Chapter 14: Lymphatic System and Immunity

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Chapter 14 Lymphatic System and Immunity
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Structure of the Lymphatic System

• Lymphatic system drains excess fluid from tissues
  and fluid that escapes the blood vessels
• Three components
• Lymphatic vessels
• Lymphatic capillaries
• Lymph nodes

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Structure of Lymphatic System

• Lymph vessels
• Similar to veins but thinner
• Valves
• Vessels merge to join with lymphatic trunks
  larger vessels
• Lymph capillaries
• Closed ended tubes extend into the tissues

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Structure of the Lymphatic System

• Lymph nodes
• Contain large numbers of macrophages and
  lymphocytes
• Hilum is where lymph vessels enter
• Capsule cover each nodule to break it up into
  compartments called nodules

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Location of Lymph Nodes
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Lymph Movement

• Lymph movement requires
• Hydrostatic pressure
• Muscle contraction
• Smooth muscle contraction in the larger lymph
  vessels
• Pressure changes due to breathing

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Filarial worm and Elephantiasis

• Filarial worms are parasites that can block the
  flow of lymph
• This can cause fluid build which can turn into
  enlarged body parts

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Thymus

• Found superior to the heart
• Large during infancy and decreases to scar tissue
  as you grow
• Produces T lymphocytes
• Produces thymosin hormone which stimulate the T
  cells to mature

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Spleen

• Largest lymphatic organ
• Inferior to diaphragm
• Filter blood instead of lymph
• Parts of the spleen
• Red Pulp
• Numerous red blood cells
• Lymphocytes and macrophages break down old or
  damaged RBCs
• White Pulp
• Contains lymphocytes in each of the nodules

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Immunity Non Specific Defenses

• Non-specific defenses are defenses that are
  general in nature and can protect against a
  variety of pathogens
• First lines of Defense
• Skin Keeps pathogens out
• Sweat, tears and Mucus protect pathogens from
  entering the body
• Cilia traps dust and other particles in from
  blocking passageways
• Lysozyme is produced by skin to break down
  Bacterial cell wall

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Immune System Nonspecific Defenses

• Second Line of Defense
• Inflammatory Response
• Site is injured and cells release chemicals that
  attract macrophages
• Capillaries dilate and fluid flows into affected
  area causing swelling and redness
• Macrophages arrive and clean up bacteria or other
  particles
• Pus and clots can form at the site
• Most active cells at site are monocytes and
  neurtophils

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Immune System Non Specific Defenses

• Chemical Barriers
• Digestive Juices and enzymes
• Interferon hormone like polypeptide chains that
  signal a virus has invaded or tumor cell.
• Interferes with viral replication
• Stimulates phagocytosis
• Helps protect from further infection

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Immune System Specific Defenses

• Third line of Defense
• Resistance to specific pathogens or their toxins
• Antigens proteins, polysaccharides, or
  glycoproteins located on cell membranes
• Before birth your body begins to recognize self
  vs non self by having specific receptors on
  B-cells and T-cells
• Haptens small molecule that can combine with
  other molecules to stimulate an immune response
  (dust and Penicillium)

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Immune System Types of Cells

• B-Cells
• Develop in the bone marrow
• Mostly found in the spleen, lymph nodes, bone
  marrow, and intestinal lining
• Memory B cells remember diseases
• Plasma cell secrete antibodies

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Immune System Type of Cells

• T-Cells (Named for Thymus)
• Killer T cells (cytotoxic T cells) attack
  antigens with toxins
• Helper T cells release cytokines when activated
• Memory T cells when activated by antigen
  convert into Killer T cells
• Develop in the thymus

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Immune System Types of Cells

• Mast Cells
• Release Heparin and histamine which promote
  inflammatory response

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Immune System Specific Defense (Cell mediated
Immunity)
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Cell Mediated Immunity

• T cells attach to foreign particles, cells
  displaying antigens or bacteria . (cell to cell
  contact)
• T cells also produce chemicals that will activate
  Killer T cells (cytotoxic T-cells) and can cause
  B-cells to mature.

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Immune System Specific Defenses (humoral
immunity)
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Humoral Immunity

• Use of Antibodies to eliminate disease
• Antibodies can bind to antigens
• Several antibodies can cluster around an
  antigen(s), so macrophage to find it easier and
  engulf it.
• This can lead to future protection from an
  infection

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Aquired Immunity

• Naturally Aquired Immunity
• Passive Antibodies pass from Mom to Fetus Short
  term immunity with stimulating immune response
• Active Getting the disease symptom of disease
  and stimulation of immune response
• Artifically Aquired Immunity
• Passive Injection of Anti-serum short term
  immunity without stimulating an immune response
• Active Vaccination stimulate immune response
  without severe reaction

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Allergies

• Immune response stimulated by a nonharmful
  substance.
• Antigens Allergens
• This stimulates production of histamine by mast
  cells and antigen antibody reactions.

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Tissue Rejections

• Person receiving a transplanted organ or tissue
  has a severe reaction because their body
  recognizes the tissues as non-self.
• Immunosuppressive Drugs reduce rejection of
  transplanted tissues.

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Autoimmune Diseases

• Rhumatoid Arthritis Bodies immune system begins
  attacking joints disfiguring them.
• Strep bacteria can cause the body to attack heart
  valves
• Lupus immune disease in which the immune system
  become hyperactive and starts attacking body
  tissues