Anatomy lymphatic system

• Lymphatic system


  Several structures and organs that contain lymphatic tissue, bone marrow, and a fluid called lymph that flows within lymphatic vessels and plays an integral role in immunity
• Formation and Flow of Lymph

  1. Interstitial fluid

  2. Lymph capillaries

  3. Lymph vessels

  4. Lymph trunks

  5. Lymph ducts

  6. Subclavian veins
• Lymphatic capillaries


  • Closed on one end
  • Located between cells of many tissues
  • Merge to form lymphatic vessels
  • Thin walls and many valves
  • Lymph flow is slow to sluggish, assisted by muscle and respiratory pumps
• Lymph trunks


  Include the lumbar, intestinal, bronchomediastinal, subclavian, and jugular trunks
• Lymph trunks


  Merge to form either the thoracic duct or the right lymphatic duct
• All cells with the exception of red cells and platelets are white blood cells or leukocytes and are all part of our immune system
• Natural Killer (NK) cells

  A type of white blood cell that engulfs and digests cellular debris, foreign substances, microbes, cancer cells, and anything else that does not have the types of proteins specific of healthy body cells on its surface in a process called phagocytosis
• Macrophages


  Large phagocytes found in essentially all tissues, where they patrol for potential pathogens. Besides phagocytosis, they play a critical role in nonspecific defense (innate immunity) and also help initiate specific defense mechanisms (adaptive immunity) by recruiting other immune cells such as lymphocytes
• Plasma cells


  White blood cells that secrete large volumes of antibodies, transported by the blood plasma and the lymphatic system
• Primary lymphatic organs


  • Organs where immune cells become immunocompetent - mature and are capable of mounting an immune defense
  • Red bone marrow
  • Thymus - T cells or T lymphocytes mature
• Thymus


  An organ where T cells or T lymphocytes mature
• Secondary lymphatic organs and tissues

  • Lymph nodes - major sites of B, T, and other immune cells, important for the proper functioning of the immune system, acting as filters for foreign particles and cancer cells
  • Spleen - a number of functions including filter blood like lymph nodes, producing antibodies and removing worn out blood cells, e.g. RBC
  • Lymphatic nodules - masses of lymphatic tissue scattered throughout the mucous membrane of the small intestine
• Lymphatic nodules


  Masses of lymphatic tissue that are not surrounded by a capsule, scattered throughout the lamina propria of mucous membranes lining the gastrointestinal, urinary, and reproductive tracts and the respiratory airways, also referred to as mucosa-associated lymphatic tissue (MALT)
• The body system that carries out immune responses is the lymphatic system
• Nonspecific Resistance (Innate Immunity)


  Present at birth and includes defense mechanisms that provide general protection against invasion by a wide range of pathogens
• Specific Immunity (Adaptive Immunity)

  Involves activation of specific lymphocytes that combat a particular pathogen or other foreign substance
• Internal Defenses of Innate Immunity

  • Antimicrobial proteins
  • Phagocytes
  • Natural killer cells
  • Inflammation
  • Fever
• Chemotaxis


  A chemically stimulated movement of phagocytes to a site of damage
• Mechanical defenses


  • Skin, mucous membranes, tears, saliva, mucus, cilia, epiglottis, urine flow, defecating, vomiting
• Chemical defenses


  • Sebum, lysozyme, gastric juice, vaginal secretions
• Inflammation


  A normal immune response
• Adaptive Immunity


  Involves the production of specific types of cells or specific antibodies to destroy a particular antigen. An antigen is any substance (foods, microbes, drugs, pollen, etc.) that the immune system recognizes as foreign (nonself). Adaptive immunity involves lymphocytes called B cells and T cells.
• Cell-mediated immunity


  Cytotoxic T cells directly attack invading antigens
• Antibody-mediated immunity


  B cells transform into plasma cells, then produce antibodies
• Immunological memory


  Due to the presence of long-lasting antibodies and very long-lived lymphocytes that arise during division and differentiation of antigen-stimulated B cells and T cells
• Immunization


  Against certain microbes is possible because memory B cells and memory T cells remain after a primary response to an antigen, providing immunological memory. The secondary response provides protection should the same microbe enter the body again.
• With advancing age, most people become more susceptible to all types of infections and malignancies. Their response to vaccines is decreased, and they tend to produce more autoantibodies (antibodies against their body's own molecules). T cells and B cells are less responsive with age.