Transcript Immunity Power Point

Immunity
Defenses Against Disease
Lymph nodes
makes
lymphocytes.
Cilia in
respiratory tract
sweep away
debris.
Skin acts
as a
barrier.
White blood cells
engulf
microorganisms.
Spleen
filters out
bacteria.
Stomach
acid kills
bacteria.
Immunity
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The ability of the body
to resist disease.
First studied by
Edward Jenner in
1776.
He found that he
could use fluid from a
cowpox sore to
vaccinate against
smallpox (often fatal).
How Immunity Works
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The body is able to
tell the difference
between “self “(its
own cells and
molecules) and “
nonself “ (foreign cells
and molecules).
How Immunity Works
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The reaction of the
body to “nonself” cells
is called the immune
response.
This involves
destroying or
neutralizing foreign
cells or molecules
with white blood cells
and lymphatic tissue.
The Immune Response
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Antigens cause the
immune response to
happen.
Most antigens are
proteins, but some
are carbohydrates
and nucleic acids.
Most microorganisms
and toxins contain
antigens.
The Immune Response
Recognition and
destruction of foreign
antigens is the job of
the lymphocytes.
 Lymphocytes are
made in the bone
marrow of the
embryo and are
stored in lymphoid
tissue.
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Two Types of Lymphocytes (B &
T)
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Each lymphocyte has
receptors for only one
antigen.
When the receptors
recognize the
antigen, the
lymphocytes become
activated.
Activation of B Lymphocytes
(BLs)
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When BLs are
activated, they
enlarge and divide
repeatedly to form
two different cell
types:
1. Plasma Cells
2. Memory Cells
1. Plasma Cells
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Plasma cells secrete
antibodies, which are
proteins that react
specifically with
antigens and
inactivate them.
Antibodies have
active sites that fit a
compatible site on a
certain antigen.
Antigen-Antibody Reactions
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antigens
antibodies
There are many
different types of
antibodies and they
inactivate antigens in
five different ways.
Antigen-Antibody Reactions
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1. Agglutination:
Antigens are clumped
together and thus
inactivated.
2. Precipitation:
Antibodies form a
complex with the
antigens, and the
complex settles out.
Antigen-Antibody Reactions
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3. Neutralization:
Antibodies combine
with antigens,
inactivating the toxic
site of the antigen
molecule.
Antigen-Antibody Reactions
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4. Lysis: Antibodies
cause the cell
membranes of the
antigenic
microorganisms to
burst.
Antigen-Antibody Reactions
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5. Complement
System: The
complement system
is a group of enzymes
in the plasma. The
antigen-antibody
complex activates
these enzymes,
which attack the
antigenic material.
2. Memory Cells
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The memory cells
stay in the lymphoid
tissue.
If the same antigen
enters the body, the
memory cells will
immediately produce
antibodies against it.
Activation of T Lymphocytes (TLs)
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When TLs contact an
antigen, they divide rapidly
and make more TLS.Some
stay in the lymphoid tissue
as memory cells.
Other TLs pass into the
circulatory system and
body tissues, where they
combine with the antigens
and destroy them.
How Lymphocytes Make
Antibodies
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Click here for animation.
Types of Immunity
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Three main types of
immunity:
1. Inborn Immunity
2. Acquired Immunity
3. Passive Immunity
1. Inborn Immunity
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Does not involve antibodies.
Present in all humans from
birth.
Prevents humans from
becoming infected with certain
types of bacteria and viruses.
Ex. Feline leukemia affects
cats not humans.
2. Acquired Immunity
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Two ways to get it:
1. Contracting a diseaseEx. Chicken pox. Memory
cells will,stay in the body
and produce antibodies.
2. Vaccination-Vaccine
serves to stimulate the
production of specific
antibodies to certain
antigens.
3. Passive Immunity
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Does not last long (about
one month).
Body destroys the
“borrowed” antibodies.
Fast acting.
Found in babies who get
antibodies via mother’s milk.
Helps protect child for a few
months.