Lymphatic system and body defenses

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings

• 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


SECTION 22-3 Nonspecific Defenses


• Keep hazardous organisms outside the body

• Includes hair, epithelia, secretions of integumentary and digestive systems

Nonspecific Defenses, Physical barriers

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Figure 22.10

Figure 22.10 Nonspecific Defenses (Part 1 - Physical Barriers)


• 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


Figure 22.10 Nonspecific Defenses(Part 2 - Phagocytes)

Figure 22.10


• 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


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


Figure 22.10 Nonspecific Defenses(Part 3 - Immunological Surveillance)


Figure 22.11 How Natural Killer Cells Kill Cellular Targets


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


Figure 22.10 Nonspecific Defenses(Part 4 - Interferons)

Figure 22.10


Nonspecific Defenses, Complement system

• Cascade of ~11 plasma complement proteins (C)

• Destroy target cell membranes

• Stimulate inflammation

• Attract phagocytes

• Enhance phagocytosis


Complement proteins interact with on another via two pathways

• Classical

• Alternative


Figure 22.10 Nonspecific Defenses(Part 5 - Complement System)


Figure 22.12 Complement Activation

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


Figure 22.10 Nonspecific Defenses(Part 6 - Inflammatory Response)

Figure 22.10


Figure 22.13 Inflammation

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


Figure 22.10 Nonspecific Defenses(Part 7 - Fever)


SECTION 22-4 Specific Defenses


Forms of immunity

• Innate immunity

• Genetically determined

• Present at birth

• Acquired immunity

• Not present at birth

• Achieved by exposure to antigen

• Active immunity

• Passive immunity


Figure 22.14 Types of Immunity

Figure 22.14


Properties of immunity

• Specificity – activated by and responds to a specific antigen

• Versatility – is ready to confront any antigen at any time

• Memory – “remembers” any antigen it has encountered

• Tolerance – responds to foreign substances but ignores normal tissues


The immune system response

• Antigen triggers an immune response

• Activates T cells and B cells

• T cells are activated after phagocytes exposed to antigen

• T cells attack the antigen and stimulate B cells

• Activated B cells mature and produce antibody

• Antibody attacks antigen


Figure 22.15 An Overview of the Immune Response


SECTION 22-5 T cells and Cell-mediated Immunity


Major types of T cells

• Cytotoxic T cells (TC) – attack foreign cells

• Helper T cells (TH) – activate other T cells and B cells

• Suppressor T cells (TS) – inhibit the activation of T and B cells


Antigen presentation

• Antigen-glycoprotein combination appears on a cell membrane

• Called MHC proteins (Major Histocompatibility Complex)

• Coded for by genes of the MHC

• T-cells sensitive to the antigen are activated upon contact


MHC classes

• Class I – found on all nucleated cells

• Class II – found on antigen presenting cells and lymphocytes


Lymphocytes respond to antigens bound to either class I or class II MHC proteins

• Antigen recognition

• T cell membranes contain CD markers

• CD3 markers present on all T cells

• CD8 markers on cytotoxic and suppressor T cells

• CD4 markers on helper T cells


Figure 22.16 Antigens and MHC Proteins

Figure 22.16



Figure 22.16a



Figure 22.16b


Activation of CD8 cells

• Responds quickly giving rise to other T cells

• Cytotoxic T cells – seek out and destroy abnormal cells• lymphotoxin

• Memory TC cells – function during a second exposure to antigen

• Suppressor T cells – suppress the immune response


Figure 22.17 Antigen Recognition and the Activation of Cytotoxic T Cells


Figure 22.17 Antigen Recognition and the Activation of Cytotoxic T Cells

Animation: Cytotoxic T Cell ActivationPLAY


Activation of CD4 T cells by antigens presented on class II MHC proteins

• Produces helper T cells and memory T cells

• Activated helper T cells

• Secrete lymphokines that coordinate specific and nonspecific defenses

• Enhance nonspecific defenses

• Stimulate the activity of NK cells

• Promote activation of B cells


Figure 22.18 Antigen Recognition and Activation of Helper T cells

Animation: Antigen Recognition and Helper T Cell ActivationPLAY


Figure 22.19 A Summary of the Pathways of T Cell Activation


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 4

The Lymphatic System and Immunity


SECTION 22-6 B Cells and Antibody-mediated Immunity


B cell sensitization of activation

• Sensitization – the binding of antigens to the B cell membrane antibodies

• Antigens then displayed on B cell Class II MHC

• TH cells activated by same antigen stimulate B cell

• Active B cell differentiates into Memory B Cell or Plasma cell

• Plasma cells synthesize and release antibody


Figure 22.20 The Sensitization and Activation of B Cells

Animation: B Cells and Antibody ProductionPLAY


Antibodies structure

• Antibodies are Y-shaped proteins consisting of:

• Two parallel polypeptide chains

• Heavy chains and light chains

• Constant region and variable region

• Antigen binding site


Figure 22.21 Antibody Structure

Figure 22.21



Figure 22.21a



Figure 22.21b-d


Actions of antibodies include:

• Neutralization

• Agglutination and precipitation

• Activation of complement

• Attraction of phagocytes

• Opsinization

• Stimulation of inflammation

• Prevention of adhesion


Classes of Antibodies (immunoglobins)

• IgG – resistance against many viruses, bacteria and bacterial toxins

• IgE – accelerates local inflammation

• IgD – found on the surface of B cells

• IgM – first type secreted after antigen arrives

• IgA – primarily found in glandular sec


Primary and secondary antibody response

• Primary response

• Takes about two weeks to develop

• Produced by plasma cells

• Secondary response

• Rapid increase in IgG

• Maximum antibody titer app


Figure 22.22 The Primary and Secondary Immune Responses


Figure 22.23 An Integrated Summary of the Immune Response


SECTION 22-7 Normal and Abnormal Resistance


Development of the Immune Response

• Immunological competence

• The ability to demonstrate an immune response after exposure to an antigen

• Fetuses receive immunity from the maternal bloodstream

• Infants acquire immunity following exposure


Immune disorders

• Autoimmune disorders

• Immune response mistakenly targets normal cells

• Immunodeficiency diseases

• Immune system does not develop properly or is blocked


Allergies

• Inappropriate or excessive immune response to allergens

• Anaphylaxis

• Circulating allergen affects mast cells throughout body


Figure 22.26 The Mechanism of Anaphylaxis

Figure 22.26


Stress and the immune response

• Interleukin-1 released by active macrophages

• Triggers release of ACTH resulting in glucocorticoid release

• Moderates the immune response

• Lowers resistance to disease


Stress can cause the following:

• Depression of the inflammatory response

• Phagocytic reduction

• Inhibition of interleukin secretion


• The structure and function of lymphatic cells, tissues and organs

• The body’s nonspecific defenses and the components and mechanisms of each

• Specific resistance, cell-mediated immunity and antibody mediated immunity

• The role of the T cell, B cell and antibodies in specific immunity

You should now be familiar with:

Lymphatic system and body defenses

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