Cells and tissues of the immune system S1M2

  1. What is lymphoid tissue
    It is a type of connective tissue characterized by its rich supply of lymphocytes
  2. What is the support system in lymphoid tissue
    Reticular fibrils
  3. What are the reticular fibers made from
    Fibroblasts called reticular cells
  4. Reticular cells, and therefore fibroblasts are derived from what embryonic tissue
  5. The epithelial cells are derived from what embryonic tissue
  6. When lymphoid tissue is encapsulated by connective tissue it is called
    A lymphoid organ (Lympth nodes)
  7. What is a lymphoid nodule
    A bundle of lymphoid cells found in connective tissue
  8. What is the importance of Mucosa-associated lymphoid tissue (MALT), and where can it be found
    It forms a protective barrier (GI, respiratory, reproductive, urinary)
  9. What is the main distinction between primary and secondary lymphoid nodules
    Secondary lymphoid nodules have activated B cells
  10. Primary lymphoid nodules are absent of
    Plasma cells and a germinal center
  11. Primary lymphoid nodules contain
    B Lymphocytes both naive, and B memory cells
  12. Secondary lymphoid nodules contain what cells that primary nodules lack
    • APC's
    • Activated B cells
    • Germinal centers
    • Plasma Cells
    • Follicular Dendritic cells
  13. How is the germinal center formed in the secondary nodules
    APC's activate the B cells and they proliferate forming the germinal center
  14. Follicular dendritic cells differ from traditional dendritic cells in that
    They do not act as antigen presenting cells because they do not contain Class II markers
  15. Follicular Dendritic cells perform what role
    They help activate B cells
  16. MALT contains a lot of what cells
    • B cells
    • Helper T cells
    • Macrophages
    • Plasma cells
    • APC's
    • Lymphoid nodules
  17. What is a Peyers patch
    This is a aggregation of lymphoid nodules in the Ileum
  18. What are the primary lymphoid organs and why
    Thymus and bone marrow, these are the locations that the B and T cells become immunocompetent
  19. What are the secondary lymphoid organs and why
    • Spleen
    • Lymph nodes
    • Tonsils....
    • This is where the immunocompetent cells migrate for action
  20. Palatine tonsils are located where and have what features
    • They are located in the roof of the mouth on the two sides just before the esophagus.
    • They are incompletely encapsulated by stratified squamous non-keratinized epithelium containing 10-20 crypts
  21. Ligual tonsils are located where
    Dorsal surface of the posterior 1/3 of the tongue, and have a single crypt
  22. Thymus is made up of what cells
    • T cells
    • macrophages
    • epithelial cells
    • reticular cells
    • No B cells
  23. Hassells corpuscles are found only in
    The medulla of the thymus, function is unknown
  24. The thymus has what two primary zones in its lobules
    Medulla and Cortex
  25. The medulla of the thymus contains what cells
    • T cells
    • Epithelial reticular cells
    • Macrophages
    • Hassall corpuscles
  26. What is unique about the capillaries in the thymus
    They are non-fenestrated (no openings), and have a thick basal lamina making them impermeable to proteins and circulating antigens
  27. Which part of the thymus contains the T cell precursors
    The cortex
  28. When does the thymus reach its greatest size
    At puberty, then it shrinks
  29. What is an additional cell found in the thymus to help with its function in the immune system
    Nurse cells that assist T cells in their development
  30. What happens to T cells in the thymus cortex
    They divide by mitosis, presented to self antigens bound to class I and II MHC molecules.
  31. What is unique about the T cells precursor cells in the thymus
    Only 5% of them survive and migrate to the medulla
  32. What happens to T cells in the medulla of the Thymus
    They mature and then are distributed to the rest of the body
  33. What are the four hormones in the epithelial cells of the thymus that are required for proper T cell maturation
    • Thymosin
    • Thymopoietin
    • Thymulin
    • Thymic humoral factor
  34. What is DiGeorges syndrome
    • Congenital Thymic aplasia
    • There is abnormal cell mediated immunity, but normal humoral immunity
    • Patients have a unique facial structure
  35. What is the function of the lymph nodes
    They are filters of the circulatory system
  36. What are the primary layers of a lymph node and their contents
    • Capsule
    • Subcapsular sinus
    • Superficial cortex - B cells
    • Paracortex - T cells
    • Medulla - Plasma cells
  37. All of the lymph in tissue must pass through
    At least one lymph node before entering the blood stream
  38. What portion of the lymph nodes has high endothelial vessels
    The inner or paracortex
  39. In the lymph nodes the B cells and T cells go to what differing areas
    • B cells to the cortex
    • T cells to the paracortex
  40. The high endothelial vessels in the paracortex of the lymph nodes are lined by what cells
    Simple cuboidal cells
  41. What is the route of blood in the lymph nodes
    Artery - Hilum of node - cortical capillaries surrounding lymph nodules - high endothelial vessels (Post capillary venules)
  42. What is Hodgkin Disease
    Painless progressive enlargement of lymph nodes, liver, spleen, fever, anemia, and weight lose
  43. What is the largest lymphoid organ
  44. What is the primary job of the spleen
    • To filter the blood and remove worn out RBC's, phagocytes, as well as mount immune responses.
    • It is also a production site of activated lymphocytes
  45. What are the two major components of the pulp on the spleen
    • White
    • Red
  46. What does the white pulp contain
    PALS (periarterial lymphatic sheath) made of T cells, and lymphoid nudules
  47. When the splenic artery enters the spleen what is the path it undergoes
    • Trabecular arteries
    • Central artery (encapsulated by PALS)
    • Pass the marginal zone
    • Enter red pulp
    • Leave Trabecular vein
  48. What is the purpose of the marginal zone in the Spleen
    Plays an important role in immunological activities in that it contains many blood antigens
  49. What does the germinal center of lymphoid nodules contain a lot of
    B Cells
  50. What are the two main components of the red pulp of the spleen
    • Splenic cords (Dense lymphoid tissue)
    • Sinusoids (irregular blood vessels)
  51. Splenic sinuses have what important feature for movement of blood
    Lots of openings
  52. What is the difference between a closed system and an open system
    The blood in a closed system always remains in the vessels, in an open system the blood opens to the splenic cords and passes through the cells to reach the sinusoids
  53. Class switching of immunoglobulins primarily happens where
    Germinal center of lymphatic nodules
  54. Dendritic cells are only found where in the lymph nodes
    Outer cortex
  55. Cytotoxic T cells kill target cells via
    Lysing them with perforins and fragmentins
  56. Immunocompetent T cells migrate where in the thymus
    To the pariarterial lymphatic sheath
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Cells and tissues of the immune system S1M2