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TRANSCRIPT
Essentials of Human Anatomy & Physiology
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Seventh EditionElaine N. Marieb
Chapter 12The Lymphatic System
and Body Defenses
Lymph NodesLymph Nodes
Slide 12.6b
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Figure 12.3
The Lymphatic SystemThe Lymphatic System
Slide 12.1Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Two parts
Lymphatic vessels
Lymphoid tissues and organs
Lymphatic system functions
Transport fluids back to the blood
Play essential roles in body defense and resistance to disease
Absorb digested fat at the intestinal villi
Lymphatic CharacteristicsLymphatic Characteristics
Slide 12.2Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Lymph – excess tissue fluid carried by lymphatic vessels
Properties of lymphatic vessels One way system toward the heart
No pump
Lymph moves toward the heart
Milking action of skeletal muscle
Rhythmic contraction of smooth muscle in vessel walls
Lymphatic VesselsLymphatic Vessels
Slide 12.3b
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Figure 12.1
Lymphatic VesselsLymphatic Vessels
Slide 12.4a
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Lymphatic collecting vessels
Collects lymph from lymph capillaries
Carries lymph to and away from lymph nodes
Figure 12.2
Lymphatic VesselsLymphatic Vessels
Slide 12.4b
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Lymphatic collecting vessels (continued)
Returns fluid to circulatory veins near the heart
Right lymphatic duct
Thoracic ductFigure 12.2
LymphLymph
Slide 12.5a
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Materials returned to the blood Water Blood cells Proteins
LymphLymph
Slide 12.5b
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Harmful materials that enter lymph vessels Bacteria
Viruses
Cancer cells
Cell debris
Lymph NodesLymph Nodes
Slide 12.6a
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Filter lymph before it is returned to the blood
Defense cells within lymph nodes
Macrophages – engulf and destroy foreign substances
Lymphocytes – provide immune response to antigens
Lymph NodesLymph Nodes
Slide 12.6b
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Figure 12.3
Lymph Node StructureLymph Node Structure
Slide 12.7b
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Figure 12.4
Other Lymphoid OrgansOther Lymphoid Organs
Slide 12.9Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Several other organs contribute to lymphatic function
Spleen
Thymus
Tonsils
Peyer’s patchesFigure 12.5
The SpleenThe Spleen
Slide 12.10
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Located on the left side of the abdomen
Filters blood
Destroys worn out blood cells
Forms blood cells in the fetus
Acts as a blood reservoir
The ThymusThe Thymus
Slide 12.11
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Located low in the throat, overlying the heart
Functions at peak levels only during childhood
Produces hormones (like thymosin) to program lymphocytes
TonsilsTonsils
Slide 12.12
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Small masses of lymphoid tissue around the pharynx
Trap and remove bacteria and other foreign materials
Tonsillitis is caused by congestion with bacteria
Peyer’s PatchesPeyer’s Patches
Slide 12.13
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Found in the wall of the small intestine
Resemble tonsils in structure
Capture and destroy bacteria in the intestine
Mucosa-Associated Lymphatic Mucosa-Associated Lymphatic Tissue (MALT)Tissue (MALT)
Slide 12.14
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Includes:
Peyer’s patches
Tonsils
Other small accumulations of lymphoid tissue
Acts as a guard to protect respiratory and digestive tracts
Body DefensesBody Defenses
Slide 12.15a
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The body is constantly in contact with bacteria, fungi, and viruses (pathogens)
The body has two defense systems for foreign materials
Nonspecific defense system
Mechanisms protect against a variety of invaders
Responds immediately to protect body from foreign materials
Body DefensesBody Defenses
Slide 12.15b
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Specific defense system
Specific defense is required for each type of invader
Also known as the immune system
Nonspecific Body DefensesNonspecific Body Defenses
Slide 12.16
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Body surface coverings
Intact skin
Mucous membranes
Specialized human cells
Chemicals produced by the body
Surface Membrane Barriers – Surface Membrane Barriers – First Line of DefenseFirst Line of Defense
Slide 12.17a
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The skin
Physical barrier to foreign materials
pH of the skin is acidic to inhibit bacterial growth
Sebum is toxic to bacteria
Vaginal secretions are very acidic
Surface Membrane Barriers – Surface Membrane Barriers – First Line of DefenseFirst Line of Defense
Slide 12.17b
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Stomach mucosa
Secretes hydrochloric acid
Has protein-digesting enzymes
Saliva and lacrimal fluid contain lysozyme
Mucus traps microogranisms in digestive and respiratory pathways
Defensive CellsDefensive Cells
Slide 12.18a
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Phagocytes (neutrophils and macrophages)
Engulfs foreign material into a vacuole
Enzymes from lysosomes digest the material
Figure 12.6b
Macrophage attacking e-coli.
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Macrophage attacking e-coli.
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Defensive CellsDefensive Cells
Slide 12.18b
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Natural killer cells
Can lyse and kill cancer cells
Can destroy virus- infected cells
Figure 12.6b
Inflammatory Response - Inflammatory Response - Second Line of DefenseSecond Line of Defense
Slide 12.19
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Triggered when body tissues are injured
Produces four cardinal signs Redness
Heat
Swelling
Pain
Results in a chain of events leading to protection and healing
Functions of the Inflammatory Functions of the Inflammatory ResponseResponse
Slide 12.20
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Prevents spread of damaging agents
Disposes of cell debris and pathogens
Sets the stage for repair
Steps in the Inflammatory ResponseSteps in the Inflammatory Response
Slide 12.21
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Figure 12.7
Antimicrobial ChemicalsAntimicrobial Chemicals
Slide 12.22a
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Complement A group of at
least 20 plasma proteins
Activated when they encounter and attach to cells (complement fixation) Figure 12.8
Antimicrobial ChemicalsAntimicrobial Chemicals
Slide 12.22b
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Complement (continued)
Damage foreign cell surfaces
Will rupture or lyse the foreign cell membrane
Figure 12.8
Antimicrobial ChemicalsAntimicrobial Chemicals
Slide 12.22c
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Interferon
Secreted proteins of virus-infected cells
Bind to healthy cell surfaces to inhibit viruses binding
Interferons are a family species-specific proteins synthesized by eukaryotic cells in response to viruses and a variety of natural and synthetic stimuli. There are several different interferons commonly used as therapeutics, termed alpha, beta, and gamma. These peptides are used to treat hairy cell leukemia, AIDS-related Kaposi's sarcoma, laryngeal papillomatosis, genital warts, and chronic granulomatous disease. Side effects include black tarry stools, blood in the urine, confusion, and loss of balance.
FeverFever
Slide 12.23
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Abnormally high body temperature
Hypothalmus heat regulation can be reset by pyrogens (secreted by white blood cells)
High temperatures inhibit the release of iron and zinc from liver and spleen needed by bacteria
Fever also increases the speed of tissue repair
Specific Defense: The Immune Specific Defense: The Immune System – Third Line of DefenseSystem – Third Line of Defense
Slide 12.24
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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 12.25
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Humoral immunity
Antibody-mediated immunity
Cells produce chemicals for defense
Cellular immunity
Cell-mediated immunity
Cells target virus infected cells
Antigens (Nonself)Antigens (Nonself)
Slide 12.26
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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 12.27
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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 foreign
Restricts donors for transplants
AllergiesAllergies
Slide 12.28
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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
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Lymphocytes Originate from hemocytoblasts in the red bone
marrow
B lymphocytes become immunocompetent in the bone marrow
T lymphocytes become immunocompetent in the thymus
Macrophages Arise from monocytes
Become widely distributed in lymphoid organs
Activation of LymphocytesActivation of Lymphocytes
Slide 12.30
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Figure 12.9
Humoral (Antibody-Mediated) Humoral (Antibody-Mediated) Immune ResponseImmune Response
Slide 12.31a
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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) Humoral (Antibody Mediated) Immune ResponseImmune Response
Slide 12.31b
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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 12.32
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Figure 12.10
Active ImmunityActive Immunity
Slide 12.34
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Your B cells encounter antigens and produce antibodies
Active immunity can be naturally or artificially acquired
Figure 12.12
Passive ImmunityPassive Immunity
Slide 12.35
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Antibodies are obtained from someone else Conferred naturally from a mother to her
fetus
Conferred artificially from immune serum or gamma globulin
Immunological memory does not occur
Protection provided by “borrowed antibodies”
Antibodies (Immunoglobulins) (Igs)Antibodies (Immunoglobulins) (Igs)
Slide 12.37
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Soluble proteins secreted by B cells (plasma cells)
Carried in blood plasma
Capable of binding specifically to an antigen
Antibody ClassesAntibody Classes
Slide 12.39
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Antibodies of each class have slightly different roles
Five major immunoglobulin classes – (Do Not Need to know!) 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
Cellular (Cell-Mediated) Immune Cellular (Cell-Mediated) Immune ResponseResponse
Slide 12.42
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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 12.43
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Figure 12.15
T Cell ClonesT Cell Clones
Slide 12.44a
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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 12.44b
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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 12.45
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Figure 12.16
Organ Transplants and RejectionOrgan Transplants and Rejection
Slide 12.46a
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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 12.46b
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Autografts and isografts are ideal donors
Xenografts are never successful
Allografts are more successful with a closer tissue match
Disorders of Immunity: Disorders of Immunity: ImmunodeficienciesImmunodeficiencies
Slide 12.49
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Production or function of immune cells or complement is abnormal
May be congenital or acquired
Includes AIDS – Acquired Immune Deficiency Syndrome
Disorders of Immunity: Disorders of Immunity: Autoimmune DiseasesAutoimmune Diseases
Slide 12.50a
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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: Disorders of Immunity: Autoimmune DiseasesAutoimmune Diseases
Slide 12.50b
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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: Disorders of Immunity: Autoimmune DiseasesAutoimmune Diseases
Slide 12.50c
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Examples of autoimmune diseases (continued)
Systemic lupus erythematosus (SLE) – affects kidney, heart, lung and skin
Glomerulonephritis – impairment of renal function
• HIV targets cells
• Retrovirus attaches to CD4 receptors of T helper cells
– Transmission: Body fluids, i.e., blood, semen, breast milk, vaginal secretions
Immune Deficiency: AIDS
The Structure of HIV
Figure 9.19
Time Course of the Progression of AIDS after HIV Infection
Figure 9.21
•AIDS progression:
–Phase I: few weeks to a few years; flu like symptoms, swollen lymph nodes, chills, fever, fatigue, body aches. Virus is
multiplying, antibodies are made but ineffective for complete virus removal
–Phase II: within six months to 10 years; opportunistic infections present, Helper T cells affected, 5% may not
progress to next phase
–Phase III: Helper T cells fall below 200 per cubic millimeter of blood AND the person has an opportunistic infection or type
of cancer. Person is now termed as having “AIDS” May include pneumonia, meningitis, tuberculosis, encephalitis,
Kaposi’s sarcoma, and non-Hodgkin’s lumphoma….
• More than 36 million infected with HIV worldwide
• Most infections in sub-Sahara of Africa
• Increasing spread in Asia and India
• Most often spread by heterosexual contact outside U.S.
AIDS Pandemic