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The Immune System
Chapter 43
Nonspecific Immunity
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Helps prevent the entry of microbes:
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Skin and mucus membranes – 1st line of defense
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Helps prevent the spread of microbes:
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Acidify the skin
Saliva, tears – have antimicrobial proteins
Nostril hairs & mucus
Stomach acids
Phagocytes – destroy themselves and pathogen
Inflammatory response – brings blood and therefore
more phagocytes to the area
Antimicrobial proteins – either directly attack
microbes or interfere with their reproduction
Specific Immunity
 The
body responds to a particular type of
infectious agent
 Four components:
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Specificity
Diversity
Memory
Self/non-self recognition
 Lymphocytes
provide the specificity of
the immune system
Specificity
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The immune system is able to recognize and
eliminate particular microorganisms and foreign
molecules
 This is the job of the lymphocytes
 Antigen – a foreign substance that elicits a
specific response by lymphocytes
 Antibody – an antigen-binding protein produced
by lymphocytes that functions as the effector in
an immune response; these tag the invading cell
for destruction
Diversity
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The ability to respond to the wide variety of
antigens which enter the body is based on the
diversity of antigen-specific lymphocytes present
in the system
 The primary immune response is the making
of lymphocytes during the 1st exposure to the
antigen
 A secondary immune response occurs when
the body is exposed to the antigen again
Memory
 The
ability to recognize a previously
encountered antigen
 This is based on memory cells which are
produced during the primary immune
response
 Memory cells are not active during the
primary response but survive in the
system for a long time
 This is acquired immunity
Self/non-self recognition
 The
immune system is able to distinguish
between the body’s own molecules and
foreign antigens
 It develops before birth when the
lymphocytes begin to mature
 The failure of this ability to recognize self
leads to autoimmune disorders that
destroy the body’s own tissues
Blood groups and transfusion
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An example of self/non-self recognition
Type A blood – produces A antigen; makes B
antibodies
Type B blood – produces B antigen; makes A
antibodies
Type AB blood – produces A and B antigen;
makes neither A nor B antibodies
Type O blood – produces neither A nor B
antigen; makes both A and B antibodies
Universal donor – Type O: no antigens
Universal recipients – Type AB: no antibodies
Immune Response: either humoral
or cell-mediated
immunity – antibodies produced
in response to toxins, bacteria, and viruses
present in the body fluids (the ‘humors’)
 Cell-mediated immunity – the response
to intracellular bacteria, viruses, fungi,
protozoa, worms, transplanted tissues,
and cancer cells
 Humoral
Achieving Immunity
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Active immunity – conferred by recovery from
an infectious disease
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Depends on response by the person’s own immune
system
May be acquired through illness or vaccination
Passive immunity – transferred from one
person to another
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Pregnant or nursing mother to child
Artificially from an animal or another person already
immune to the disease
Abnormal immune function
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Allergies – a hypersensitivity to an environmental
antigen
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Autoimmune disorders – an immune system reaction
against self
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Anaphylactic shock – a life-threatening condition associated with
some allergens such as insect stings or peanuts; epinephrine
may be used as an anecdote
lupus erythematous, rheumatoid arthritis, multiple sclerosis,
insulin-dependent (‘juvenile’) diabetes -?
Immunodeficiency diseases – immune system is not
working
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Hodgkin’s disease
AIDS