Notes-Lymphatic System, Pt. 2

8/10/2019 Notes-Lymphatic System, Pt. 2

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Essentials of Human Anatomy & Physiology

Copyright 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Slides 12.23 12.52

Seventh Edition

Elaine N. Marieb

Chapter 12

The Lymphatic System

and Body Defenses

Lecture Slides in PowerPoint by Jerry L. Cook


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Specific Defense: The Immune

SystemThird Line of Defense

Antigen specificrecognizes and actsagainst particularforeign substances

Systemicnot restricted to the initialinfection site

Has memoryrecognizes and mountsa stronger attack on previouslyencountered pathogens


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Antigens (Nonself)

Any substance capable of exciting theimmune system and provoking an immuneresponse

Examples of common antigens

Foreign proteins

Nucleic acids

Large carbohydrates

Some lipids

Pollen grains

Microorganisms


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Self-Antigens

Human cellshave manysurface proteins

Our immune cells do not attack our ownproteins

Our cells in another persons body cantrigger an immune response becausethey are foreign

Restricts donors for transplants


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Antibody Structure

Four amino acidchains linked by

disulfide bonds Two identical

amino acid

chains are linkedto form a heavychain

Figure 12.13b


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Antibody Structure

The other two

identical chainsare light chains

Specific antigen-

binding sites arepresent

Figure 12.13b


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Antibody Function

Antibodies inactivate antigens in anumber of ways

Complementfixation

Neutralization

Agglutination

Precipitation


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Antibody Function

Figure 12.14


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Cells of the Immune System

Lymphocytes Originate from hemocytoblasts in the red bone

marrow

B lymphocytes become immunocompetent inthe bone marrow

T lymphocytes become immunocompetent inthe thymus

MacrophagesArise from monocytes

Become widely distributed in lymphoid organs


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Humoral (Antibody-

Mediated) Immune

Response

B lymphocytes with

specific receptors bindto a specific antigen

The binding event activates the

lymphocyte to undergo clonal selectionA large number of clones are produced

(primary humoral response)


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Humoral

(Antibody Mediated)

Immune Response

Most B cells become plasma cells

Produce antibodies to destroy antigens

Activity lasts for four or five days Some B cells become long-lived memory

cells (secondary humoral response)


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Humoral Immune Response

Figure 12.10


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Secondary Response

Memory cellsare long-lived

A second

exposurecauses a rapidresponse

The secondaryresponse isstronger andlonger lasting

Figure 12.11


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Active Immunity

Your B cellsencounterantigens and

produceantibodies

Active immunity

can be naturallyor artificiallyacquired

Figure 12.12


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Cellular (Cell-Mediated) Immune

Response

Antigens must be presented bymacrophages to an immunocompetent

T cell (antigen presentation) T cells must recognize nonself and self

(double recognition)

After antigen binding, clones form aswith B cells, but different classes of cellsare produced


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Cellular (Cell-Mediated) Immune

Response

Figure 12.15


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T Cell Clones

Cytotoxic T cells

Specialize in killing infected cells

Insert a toxic chemical (perforin)

Helper T cells

Recruit other cells to fight the invaders

Interact directly with B cells


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Summary of the Immune Response

Figure 12.16


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Organ Transplants and Rejection

Major types of grafts

Autograftstissue transplanted from onesite to another on the same person

Isograftstissue grafts from an identicalperson (identical twin)

Allograftstissue taken from an unrelated

person

Xenograftstissue taken from a differentanimal species


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Organ Transplants and Rejection

Autografts and isografts are idealdonors

Allografts are more successful with acloser tissue match

Xenografts arenever successful


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Disorders of Immunity: Allergies

(Hypersensitivity)

Abnormal, vigorous immune responses

Types of allergies

Immediate hypersensitivity

Triggered by release of histamine from IgEbinding to mast cells

Reactions begin within seconds of contact withallergen

Anaphylactic shockdangerous, systemicresponse


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Allergy Mechanisms


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Disorders of Immunity:

Immunodeficiencies

Production or function of immune cells

or complement is abnormal May be congenital or acquired

Includes AIDSAcquired ImmuneDeficiency Syndrome


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Disorders of Immunity: Autoimmune

Diseases

The immune system does not

distinguish between self and nonself The body produces antibodies and

sensitized T lymphocytes that attack its

own tissues


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Diseases

Examples of autoimmune diseases

Multiple sclerosiswhite matter of brain

and spinal cord are destroyedMyasthenia gravisimpairs

communication between nerves andskeletal muscles

Juvenile diabetesdestroys pancreaticbeta cells that produce insulin

Rheumatoid arthritisdestroys joints


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Diseases

Examples of autoimmune diseases

(continued)Systemic lupus erythematosus (SLE)

affects kidney, heart, lung and skin

Glomerulonephritisimpairment of renalfunction


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Developmental Aspects of the

Lymphatic System and Body Defenses

Except for thymus and spleen, thelymphoid organs are poorly developedbefore birth

A newborn has no functioninglymphocytes at birth; only passiveimmunity from the mother

If lymphatics are removed or lost, severeedema results, but vessels grow back intime

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Notes-Lymphatic System, Pt. 2