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14.1 (pathogens: various microorganisms that cause disease in humans…

- - - - white pulp- lymph-nodes arranged around central arteries
      - red pulp- blood filled sinuses
    - - removal and destruction of foreign particles and worn blood cells from blood, macrophages remove and destroy bacteria and damaged or worn red blood cells and platelets through phagocytosis
      - stores and releases blood during hemorrhage
      - in immunity as a site of B cells proliferation into plasma cells
- - - - lymph nodes are located along lymphatic pathways contain lymphocytes an macrophages, which destroy invading microorganisms
      - size is usually less that 2.5 cm and shape is bean-like, with blood vessels, nerves, and efferent lymphatic vessels attached to the indented region - hilum
        
        afferent lymphatic vessels enter at points on the convex surface
      - node is enclosed in a scene CT capsule that tends into the node and subdivides into nodules
      - outer region= cortex, contains germinal centers of densely packed B cells in spaces called lymphatic nodules or follicles
      - inner region=medulla, contains T cells arranged as medullary cords
      - c. location of lymph nodes
        
        lymph nodes are generally occurring in groups or chains along the paths of larger lymph vessels
        
        they occur primarily in the following regions:
        
        cervical, axillary, inguinal
        
        they also occur within the following body cavities
        
        pelvic, abdominal, thoracic
    - - one way direction, lymph enters the node through one of several afferent lymphatic vessels on convex surface, flows inward through the sinuses and exits the node via one of two efferent via one of two efferent lymphatic vessels at hilum
    - - removal and destruction of potentially harmful foreign particles from lymph
        
        accomplished through phagocytosis by macrophages, centers for the production of lymphocytes that act against foreign particled
- - - - cytoxic T cells - cell-mediated immunity
      - helper T cells stimulate both T and B cells
      - suppressor T cells inhibit both T and B cells
    - - differentiate into plasma cells - produce
      - immunoglobulins : - antibodies - bind to antigens
      - antibody- antigen complex
        
        antibody - mediated immunity (humoral immunity)
        
        antibodies in body fluids
    - - attack foreign cells, virus infected cells and cancer cells
      - immunological surveilance
- - - - NK cells
        a. special lymphocytes
        b. attack foreign material
        c. microbes, cancer cells, other abnormal cells
        d. use perforins to rupture cell membranes
        e. enhance inflammation
      - inferons
        a. small antiviral proteins
        b. release by activated lymphocytes, macrophages & infected cells
        c. increase resistance to viral infection
        d. slows the spread of the disease
      - complement system
        a. 11 special complement proteins
        b. attract phagocytes
        c. stimulate phagocytosis
        d. destroy plasma membranes
        e. promote inflammation
      - inflammation
        a. inflammation is a tissue response to damage, injury, or infection
        b. blood vessels dilate, increasing capillary permeability; the response includes localized tissue swelling, redness, heat and pain
      - fever
        a. infection causes some lymphocytes to produce Interleukin I, which increases body temperature
        b. other factors can also increase body temperature, including exposure to heat, UV light, acids, and bases
        c. increased body temp. decreases blood iron levels, which increases phagocytic activity