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Inquiry into Life
Twelfth Edition
Sylvia S. Mader
Chapter 13
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13.1 The Lymphatic System
• The Lymphatic System
– Lymphatic Vessels
– Lymphatic Organs
• The Lymphatic System Contributes to
Homeostasis
– Returning excess tissue fluid to the bloodstream
– Absorbing fat from the digestive tract and transports
them to the bloodstream
– Helps defend the body against disease
Lymphatic System
13.1 Lymphatic System
• Lymphatic Vessels
– A one-way system
– Fluid inside is called lymph
• Consists of water and solutes
– Lymphatic capillaries
•
•
•
•
Found in most areas of the body
Small, closed-ended vessels
Capillaries merge into larger vessels
These larger vessels carry the lymph into the thoracic and
lymphatic ducts
• Lymph is returned to the bloodstream
13.1 Lymphatic System
• Lymphatic Vessels Continued
– Larger Lymphatic Vessels
• Valves prevent backflow
• Movement of lymph is dependent on skeletal muscle
contractions
– Edema
• Localized swelling caused by accumulation of fluids in the
tissues (not drained by the lymphatic system)
13.1 Lymphatic System
• Lymphatic Organs
– Contain a large number of lymphocytes, a
type of white blood cells
• B lymphocytes (B cells)
• T lymphocytes (T cells)
The Lymphatic Organs
13.1 Lymphatic System
• Primary Lymphatic Organs
– Red Bone Marrow
• Site of blood cell production
• B-cells mature in the bone marrow
– Thymus Gland
• Site of T-cell maturation
13.1 Lymphatic System
• Secondary Lymphatic Organs
– Spleen
• Cleanses the blood
– Lymph nodes
• Cleanses lymph
13.2 Innate and Acquired Immunity
• Innate immunity mechanisms are fully functional
without previous exposure to a unwanted
substance.
• Acquired immunity is dependent upon exposure
to specific antigens.
• Antigen: Any molecule that stimulates an
immune response.
13.2 Innate and Acquired Immunity
• Innate Immunity
– Physical and Chemical Barriers
– Inflammation
– Phagocytes and Natural Killer Cells
– Protective Proteins
13.2 Innate and Acquired Immunity
• Innate Immunity
– Physical and Chemical Barriers
• Skin and mucous membranes serve as protective barriers
• Upper respiratory tract has cilia to remove trapped particles
• Oil glands (skin) secretes chemicals harmful to some
bacteria
• Stomach is acidic
• Bacteria (normal flora) in the intestines and other areas outcompete potential pathogens
13.2 Innate and Acquired Immunity
• Innate Immunity
– Inflammation
13.2 Innate and Acquired Immunity
• Innate Immunity
– Phagocytes
• Phagocytes engulf pathogens via endocytosis
– Neutrophils
– Monocytes / Macrophages
– Natural Killer Cells
• Destroy some virus-infected cells and cancer cells
by cell-to-cell contact
13.2 Innate and Acquired Immunity
• Complement System
– Cause holes to form in
the outer surface of
some bacteria and
viruses
• Interferons
– Proteins produced by
cells infected with a
virus that protects noninfected cells
13.2 Innate and Acquired Immunity
• Acquired Immunity
– These defenses are specific against an antigen, they
may take 5 to 7 days to become fully activated
– Depends upon lymphocytes
• B-cells
• T-cells
13.2 Innate and Acquired Immunity
• B cells and Antibody-Mediated Immunity
• Characteristics of B Cells
– Antibody-mediated immunity against pathogens
– Produced and mature in bone marrow
– Reside in lymph nodes and spleen, circulate in blood
and lymph
– Directly recognize antigen and then undergo clonal
selection
– Clonal expansion produces antibody-secreting
plasma cells as well as memory B-cells
Clonal Selection Theory as it Applies to
B-Cells
13.2 Innate and Acquired Immunity
• Structure of an
Antibody
– Antibodies are also called
immunoglobulins (Ig’s).
– Y-shaped
• Constant regions
• Variable regions
Classes of Antibodies
13.2 Innate and Acquired Immunity
• T cells and Cell-Mediated Immunity
– A macrophage presents a portion of an
antigen to T cells
– Types of T-cells
• Helper T-cells
• Cytotoxic T-cells
Clonal Selection Model as it Applies to
T cells
13.2 Innate and Acquired Immunity
• Characteristics of T-Cells
– Cell-mediated immunity against virus infected cells
and cancer cells
– Produced in bone marrow, mature in thymus
– Antigen must be presented in groove of an MHC
molecule
– Cytotoxic T cells destroy nonself protein-bearing cells
– Helper T cells secrete cytokines that control the
immune response
Cell-Mediated Immunity
13.3 Induced Immunity
• Active Immunity
– Develops naturally after a person is infected with an
antigen
– A person produces an immune response against an
antigen
– Can be induced by use of vaccines
– Is dependent upon the presence of Memory B Cells
and Memory T Cells in the body
13.3 Induced Immunity
• Vaccines are pathogens or their products that
have been treated so they are no longer able to
cause disease.
13.3 Induced Immunity
13.3 Induced Immunity
• Passive Immunity
– An individual is given
prepared antibodies to
combat disease
– Is temporary because
there are no memory
cells
13.3 Induced Immunity
• Immune Therapies
– Cytokines and Immunity
• Signaling molecules produced by T lymphocytes and
macrophages
• Interleukins
– Cytokines that enhance ability of T cells to fight cancer
– Have many potential uses in medicine
13.3 Induced Immunity
• Monoclonal Antibodies
– Group of plasma cells from
the same B cell all produce
same antibody
– Use of monoclonal
antibodies
• Diagnostic tests
– Ex: pregnancy tests
• Vehicles for drug delivery
• Identification of infections
13.4 Adverse Effects of
Immune Responses
• Allergies
– Hypersensitivities to Substances
– Immediate Allergic Response
• Can occur within seconds of exposure to an antigen
• IgE antibodies attach to mast cells
• Allergen attaches to IgE , causing mast cells to release
histamine
• Histamine is responsible for allergy symptoms
– Anaphylactic Shock
• Immediate allergic response where allergen enters the blood
stream
• Histamine causes a sudden, life-threatening drop in blood
pressure
• Epinephrine can counteract this reaction
13.4 Adverse Effects of
Immune Responses
• Blood-Type Reactions
– In the ABO system, the presence or absence of type A and type
B antigens on red blood cells determines a persons blood type.
– If antibodies are present against a type of blood, agglutination
occurs
– Transfusions
• Must consider recipient’s antibodies and donor’s antigens to prevent
agglutination and transfusion reaction
• Type O is universal donor
– Neither anti-A nor anti-B antibodies
• Type AB is universal recipient
– Neither A nor B antigens
13.4 Adverse Effects of
Immune Responses
Blood Transfusions
13.4 Adverse Effects of
Immune Responses
• Rh System
– Rh+
– Rh-
Rh antigen is present on red blood cells
Rh antigen is absent on red blood cells
– Significant in Pregnancy
• If a Rh- mother is pregnant with Rh+ baby
• If baby’s cells leak into mother’s bloodstream, she forms antiRh antibodies
– Attack baby’s RBC’s- hemolytic disease of newborn (HDN)
– This can be prevented by giving the Rh- mother anti-Rh
immunoglobulins in an injection
– The injection must be given before the mother becomes
sensitized to produce her own antibodies
Hemolytic Disease of the Newborn
13.5 Disorders of the Immune System
• Autoimmune Disease
– Cytotoxic T-cells or antibodies attack a person’s own
cells
• Myasthenia gravis - muscle weakness
• Multiple sclerosis - neuromuscular disorder
• Immune Deficiencies
– Immune system is unable to protect the body from
disease
• Acquired immune deficiency syndrome
• Severe combined immunodeficiency syndrome (inherited)