The body

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The bodys defenses
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Reading Ch. 43 Keywords

• Lines of defense
• Lymphatic system
• Inflammation
• Features of immune system
• Memory B-cells
• Primary and secondary immune responses
• Antibody
• Antigen
• Agglutination
• macrophage

• lymphocyte
• Phagocytosis
• Complement system
• Humoral immunity
• Cell-mediated immunity
• B cell
• Helper T cell
• Cytotoxic T cell

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Overview
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Non-specific

• First line
• Skin
• Mucous membranes
• Secretions of skin and mucous membranes
• Second line
• Phagocytic white blood cells
• Anti-microbial proteins
• Inflammatory response

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Second line of defense - macrophage
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Inflamation
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Focus on immune system(3rd line of defense)

• Protects body against specific invaders

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Key features

• Specificity
• Diversity
• Memory
• Self/Nonself Recognition

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First the major playersLymphocytes
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The lymphatic system
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Two types of immune responses

• Humoral
• Cell-mediated

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Key features

• Specificity
• Diversity
• Memory
• Self/Nonself Recognition

Humoral immunity
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Humoral immunity B cells and clonal selection
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There are a variety of B cells
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One B cell becomes activated and proliferates
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Some B cells become plasma cells that secrete
antibodies
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Some B cells become plasma cells that secrete
antibodies
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Some B cells become memory cells
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Some B cells become memory cells
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Memory cells function in secondary immune response

• Primary immune response - first exposure
• Secondary immune response - second exposure

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Primary and secondary immune responses
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Summary

• Lag in primary response due to proliferation from
  a single clone
• Secondary (2) response is from multiple memory
  cells
• 2 response has less of a lag and is stronger

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What do antibodies do?
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Inactivate antigens
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Neutralization
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Agglutination of antigen bearing particles
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Precipitation of soluble antigens
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Inactivate antigens

• Neutralization
• Agglutination
• Precipitation

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These mechanisms enhance phagocytosis
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Antibodies inactivate antigens

• Neutralization of invaders
• Agglutination
• Precipitation of soluble antigens
• The above enhance phagocytosis
• One final mechanism Complement system

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Complement system Step 1 attachment to pathogen
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Step 2 Recruitment of complement proteins
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Step 3 Activation
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Step 4 pore formation
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Summary

• Complement proteins interact with antibodies to
  kill invading cells
• Binding of antibody is followed by attachment of
  complement proteins
• Protein complex becomes activated
• Pore is formed in pathogens membrane
• Goodbye pathogen

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Two types of immune responses

• Humoral
• Cell-mediated

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Cell-mediated

• Complicated, involves cellular components
• Will briefly touch on role of helper T cells

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Recall that T cells are the other type of
lymphocyte
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Cell-mediated response happens at the same time
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Macrophage engulfs invader
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Antigens from invader are presented on macrophage
cell surface
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Helper T cells are recruited
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Helper T cells proliferate and activate cytotoxic
T cells and B cells
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T cells infected with HIV