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Chapter 22, part 2. The Lymphatic System and Immunity. 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 - PowerPoint PPT Presentation
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Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Fundamentals of
Anatomy & PhysiologySIXTH EDITION
Frederic H
. Martini
PowerPoint® Lecture Slide Presentation prepared by Dr. Kathleen A. Ireland, Biology Instructor, Seabury Hall, Maui, Hawaii
Chapter 22, part 2
The Lymphatic System and Immunity
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
• 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
The Thymus
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Figure 22.8 The Thymus
Figure 22.8a-c
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• 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
The Spleen
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Figure 22.9 The Spleen
Figure 22.9a-c
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• 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
Lymphatic system and body defenses
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SECTION 22-3 Nonspecific Defenses
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• Keep hazardous organisms outside the body
• Includes hair, epithelia, secretions of integumentary and digestive systems
Nonspecific Defenses, Physical barriers
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Figure 22.10 Nonspecific Defenses (Part 1 - Physical Barriers)
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• 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
Nonspecific Defenses, Phagocytes
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Figure 22.10 Nonspecific Defenses(Part 2 - Phagocytes)
Figure 22.10
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• Constant monitoring of normal tissue by NK cells
• NK cells
• Recognize cell surface markers on foreign cells
• Destroy cells with foreign antigens
Nonspecific Defenses, Immunological surveillance
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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
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Figure 22.10
Figure 22.10 Nonspecific Defenses(Part 3 - Immunological Surveillance)
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Figure 22.11 How Natural Killer Cells Kill Cellular Targets
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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)
Figure 22.10
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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 22.12 Complement Activation
Figure 22.12
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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)
Figure 22.10
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Figure 22.13 Inflammation
Figure 22.13
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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
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Figure 22.10
Figure 22.10 Nonspecific Defenses(Part 7 - Fever)