Download Immune System-nonspecific defenses

Biotechnology I
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Your body is attacked by microorganisms 24
hours, 7 days a week. Microorganisms are
looking to find shelter and nutrients to
sustain their life and reproduce.
Given this, why are you not constantly sick?
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What distinguishes non-specific immunity
from specific-immunity
When does humoral immunity, cell-specific
immunity come into play when defending
against invading pathogens?
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Definition
 Ability of an organism to make chemicals and
specific cells that protect the organism from
foreign invaders
 Analogous to your own Navy Seal Team
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Definition
 Organism’s ability to defend itself from invading
microorganisms
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Two types
 Non-specific
▪ First and second-line of
defense
▪ Prevents pathogens from
invading the body
▪ Treats all invading
pathogens the same
▪ Most animals have this form
of immunity
 Specific
▪ Third line of defense
▪ Activated after pathogen
enters the body
▪ Defense response specific to
invading organism
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Immune system must distinguish
between self and non-self
 Self – any component that belongs to
the organism
 Non-Self- anything that doesn’t belong
to the organism
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Comes into play when non-specific defense
mechanisms fail to ward off infectious agent
Specific defense mechanisms activated with
presence of foreign invader
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Four key features
 Specific- responds to pathogens actually
present
 Diverse – can respond to wide variety of
pathogens
 Distinguishes self from non-self- prevents
destroying self cells
 Immunological memory- effectiveness
improves with later exposures
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Development of resistance
to specific invaders
Development of immunity
occur in two ways:
 Natural infection –
infected with virus or
bacteria
 Vaccination - injected
with inactive form of the
microorganism
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Humoral Immunity
 White blood cells involved – B-lymphocytes (B
cells)
▪ Involved in producing antibodies
 Attack pathogens floating around in body fluids
Cell-mediated Immunity
 White blood cells involved – T-lymphocytes (T
cells)
 Attack cells infected with pathogen
A molecule that is recognized by the body as nonself
 Possesses three characteristics
 High molecular weight- large molecule
 Chemically complex –typically proteins and
polysaccharides
 Foreignness (recognized as non-self)
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Antigen stimulate the
production of an
antibody
Antibody is a protein in
the blood plasma that
attaches to the antigen
and counters its effects
Antibody-antigen
complex –insoluble
 Ingested and
destroyed by
macrophages
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Involves B-lymphocytes
Antibodies produced by B-lymphocytes are
carried to infection site
Antibodies bind to foreign antigen and
neutralize their effect by having the
antibody-antigen complex broken down
Speculate why keeping our environment too
clean would be bad for our immune system
 Which immune system would most benefit –
non-specific or specific immunity? Why?
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PROPERTY OF PIMA COUNTY JTED, 2010
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Takes two exposures to trigger the strongest
defense
 Primary immune response- first exposure to antigen;
▪ triggers formation of effector cells and memory cells
▪ Antibodies produced by effector cells appear in the blood
▪ peaks about two weeks after initial exposure
 Secondary immune response –second exposure to the
antigen
▪ triggers a faster and stronger response have higher levels of
antibodies
▪ response lasts longer
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Each exposure to antigen triggers formation of two
cells
 B cells – survive only a few days; produce antibodies
 Memory cells- last a long time; e.g. decades
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Memory cells initiate the secondary immune
response
 Multiply quickly producing a new clone of B cells;
▪ these B cells produce the antibodies
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What do you think the purpose
of booster shots when you got
vaccinated for childhood
diseases like measles, mumps,
whooping cough?
PROPERTY OF PIMA COUNTY JTED, 2010
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