IMMUNITY

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IMMUNITY
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Chapter Outlines

• Define antibody, antigen, cell-mediated immune
  response and humoral immune response
• Describe lymph structure and its function
• Explain detail cell-mediated immune response and
  humoral immune response
• Explain self and non-self recognition , autoimun
  concept and its application in medicine
• Describe and explain AIDS, causative agent,
  symptoms, prevention, mechanism of HIV infection
  and replication of HIV.

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11.1 Immune response

• By the end of the lesson, students should be able
• to
• describe immunity
• describe the roles of lymphoid organs in immunity
• describe the structure of antibody and state the
  classes of antibodies

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Key terms

• Pathogens Disease-causing microorganism,
  including certain viruses, bacteria, fungi and
  protozoa
• Immune response recognition of foreign
  macromolecules and response aimed at eliminating
  them
• Antigen any molecule that can be specifically
  recognized as foreign by cell of the immune
  system
• Antibodies highly specific protein that
  recognized and bind to specific antigens

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An overview of the bodys defenses
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The Human Immune System

• Two types of defensive mechanism
• 1) Non-specific
• protection by skin, mucous and acidic at
  stomach
• 2) Specific
• a) Cell-mediated immune response
• b) Humoral immune response

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Immunity

• Organism defence system in response to foreign
  or potential dangerous substances (antigen)
• Type of immunity
• 1) Pasive immunity
• - induced by injection of serum taken from
  an individual already immune to particular
  antigen
• - transfer the maternal antibodies via placenta
  or breast milk.
• 2) Active immunity
• -arises when the body produces antibodies
  against an invading foreign substances

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• Immunity can defined by
• - infection by foreign substances
• - the state of relative insusceptibility of an
  animal to infection by
  disease-producing organism or to the harmful
  effects of their poisons (toxins).
• Immune response the reaction of the body to
  foreign or potentially dangerous substances
  (antigen).

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Definition

• Antigen
• immunogen
• Any substances capable of stimulating an
  immune response, usually a protein or a
  large carbohydrate that is foreign to the body.

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Antibody

• immunoglobulin
• Protein compounds produced by plasma cells in
  response to specific antigens and having the
  capacity to react against the antigens
• Two functions of antibody
• merge with antigen
• activate process of destroy antigen by
  phagocytosis

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What is an Antigen?

• An antigen is any molecule or structure
• that is could trigger the immune response system
• A lymphocyte actually recognizes and binds
• to just a small, accessible portion of the
  antigen called an epitope

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What are Antibodies?

• Proteins produced by plasma cells (B lymphocytes)
  that recognize foreign antigens and prevent them
  from causing disease.

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Antibody Structure

• Each antibody consists of 4 polypetide chains
• two short polypeptides, light chains,
• two identical long chains, heavy chains.
• Antibodies with the same variable segments have
  identical clefts
• therefore recognize the same antigen.
• The 4 polypeptide chains are held together by
  covalent disulfide (-S-S-) bonds.

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Antibody Structure Function
Attachment of an antibody Now marks the
invader for ingestion by phagocytotic cells
(eg. WBC)
The antigen binding site is specific to the
protein coat of a given bacteria or virus
(species specific).
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Antibody Structure
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Immunoglobulin Classes

• Based on differences in structure of constant
  regions on heavy chains, antibody can be divided
  into 5 classes
• IgM
• IgG
• IgA
• IgD
• IgE

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