Lymphatic system

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Lymphatic system
2013-04-02 22:05:52

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  1. Lymphatic System
    • Includes the cells, tissues, and organs responsible for defending the body
    • Lymphocytes are the primary cells of the lymphatic system

    The ability to resist infection and disease is immunity
  2. Lymphatic system consists of:

    • _Lymph__ – fluid that is similar to blood plasma but has a lower concentration of proteins
    • A network of lymphatic vessels (called lymphatics) that connect to veins
    • Lymphoid tissues and lymphoid organs throughout the body
    • Lymphocytes
  3. Function of lymphatic system is to
    produce, maintain, and distribute lymphocytes throughout the body
  4. Lymphatic vessels:
    Lymphatic capillaries 
    &how do they differ from blood capillaries??
    Lymphatic vessels:

    Lymphatic capillaries – branch throughout the peripheral tissues

    Differ from blood capillaries:

    a.)Originate as pockets rather than continuous tubes

    b.)They have thinner walls than capillaries

    c.)Have larger diameters

    Endothelial cells not tightly bound together but they do overlap and only allow fluids to enter the capillaries, not exit
  5. lymph vessels
    From the lymphatic capillaries, lymph flows
    From the lymphatic capillaries, lymph flows into larger lymphatic vessels that lead towards the body’s trunk
  6. 2 sets of lymphatic vessels collect lymph from the lymphatic capillaries:
    Superficial lymphatics
    Deep lymphatics
    • superficial
    • Located in the skin

    Deep lymphatics

    Larger lymphatic vessels that are around skeletal muscles and organs
  7. what are lymphatic trunks?
    what duct drains the majority of the body?
    Superficial and deep lymphatics converge to form larger vessels called lymphatic trunks

    • Trunks enter into 2 large collecting vessels: Thoracic duct and right lymphatic duct
    • Thoracic duct drains the majority of the body
  8. Lymphocytes 

    3 classes:
    t cells, b cells, nk cells
  9. T cells (thymus-dependent)
    • Most lymphocytes are T cells
    • T cells involved in the production of cell-mediated immunity
  10. B cells (bone-marrow derived)
    • B cells differentiate into plasma proteins that secrete antibodies
    • B cells are responsible for antibody-mediated immunity
  11. NK cells (natural killer cells)
    • NK cells attack foreign cells, normal cells infected with viruses, and cancer cells that appear in normal tissues
    • NK cells responsible for immunological surveillance
  12. Lymphocytes have relatively long life spans: ~4-20 years

    Lymphocytes move throughout the body, into and out of the tissues and blood vessels and lymphatic vessels

    Which cell type moves the quickest?
    T cells are quicker (more common) than B cells
  13. Lymphocyte production (lymphopoiesis)
    Red bone marrow maintains normal lymphocyte levels
    2 classes of lymphoid stem cells: 1
    1 stays in the __bone marrow__

    Produces B cells and NK cells

    • B cells move into lymphatic tissues
    • NK cells are continually migrating
  14. 2nd class of lymphoid stem cell
    1 migrates to the _thymus__

    Where T cells mature

    Once T cells are mature, they enter blood and migrate to red bone marrow and other lymphatic tissues

    T cells isolated once they are in the thymus by the blood-thymus barrier
  15. Lymphoid Tissues
    Lymphoid tissues are connective tissues dominated by lymphocytes

    A lymphoid nodule occurs when there lymphocytes densely packed in an area of areolar tissue

    Tonsils are large lymphoid nodules in the walls of the pharynx (throat)
  16. Lymphoid Organs 
    Lymph nodes 
    • Small lymphoid organs scattered throughout the body
    • Greatest number in the neck, armpits, and groin

    Shaped like a kidney bean
  17. whats is hilum?
    Blood vessels and nerves enter/exit lymph node at shallow indentation called ______hilum__________________
  18. Afferent lymphatics
    Afferent lymphatics bring lymph to the lymph node from peripheral tissues
  19. Efferent lymphatics
    carry lymph from the lymph node to the peripheral circulation
  20. Flow of lymph in the lymph node
    Enters the subcapsular space from the afferent lymphatic

    Then flows through the outer cortex of the node:outer cortex contains B cells 

    Next, lymph passes through lymph sinuses in the deep cortex: Deep cortex contains T cells

    Lymph next travels through the medulla (core) of the lymph node: Medulla contains B cells

    After medulla, lymph enters the __efferent lymphatic_ to leave the node
  21. Lymph nodes function as filters 
    – they remove foreign antigens that pass through the nodes
  22. Lymph organ

    Pink grainy organ located in the mediastinum, just posterior to the sternum

    Much larger in newborns and infants

    Gets smaller after puberty
  23. thymus
    Contains an outer cortex and inner medulla
    • T cells in the cortex are actively dividing
    • T cells migrate into the medulla as they mature
  24. thymus
    T cells in the cortex are arranged in clusters
    Clusters surrounded by reticular epithelial cells which form the blood-thymus barrier
  25. thymus
    _Medulla __ does not have a blood-thymus barrier

    T cells in the medulla can pass to or from the blood stream through the walls of blood vessels in the medulla (or into efferent lymphatics)
    Reticular epithelial cells are still present and cluster together to form distinctive structures called Hassall’s corpuscles
  26. Spleen 
    Contains the largest collection of lymphoid tissue in the body
    Primary functions of spleen
    1.)Removing abnormal blood cells

    2.) Storing iron recycled form RBC

    3.)Initiating immune responses by B and T cells in response to antigens
  27. spleen is located where?
    The spleen is located in the upper left region of the abdominal cavity

    In contact with the diaphragm, stomach, and left kidney
  28. spleen pulp?
    Inside the spleen the cellular components are referred to as pulp

    • Red pulp contains RBCs
    • White pulp is lymphatic

    Lymphocytes are scattered throughout the red and white pulp, and any foreign particle is quickly recognized by lymphocytes

    Macrophages are also present
  29. Innate (nonspecific)
    Prevent the approach, deny the entry, or limit the spread of microorganisms or other environmental hazards
  30. Innate (nonspecific)
    Physical barriers
    Your skin, in addition to the linings of your digestive, respiratory, urinary, and reproductive tracts defend against foreign materials
  31. Innate (nonspecific)

    1st line of defense against foreign invasion

    neutrophils & eosinophils
  32. Innate (nonspecific)
    large, much more active phagocytic cells

    • Derived from monocytes
    • Can be either fixed in a tissue (fixed macrophage) or freely mobile throughout the body (free macrophage)

    Fixed macrophages can become mobile during an infection
  33. Innate (nonspecific)
    Phagocytes can move through capillary walls by squeezing through adjacent cells

    Phagocytes are attracted or repelled by chemicals in the surrounding fluids
  34. Innate (nonspecific)
    Phagocytosis begins with
    adhesion of the phagocyte to the target

    Vesicle then forms around entire target – lysosome or peroxisome degrades target
  35. Innate (nonspecific)
    Immunological surveillance
    Natural killer cells are responsible for recognizing and destroying normal body cells when they become abnormal

    NK cells recognize abnormal antigens on the plasma membrane
  36. Innate (nonspecific)
    immunological surveillance
    NK cell activation
    • 1.)NK cell first recognizes and attaches to the target cell
    • 2.)The Golgi apparatus of the NK cell moves to face directly at the abnormal cell

    • 3.)Golgi apparatus produces a flood of secretory vesicles that contain the proteins called perforins
    • 4.)Perforins are releases and cause the formation of __pores in the abnormal cell which will kill the cell
  37. Innate (nonspecific)
    Interferons are small proteins released by activated lymphocytes and macrophages, and by tissue cells infected with viruses

    Interferons cause a normal cell to produce antiviral proteins that help protect the cell
  38. Innate (nonspecific)
    Complement system
    Your body’s plasma contains 11 special complement proteins that interact with one another in a cascade of reactions to ‘complement’ the actions of antibodies

    Helps destroy antigens by forming pores in the infected cells and increasing phagocytosis
  39. Innate (nonspecific)
    Inflammatory response
  40. Inflammation is a localized tissue response to injury
    Produces local swelling, redness, heat, and pain
  41. Innate (nonspecific)
    Inflammatory response

    Inflammation has several effects:
    • 1.)Injury is temporarily repaired
    • 2.)Additional pathogens are prevented from entering wound
    • 3.)Spread of pathogens away from injury is slowed
    • 4.)Other immune defenses are activated
  42. Innate (nonspecific)
    cells response to injury
    1.)Mast cells are activated by injury and release histamine, heparin, and prostaglandins into the environment surrounding the cell

    2.)Increased blood flow raises local temperature which accelerates activity of phagocytes

    3)Blood vessel permeability increases – clotting and complement factors can enter the injured area

    4)Neutrophils are drawn to area by chemotaxis

    5)Fixed and free macrophages engulf pathogens and cell debris

    6.)Active phagocytes release proteins known as cytokines which stimulate local cells to repair the damaged tissue
  43. Innate (nonspecific)
    • Body temperature greater than 99°F (37.2°C)
    • Fevers can be beneficial, within certain limits
    • High body temperatures may inhibit some viruses and bacteria
    • Also, higher body temperatures can increase body metabolism
  44. Adaptive (specific) Defense 
    • Adaptive defenses result from the coordinated activities of T cells and B cells
    • T cells bring about cell-mediated immunity and B cells provide antibody-mediated immunity
  45. Role of T cells in the immune response4 major types of T cells:
    Cytotoxic T
    cells are enter peripheral tissues and directly attack antigens
  46. Role of T cells in the immune response4 major types of T cells:
    memory t cells
    Memory T cells respond to antigens that they have encountered by cloning more lymphocytes to fight off future pathogens
  47. Role of T cells in the immune response4 major types of T cells:
    helper T cells 
    stimulate responses of T and B cells
  48. Role of T cells in the immune response
    4 major types of T cells:

    supressor t cells
    inhibit T and B cells
  49. Role of T cells in the immune response
    Antigen Presentation 
    T cells need to recognize an antigen bound to glycoproteins on the plasma membrane of another cell

    These glycoproteins are referred to as majory histocompatibilty complex (MHC) proteins
  50. Role of T cells in the immune response
    Antigen Presentation
    MHC Class I proteins are on the plasma membrane of all nucleated cells in the body
    T cells recognize MHC Class I proteins and ignore these cells – signals that cell is healthy

    If the cell is not healthy, the abnormal proteins are displayed by the Class I MHC proteins on the cell’s surface

    The presence of the abnormal protein signals that cell needs to be destroyed
  51. Role of T cells in the immune response
    Antigen Presentation

    MHC Class II cells are present on the plasma membrane of antigen-presenting cells (APCs)
    Antigen presenting cells are responsible for activating T cell defenses against foreign cells

    All the phagocytes are antigen-presenting cells

    Phagocytic APCs engulf and break down the foreign pathogens and then the Class II MHC molecules are bound to the plasma membrane

    Class II MHC proteins appear on the plasma membrane only when the cell is processing antigens
  52. Role of T cells in the immune response
    Antigen Recognition
    • Inactive T cells have receptors for either Class I or Class II MHC proteins
    • When a T cell detects its appropriate antigen, the T cell is activated

    The markers on the T cells that respond to the antigens are called CD markers
  53. Role of T cells in the immune response
    Antigen Recognition
    CD 8 markers are found on cytotoxic, memory, and suppressor T cells

    Respond to antigens presented by Class I MHC proteins

    Cytotoxic T cells will seek out and destroy the cell with the specific antigen

    Memory T cells will ‘remember’ the antigen so if it comes along again they will produce cytotoxic T cells to destroy that cell

    Suppressor T cells will eventually suppress the immune response
  54. Role of T cells in the immune response
    Antigen Recognition
    CD4 markers are found on helper T cells
    • respond to class II mhc2
    • Helper T cells secrete cytokines that coordinate immune responses
  55. Role of B cells in the immune response
    • B cells produce specific antibodies
    • Each B cell carries its own particular antibody on the plasma membrane
  56. Role of B cells in the immune response

    When the particular B cell recognizes the appropriate antigen, it begins the process of activation – this process is called sensitization

    usually occurs in lymph nodes 
  57. 7 ways the antibody will cause elimination of the antigen
    Prevents the virus or toxin from attaching to a cell
  58. 7 ways the antibody will cause elimination of the antigen
    Precipitation and agglutination 
    Antibodies can link large numbers of antigens together and form clumps that prevent further damage
  59. 7 ways the antibody will cause elimination of the antigen
    Activation of complement system 
  60. 7 ways the antibody will cause elimination of the antigen
    attraction of phagocytes 
  61. 7 ways the antibody will cause elimination of the antigen
    Increased phagocytosis when the foreign particle is coated by antibodies and complement proteins
  62. 7 ways the antibody will cause elimination of the antigen
    stimulation of inflammation 
    Antibodies can produce inflammation by stimulating basophils and mast cells
  63. 7 ways the antibody will cause elimination of the antigen

    Prevention of bacterial and viral adhesion