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  • 1. Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Chapter 30 Lymph Transport and Immunity
  • 2. The Lymphatic System Functions in Transport and Immunity
  • 3. 30.1 Lymphatic vessels transport lymph
    • Lymphatic system is closely associated with the cardiovascular system
    • Has four main functions that contribute to homeostasis
      • Lymphatic capillaries absorb excess tissue fluid and return it to the bloodstream
      • In the small intestines, lymphatic capillaries called lacteals absorb fats in the form of lipoproteins and transport them to the bloodstream
      • The lymphatic system is responsible for the production, maintenance, and distribution of lymphocytes
      • The lymphatic system helps defend the body against pathogens
    • Lymphatic vessels form a one-way system that begins with lymphatic capillaries
      • Lymphatic capillaries take up excess tissue fluid, lymph
        • Lymph also contains defense molecules, antibodies , which are produced by lymphocytes
  • 4. Figure 30.1 The vessels and organs of the lymphatic system
  • 5. 30.2 Lymphatic organs defend the body
    • Red bone marrow - site of stem cells capable of producing lymphocytes
      • Become mature B cells, a major type of lymphocyte, in the bone marrow
    • Thymus gland - located in thoracic cavity between trachea and sternum
      • T cells, the other major type of lymphocyte, migrate from the bone marrow through the bloodstream to thymus, where they mature
    • Lymph nodes - small, ovoid structures occurring along lymphatic vessels
      • Located at body nodes, such as groin and armpits
      • Have many open spaces called sinuses
    • Spleen - located in upper left side of abdominal cavity posterior to stomach
      • Most of the spleen is red pulp that filters the blood
      • Red pulp consists of blood vessels and sinuses, where macrophages remove old and defective blood cells
    • Patches of lymphatic tissue in the body:
      • Tonsils , in pharynx; Peyer patches located in intestine; and appendix
  • 6. Figure 30.2 The lymphatic organs
  • 7. The Bodys First Line of Defense Against Disease Is Nonspecific and Innate
  • 8. 30.3 Barriers to entry, complement proteins, and certain blood cells are first responders
    • Barriers to entry such as the skin
      • Nonchemical, mechanical barriers, such as the skin and the mucous membranes
      • Protective proteins
        • Complement proteins are composed of a number of blood plasma proteins that complement certain immune responses and help destroy pathogens in three ways
          • Bind to mast cells and trigger histamine release to create enhanced inflammation
          • Bind to the surface of pathogens already coated with antibodies
          • Form a membrane attack complex that produces holes in the surface of some bacteria and viruses
        • Interferons are cytokines - soluble proteins that affect the behavior of other cells
    • Inflammatory response
  • 9. Phagocytes and Natural Killer Cells
    • Neutrophils are cells that are able to leave the bloodstream and engulf bacteria in connective tissues
    • Eosinophils are phagocytic, but they are better known for mounting an attack against animal parasites
      • The two most powerful of the phagocytic white blood cells are macrophages and macrophage - derived dendritic cells
    • Natural killer (NK) cells are large, granular lymphocytes that kill virus-infected cells and cancer cells by cell-to-cell contact
  • 10. Figure 30.3AOverview of nonspecific defenses
  • 11. Figure 30.3B Action of the complement system against a bacterium
    • Several hypotheses have been proposed as to the benefits of a fever
      • Perhaps a fever is the bodys way of informing us that something is wrong
      • At times, a fever may directly participate in overcoming an illness
        • Example: a fever can contribute to the hosts defense by providing an unfavorable environment for the invader
      • A fever may stimulate immunity
        • A fever has been shown to limit the growth of tumor cells more severely than that of normal body cells
  • 13. 30.5 The inflammatory response is a localized response to invasion
    • Inflammatory response - a series of events that occur whenever tissue is damaged
      • An inflamed area has four outward signs:
        • redness, heat, swelling, and pain
    • Steps in the inflammatory response
      • Chemical mediators, such as histamine , cause the capillaries to dilate and become more permeable
      • Migration of phagocytes, namely neutrophils and monocytes, also occurs during the inflammatory response
      • Macrophages also release colony-stimulating factors, cytokines that pass by way of the blood to the red bone marrow, where they stimulate the production and release of white blood cells
      • A blood clot can form to seal a break in a blood vessel
  • 14. Figure 30.5AInflammatory response
  • 15. Figure 30.5B A macrophage engulfing bacteria
  • 16. The Bodys Second Line of Defense Against Disease Is Specific to the Pathogen
  • 17. 30.6 The second line of defense targets specific antigens
    • Immunity is complete when a foreign substance is unable to cause an infection
      • First - specific defense requires that the body be able to recognize a particular molecule, an antigen
        • Other antigens are termed self-antigens because the body itself produces them
      • Second - after recognizing antigens, the immune system can respond to them
      • Third - the immune system can remember antigens it has met before
  • 18. 30.7 Specific immunity can be active or passive
    • Active Immunity
      • Develops naturally after a person is infected with a pathogen
      • Vaccine contains antigens that cause body to develop antibodies specific to these antigens
    • Passive Immunity
      • Occurs when an individual is given prepared antibodies (immunoglobulins) to combat a disease
        • Since these antibodies are not produced by the individuals plasma cells, passive immunity is short-lived
        • Even though passive immunity does not last, it is sometimes used to prevent illness in a patient who has been unexpectedly exposed to an infectious disease
  • 19. Figure 30.7A Vaccines immunize children against diseases Figure 30.7B Breastfeeding provides infants with antibodies
  • 20. 30.8 Lymphocytes are directly responsible for specific defenses
    • Specific defenses primarily depend on two types of lymphocytes - B cells and T cells
      • Capable of recognizing antigens because they have specific antigen receptors
        • B