroys many
swallowed pathogens
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2. Complement: group of blood
proteins that attach to
pathogens & help destroy
them
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II. Non-Specific Defenses
B. Chemical defenses
3. Phagocytes: white blood cells
that ingest & destroy
pathogens
(“pac-man” cells)
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4. Interferon: a protein substance that
interferes with viral
replication
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II. Non-Specific Defenses
5. Inflammation: damaged cells
release histamine, which dilates
blood vessels & increases tissue
fluid in the injured area (swelling);
this attracts phagocytes which
release proteins that increase
body temperature (fever) in order
to inhibit the growth of pathogens
& speed up the rate of tissue
repair
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III. Specific Defenses Against
Disease
• Immunity - resistance to a specific
pathogen or substance
• Antigen - a substance capable of
stimulating a specific immune
response - recognized as
“foreign” by the body
III. Specific Defenses Against
Disease
• Antibody - a protein produced in
response to a particular
antigen that will target &
destroy only that particular
antigen (foreign substance)
III. Specific Defenses Against
Disease
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III. Specific Defenses Against
Disease
• Types of Lymphocytes (White Blood Cells
that help defend the body)
A. Helper T cells: lymphocytes
processed in the thymus that
identify the invading antigen
& signal the immune system
to activate B cells = “guard cells”
*type of cell targeted by the HIV virus*
III. Specific Defenses Against
Disease
B. Killer T cells: lymphocytes processed
in the thymus that
produce powerful
chemicals that destroy
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“bomber cells”
III. Specific Defenses Against
Disease
C. B Cells: lymphocytes produced in the
bone marrow that make
antibodies
III. Specific Defenses Against
Disease
D. Memory Cells: cells that are made
during an immune
response but are kept
in storage for a future
attack by the same
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antigen - these cells
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contain the “recipe” for
making a specific type
of antibody
Passive vs. Active Immunity
Passive Immunity
• Develops when antibodies are received
(given to you)
• Natural: from mother through placenta
or breast milk
• Artificial: injection of gamma globulins
ex: anti-venom (antibodies)
• Temporary: lasts for a few weeks
• Fast: works almost immediately
Passive vs. Active Immunity
Active Immunity
• Develops when antibodies are made in
your own body
• Natural: pathogen (germ) exposure
• Artificial: vaccine
• Long lasting: months - years or permanent
• Slow: takes several weeks to develop & may
require a booster to form enough
memory cells
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End.