Lymph Transport and Immunity

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Lymph Transport and Immunity
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Lymphatic system

• 4 main functions
• Lymphatic capillaries
• 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

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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

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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

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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
• Peyers patches/vermiform appendix -
• work in lymphatic system to help to fight
  pathogens in intestinal tract

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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 WBCs
• NK granular lymphocytes, kill virus-infected
  cells
• Protective proteins complement and interferons
• Form a membrane attack complex, warns
  non-infected cells of possible attack

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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

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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

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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
  antigen-bearing cells
• Helper T cells secrete cytokines, which control
  the immune response
• Helper T cells are host for HIV

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Overview of Immunity, p645

• Research has found that invertebrates have
  similar non-specific immunity defenses
• Specific defense mechanisms may have only evolved
  in vertebrates.

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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

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Cytokines

• Signaling molecules produced by lymphocytes
• Regulate WBC formation and function
• Interferons and interleukins used as
  immunotherapeutic drugs
• All may be used to enhance bodys ability to
  recover form disease.

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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

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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 bodys own cells
  as if they bear foreign antigens
• Myasthenia gravis, multiple sclerosis
• Incompatible blood type ABO blood system,
  antigen on RBCs and antibody in plasma