The Lymphatic System

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The Lymphatic System
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Non-Specific Defenses

• Physical Barriers
• Epithelium, hair, secretions, acid, enzymes
• Phagocytes
• 1st line of cellular defense removes debris and
  pathogens
• Microphages leave blood stream and enter
  peripheral tissues (neutrophils and eosinophils)
• Macrophages sensitive to chems in surrounding
  fluids can be free or fixed
• Interferons
• Slow spread of viral infections
• Stimulate macrophages and NK cells
• Inflammation
• Initiated by mast cells releasing histamines and
  heparin
• Local swelling, heat, redness, and pain
• Slows spread of pathogens
• Necrosis tissue destruction via lysosomes
• Pus accumulation of dead cells and debris
  (abscess accumulation of pus)
• Fever (gt98oF)
• Pyrogens proteins reset body's thermostat
• Incr. rate of metabolism
• Over 104oF damages CNS, nausea, hallucination,
  and convulsions

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Organization

• Lymph Vessels
• Begin at peripheral tissue? venous system
• Small valves prevent backflow
• Lymph Fluid
• Blood plasma but w/less proteins
• Lymphocytes
• Cells defend body
• 80 last 4 yearssome last 20 years or more!
• Lymph Tissue
• Loose connective tissue
• Tonsils, Appendix, Peyers Patches
• Size can increase or decrease depending on number
  of lymphocytes
• Lymph Organs
• Lymph nodes
• Spleen
• Thymus

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Lymph Vessels

• Lead towards trunk of body and empty into 2 ducts
• Thoracic duct lower abdomen, pelvis, lower
  limbs, left head, neck, and chest
• Right lymphatic duct right side of body, above
  diaphragm
• Lymphodema (edema) blockage of lymph drain

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Functions

• Protect body from pathogens
• Production, maintenance, and distribution of
  lymphocytes
• Return fluid from peripheral tissues to blood
• Distribute hormones, nutrients, and waste to
  general circulation

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Lymphoid Organs

• Lymph Nodes
• Filter and purify lymph before enters venous
  system
• Detects and removes antigens
• Stimulates T cells and B cells initiating immune
  response
• Lymphomas cancer arising from lymphocytes
• Thymus
• Decrease in size after puberty
• T cell production and maturation
• Spleen
• 5 long on left side, deep red
• Filters blood, removes abnormal blood cells and
  initiates B cell and T cell responses to antigens
• Macrophages identify and engulf damaged or
  infected cells

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Lymphocytes

• 25 of circulating wbc
• T cells thymus dependent (80 circulating
  lymphocytes)
• Cytotoxic T cells attack foreign cells or body
  cells infected w/ virus
• Helper T cells stimulate T cells and B cells
• Suppressor T cells inhibit T cells and B cells
• B cells -bone marrow derived (10-15 circ.
  Lymphocytes)
• Plasma cells secrete antibodies
  (immunoglobulins)
• Antibodies bind to antigens
• NK cells natural killer cells (5-10 circulating
  lymphocytes)
• Attack foreign cells, viral infected cells, and
  cancer cells

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Specific Defenses

• Immunity respond to the presence of specific
  antigens
• Antigens non-self substance that excites the
  immune system and stimulates a response
• Genes determine specificity
• T cells cell mediated immunity
• Defend against abnormal cells
• Pathogens inside of cells
• B cells antibody-mediated immunity
• Defend against antigens and pathogens in body
  fluids
• Antibodies (immunoglobulins) bind to specific
  antigen, Y shape with 2 antigen binding sites

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Immune Response (antibody mediated)

• B cell binds w/antigenbecomes activated and
  produces clones
• B cell clones
• Plasma cells secrete antibodies (2,000 per
  sec!) reaches peak 10 days
• Memory B cells continue to circulate, and can
  speed process to 2-3 days if recognizes an old
  enemy

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Immune Response (cell mediated)

• T cells cannot bind to free antigen
• Macrophages and B cells must present antigen to T
  cells
• Once T cell binds to presented antigen
• Killer (cytotoxic) T cells
• Binds to target cell and inserts a toxic chem
  target cell ruptures
• Helper T cells
• Recruit other cells to fight invaders
• Stimulates B cells to increase production of
  antibodies
• Simulates Killer T cells to multiply
• Suppressor T cells
• Release chems to suppress B and T cell activity
• Most T cells enlisted to fight die w/in a few
  days
• Some remain as memory cells to respond quickly to
  subsequent invasions

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Properties of Immunity

• Specificity
• T cells and B cells target one specific antigen
• Versatility
• Millions different lymphocytes w/diff antigen
  receptors
• Memory
• 1st exposure lymphocytes divide to create
  attack cells and memory cells
• Response to 2o exposure to antigen is stronger
  than 1st
• Tolerance
• Doesnt respond to normal self tissues or
  antigens

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Types of Immunity

• Innate genetically determined
• Acquired arises during life
• Active appears after exposure to antigen
• Naturally- continually induced as encounter new
  pathogens or antigens
• Induced stimulated under controlled conditions
• Vaccine dead/inactive pathogen that induces an
  immune response
• Passive transfer of antibodies from another
  source
• Naturally mother to baby
• Gestation via placenta
• Infancy via breast milk
• Induced antibodies administered to fight
  infection or prevent disease after exposure

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Lymphatic Project

• Cartoon/comic strip analogous to lymphatic system
  that highlights functions of B cells, plasma
  cells, antibodies, and memory B cells, Helper
  Tcells, Killer T cells, and suppressor T cells
• Research and write an essay on allergies, organ
  transplant and rejection, multiple sclerosis,
  systemic lupus, OR HIV/AIDS