Essentials of Human Anatomy & Physiology

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Slides 12.23 – 12.52

Seventh EditionElaine N. Marieb

Chapter 12The Lymphatic System

and Body Defenses

FeverFever

Slide 12.23Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Abnormally high body temperature Hypothalmus heat regulation

can be reset upward in response to pyrogens (secreted by white blood cells)

High temperatures inhibit the release of iron and zinc from liver and spleen needed by bacteria for reproduction

Fever also increases the speed of tissue repair (due to higher metabolic rate of tissues)

Specific Defense: The Immune Specific Defense: The Immune System – Third Line of DefenseSystem – Third Line of Defense

Antigen specific – recognizes and acts against particular foreign substances

Systemic – not restricted to the initial infection site

Has memory – recognizes and mounts a stronger attack on previously encountered pathogens

Types of ImmunityTypes of Immunity

Slide 12.25Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Humoral immunity (operates in fluids of body) Antibody-mediated immunity Cells produce chemicals for

defense Cellular immunity (lymphocytes

themselves defend the body) Cell-mediated immunity Cells target virus infected cells,

cancer cells, cells of foreign grafts

Humoral vs. Cell-Mediated Response

Antigens (Nonself)Antigens (Nonself)

Slide 12.26Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Any substance capable of exciting the immune system and provoking an immune response

Examples of common antigens Foreign proteins Nucleic acids Large carbohydrates Some lipids Pollen grains Microorganisms

Self-AntigensSelf-Antigens

Slide 12.27Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Human cells have many surface proteins

Our immune cells do not attack our own proteins

Our cells in another person’s body can trigger an immune response because they are foreignRestricts donors for transplants

AllergiesAllergies

Slide 12.28Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Many small molecules (called haptens or incomplete antigens) are not antigenic, but link up with our own proteins

The immune system may recognize and respond to a protein-hapten combination

The immune response is harmful rather than protective because it attacks our own cells

Cells of the Immune SystemCells of the Immune System

Slide 12.29

Lymphocytes Originate from

hemocytoblasts in the red bone marrow

B lymphocytes become immunocompetent in the bone marrow

T lymphocytes become immunocompetent in the thymus

Immunocompetence-capability to respond to a certain antigen by binding to it

Cells of the Immune SystemCells of the Immune System

Slide 12.29Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Macrophages Arise from cells formed in the bone marrow “big” eaters that engulf foreign particles and

present fragments of these particles on their cell surfaces

Become widely distributed in lymphoid organs

Activation of LymphocytesActivation of Lymphocytes

Slide 12.30Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Figure 12.9

Humoral (Antibody-Mediated) Immune Humoral (Antibody-Mediated) Immune ResponseResponse

Slide 12.31aCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

B lymphocytes with specific receptors bind to a specific antigen

The binding event activates the lymphocyte to undergo clonal selection

A large number of clones are produced (primary humoral response)

Humoral (Antibody-Mediated) Immune Humoral (Antibody-Mediated) Immune ResponseResponse

Slide 12.31aCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

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)

Humoral Immune ResponseHumoral Immune Response

Slide 12.32Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Figure 12.10

Secondary Response (after exposure to Secondary Response (after exposure to the same antigen) --can be years laterthe same antigen) --can be years later

Slide 12.33Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Memory cells are long-lived

A second exposure causes a rapid response (since all preparations for the attack have been made)

The secondary response is stronger and longer lasting Figure 12.11

Humoral Immune ResponseHumoral Immune Response

Slide 12.32Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Figure 12.10

New army being made

Active Immunity-acquired when…Active Immunity-acquired when…

Slide 12.34Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Your B cells encounter antigens and produce antibodies

Active immunity can be naturally or artificially acquired

Figure 12.12

Passive ImmunityPassive Immunity

Slide 12.35Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Antibodies are obtained from someone else Conferred naturally from a

mother to her fetus, and to baby through milk

Conferred artificially from immune serum or gamma globulin (usu. for hepatitis)

Immunological memory does not occur

Protection provided by “borrowed antibodies”

Monoclonal Antibodies-one group of Monoclonal Antibodies-one group of borrowed antibodiesborrowed antibodies

Slide 12.36Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Antibodies prepared for clinical testing or diagnostic services

Produced from descendants of a single cell line, and exhibit specificity for one and only one antigen

Examples of uses for monoclonal antibodies Deliver cancer-fighting drugs to cancerous

tissues Diagnosis of hepatitis and rabies

Antibodies (Immunoglobulins) (Igs)Antibodies (Immunoglobulins) (Igs)

Slide 12.37Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Soluble proteins secreted by B cells (plasma cells)

Carried in blood plasma Capable of binding specifically to an

antigen

Antibody StructureAntibody Structure

Slide 12.38aCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Four amino acid chains linked by disulfide bonds

Two identical amino acid chains are linked to form a heavy chain

Figure 12.13b

Antibody StructureAntibody Structure

Slide 12.38bCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

The other two identical chains are light chains

Specific antigen-binding sites are present

Figure 12.13b

Antibody ClassesAntibody Classes

Slide 12.39Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Antibodies of each class have slightly different roles

Five major immunoglobulin classes IgM – can fix complement IgA – found mainly in mucus IgD – important in activation of B cell IgG – can cross the placental barrier IgE – involved in allergies

Antibody FunctionAntibody Function

Slide 12.40Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Antibodies inactivate antigens in a number of ways Complement fixation Neutralization Agglutination Precipitation

Antibody FunctionAntibody Function

Slide 12.41Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Figure 12.14

Cellular (Cell-Mediated) Immune Cellular (Cell-Mediated) Immune ResponseResponse

Slide 12.42Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Antigens must be presented by macrophages to an immunocompetent T cell (antigen presentation)

T cells must recognize nonself and self (double recognition)

After antigen binding, clones form as with B cells, but different classes of cells are produced

Cellular (Cell-Mediated) Immune Cellular (Cell-Mediated) Immune ResponseResponse

Slide 12.43Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Figure 12.15

T Cell ClonesT Cell Clones

Slide 12.44aCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

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

T Cell ClonesT Cell Clones

Slide 12.44bCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Suppressor T cells Release chemicals to suppress the activity

of T and B cells Stop the immune response to prevent

uncontrolled activity

A few members of each clone are memory cells

Summary of the Immune ResponseSummary of the Immune Response

Slide 12.45Copyright © 2003 Pearson Education, Inc. publishing as Benjamin CummingsFigure 12.16

Organ Transplants and RejectionOrgan Transplants and Rejection

Slide 12.46aCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Major types of grafts Autografts – tissue transplanted from one

site to another on the same person Isografts – tissue grafts from an identical

person (identical twin) Allografts – tissue taken from an unrelated

person Xenografts – tissue taken from a different

animal species

Organ Transplants and RejectionOrgan Transplants and Rejection

Slide 12.46bCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Autografts and isografts are ideal donors

Xenografts are never successful Allografts are more successful with a

closer tissue match

Disorders of Immunity: Allergies Disorders of Immunity: Allergies (Hypersensitivity)(Hypersensitivity)

Slide 12.47aCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Abnormal, vigorous immune responses Types of allergies

Immediate hypersensitivity Triggered by release of histamine from IgE

binding to mast cells Reactions begin within seconds of contact with

allergen Anaphylactic shock – dangerous, systemic

response

Disorders of Immunity: Allergies Disorders of Immunity: Allergies (Hypersensitivity)(Hypersensitivity)

Slide 12.47bCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Types of allergies (continued) Delayed hypersensitivity

Triggered by the release of lymphokines from activated helper T cells

Symptoms usually appear 1–3 days after contact with antigen

Allergy MechanismsAllergy Mechanisms

Slide 12.48Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Figure 12.17

Disorders of Immunity: Disorders of Immunity: ImmunodeficienciesImmunodeficiencies

Slide 12.49Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Production or function of immune cells or complement is abnormal

May be congenital or acquired Includes AIDS – Acquired Immune

Deficiency Syndrome

Disorders of Immunity: Autoimmune Disorders of Immunity: Autoimmune DiseasesDiseases

Slide 12.50aCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

The immune system does not distinguish between self and nonself

The body produces antibodies and sensitized T lymphocytes that attack its own tissues

Disorders of Immunity: Autoimmune Disorders of Immunity: Autoimmune DiseasesDiseases

Slide 12.50bCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Examples of autoimmune diseases Multiple sclerosis – white matter of brain

and spinal cord are destroyed Myasthenia gravis – impairs

communication between nerves and skeletal muscles

Juvenile diabetes – destroys pancreatic beta cells that produce insulin

Rheumatoid arthritis – destroys joints

Disorders of Immunity: Autoimmune Disorders of Immunity: Autoimmune DiseasesDiseases

Slide 12.50cCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Examples of autoimmune diseases (continued) Systemic lupus erythematosus (SLE) –

affects kidney, heart, lung and skin Glomerulonephritis – impairment of renal

function

Self Tolerance BreakdownSelf Tolerance Breakdown

Slide 12.51aCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Inefficient lymphocyte programming Appearance of self-proteins in the

circulation that have not been exposed to the immune system Eggs Sperm Eye lens

Self Tolerance BreakdownSelf Tolerance Breakdown

Slide 12.51bCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Cross-reaction of antibodies produced against foreign antigens with self-antigens Rheumatic fever

Developmental Aspects of the Developmental Aspects of the Lymphatic System and Body DefensesLymphatic System and Body Defenses

Slide 12.52Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Except for thymus and spleen, the lymphoid organs are poorly developed before birth

A newborn has no functioning lymphocytes at birth; only passive immunity from the mother

If lymphatics are removed or lost, severe edema results, but vessels grow back in time