Lymph Transport and Immunity
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Transcript Lymph Transport and Immunity
Lymph Transport
and Immunity
Lymphatic system
4 main functions
1.
Lymphatic capillaries
1.
2.
absorb excess tissue fluid and return to
bloodstream (homestasis)
In small intestines lacteals absorb fats
(lipoproteins) and take to bloodstream
3. production, maintenance, and distribution of
lymphocytes
4. Defend the body against pathogens
Lymphatic vessels
Simple squamous epithelium
Lymph – colorless liquid, mostly water, located inside
lymph vessels
2 lymphatic ducts
Thoracic duct – empties all lymph from below thorax
and left side of head and neck, largest
Right lymphatic duct – returns lymph form right arm
and right side of head and neck
Edema – swelling due to accumulation of tissue fluid
Lymphatic organs
Contain lymphocytes (B and T), produced in red bone
marrow and thymus
Red Bone Marrow – site of stem cells, produce blood
cells
In adults – in skull, sternum, ribs, clavicle, pelvis,
vertebral column, heads of femur, humerus
B cell production and maturation
Thymus – largest in children, shrinks as we age
Contains T-cells that migrate from RBM and mature
Thymosin - hormone
Secondary lymphatic organs
Lymph nodes – cleanse lymph
contains B cells and T cells
macrophages engulf debris and pathogens
Spleen – upper left side of abdomen
Filters blood, removes old and defective cells
Without, more susceptible to infections
Tonsils – lymphatic tissue in pharynx
Cleanse lymph
Peyer’s patches/vermiform appendix work in lymphatic system to help to fight pathogens in
intestinal tract
Nonspecific defense - automatic
Barrier to entry – skin, mucous membranes, ciliate
cells, good bacteria
Inflammatory response – redness, heat, swelling,
pain
Chronic inflammation precipitates various ills
Phagocytes and natural killer cells neutrophils, dendritic cells and macrophages,
release cytokines that stimulate other WBC’s
NK – granular lymphocytes, kill virus-infected cells
Protective proteins – complement and interferons
Form a membrane attack complex, warns non-infected
cells of possible attack
Specific defenses
B lymphocytes –
Give rise to plasma cells that produce
antibodies
Antibody-mediated immunity
Produced and mature in bone marrow
In lymph nodes and spleen
Recognize antigen and then undergo clonal
selection
Clonal expansion produces antibody-secreting
plasma cells as well as memory B cells
Antibodies – immunoglobulins (Igs)
Y shaped, 2 arms – light and heavy based on
polypeptide chain
Antigen binding sites, particular
Antigen-antibody reaction = complex, mark
antigen for destruction
5 different classes
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 protein
Cytotoxic T cells destroy non-self antigenbearing cells
Helper T cells secrete cytokines, which
control the immune response
Helper T cells are host for HIV
Overview of Immunity, p645
Research has found that invertebrates have
similar non-specific immunity defenses
Specific defense mechanisms may have only
evolved in vertebrates.
Induced Immunity
Active immunity – usually induced, long
lasting
Immunization – vaccines – substances that
contain an antigen that results in antibodies for
future protection (B and T memory cells)
Passive immunity – short lived
given prepared antibodies to combat a
disease
Mother/placenta, Breast feeding, antivenom
Cytokines
Signaling molecules produced by
lymphocytes
Regulate WBC formation and function
Interferons and interleukins – used as
immunotherapeutic drugs
All may be used to enhance body’s ability to
recover form disease.
Monoclonal antibodies
Produced by the same plasma cells (B cells)
All antibodies are the same type
Various functions, used in pregnancy tests
and to detect infections
Immunity Side Effects
Allergies – hypersensitivities to substances
Tissue rejection – antibodies and cytotoxic T cells
bring about destruction of foreign tissues
Must take immunosuppressive drugs
Autoimmune diseases – Cytotoxic T cells or
antibodies mistakenly attack the body’s own cells as
if they bear foreign antigens
Myasthenia gravis, multiple sclerosis
Incompatible blood type – ABO blood system,
antigen on RBC’s and antibody in plasma