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Anatomy & Physiology
SIXTH EDITION
Chapter 22, part 2
The Lymphatic System
and Immunity
PowerPoint® Lecture Slide Presentation prepared by
Dr. Kathleen A. Ireland, Biology Instructor, Seabury Hall, Maui, Hawaii
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Frederic H. Martini
Fundamentals of
The Thymus
• Located behind sternum in anterior mediastinum
• Capsule
• Two lobes
• Divided into lobules, each with a cortex and
medulla
• Cortical lymphocytes surrounded by reticular
endothelial cells
• Maintain blood–thymus barrier
• Secretes thymic hormones: thymosins,
thymopoietins, and thymulin
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Figure 22.8 The Thymus
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Figure 22.8a-c
The Spleen
• Largest mass of lymphoid tissue
• Cellular components form pulp
• Red pulp contains RBC
• White pulp similar to lymphoid nodules
• Spleen functions include
• Removal of abnormal blood cells and other
blood components
• Storage of iron
• Initiation of the specific immune response
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Figure 22.9 The Spleen
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Figure 22.9a-c
Lymphatic system and body defenses
• Nonspecific defenses
• Do not distinguish one type of threat from
another
• 7 types
• Specific defenses
• Protect against particular threats
• Depend upon the activation of lymphocytes
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SECTION 22-3
Nonspecific Defenses
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Nonspecific Defenses, Physical barriers
• Keep hazardous organisms outside the body
• Includes hair, epithelia, secretions of
integumentary and digestive systems
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Figure 22.10 Nonspecific Defenses
(Part 1 - Physical Barriers)
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Figure 22.10
Nonspecific Defenses, Phagocytes
• Remove cellular debris and respond to invasion
by foreign pathogens
• Monocyte-macrophage system - Fixed and free
• Microphages – Neutrophils and eosinophils
• Move by diapedesis
• Exhibit chemotaxis
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Figure 22.10 Nonspecific Defenses
(Part 2 - Phagocytes)
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Figure 22.10
Nonspecific Defenses, Immunological
surveillance
• Constant monitoring of normal tissue by NK cells
• NK cells
• Recognize cell surface markers on foreign cells
• Destroy cells with foreign antigens
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NK cell activation
• Recognition of unusual surface proteins
• Rotation of the Golgi toward the target cell and
production of perforins
• Release of perforins by exocytosis
• Interaction of perforins causing cell lysis
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Figure 22.10 Nonspecific Defenses
(Part 3 - Immunological Surveillance)
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Figure 22.10
Figure 22.11 How Natural Killer Cells Kill
Cellular Targets
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Figure 22.11
Nonspecific Defenses, Interferons (cytokines)
• Small proteins released by virally infected cells
• Trigger the production of antiviral proteins
• Three major types of interferons are:
• Alpha– produced by leukocytes and
attract/stimulate NK cells
• Beta– secreted by fibroblasts causing slow
inflammation
• Gamma – secreted by T cells and NK cells
stimulate macrophage activity
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Figure 22.10 Nonspecific Defenses
(Part 4 - Interferons)
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Figure 22.10
Nonspecific Defenses, Complement system
• Cascade of ~11 plasma complement proteins (C)
• Destroy target cell membranes
• Stimulate inflammation
• Attract phagocytes
• Enhance phagocytosis
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Complement proteins interact with on another
via two pathways
• Classical
• Alternative
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Figure 22.10 Nonspecific Defenses
(Part 5 - Complement System)
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Figure 22.10
Figure 22.12 Complement Activation
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Figure 22.12
Nonspecific Defenses, Inflammation
• Localized tissue response to injury producing
• Swelling
• Redness
• Heat
• Pain
• Effects of inflammation include
• Temporary repair of injury
• Slowing the spread of pathogens
• Mobilization of local, regional, and systemic
defenses
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Figure 22.10 Nonspecific Defenses
(Part 6 - Inflammatory Response)
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Figure 22.10
Figure 22.13 Inflammation
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Figure 22.13
Nonspecific Defenses, Fever
• Maintenance of a body temperature above 37.2oC
(99oF)
• Pyrogens reset the hypothalamic thermostat and
raise body temperature
• Pathogens, toxins, antigen-antibody complexes
can act as pyrogens
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Figure 22.10 Nonspecific Defenses
(Part 7 - Fever)
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Figure 22.10