Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Memmler’s The Human Body in Health and Disease 11 th edition Chapter 16 The Lymphatic System and Lymphoid Tissue To know better is to do better. Oprah Winfrey

Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Functions of the Lymphatic System Fluid balance –Lymph fluid Protection from infection Absorption of fats

Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins The lymphatic system in relation to the cardiovascular system. Lymphatic vessels pick up fluid in the tissues and return it to the blood in vessels near the heart. What type of blood vessel receives lymph collected from the body?

Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Lymphatic Capillaries Capillary walls (endothelium) are flattened epithelial cells More permeable than blood capillaries Overlapping cells form one-way valves Arise blindly (closed at one end) Lacteals absorb digested fats called CHYLE

Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Lymphatic Vessels Superficial sets Deep sets Nodes Right lymphatic duct Thoracic duct (left lymphatic duct) –Cisterna chyli

Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Vessels and nodes of the lymphatic system. (A) Lymph nodes and vessels of the head. (B) Drainage of right lymphatic duct and thoracic duct into subclavian veins.

Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Lymphoid Tissue Distributed throughout the body Makes up specialized organs of lymphatic system Grouping –Cervical nodes –Axillary nodes –Mesenteric nodes –Inguinal nodes

Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Structure of a lymph node. (A) Arrows indicate the flow of lymph through the node. (B) Section of a lymph node as seen under the microscope (low power). (B, Reprinted with permission from Cormack DH. Essential Histology. 2nd ed. Philadelphia: Lippincott Williams & Wilkins, 2001.) What type of lymphatic vessel carries lymph into a node? What type of lymphatic vessel carries lymph out of a node?

Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins The Spleen Cleanses blood –Filtration –Phagocytosis Destroys old red blood cells Produces red blood cells before birth Is a reservoir for blood

Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins The Thymus Plays key role in early immune system development Produces thymosin –Develops T lymphocyte cells –Promotes lymphocyte growth –Promotes lymphoid tissue activity Shrinks after puberty

Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins The Tonsils Remove contaminants and trap pathogens –Palatine tonsils –Pharyngeal tonsil (adenoids) –Lingual tonsils Surgery to treat if recurrent infection or enlarged tonsils make swallowing/breathing difficult Other Lymphoid Tissue - Appendix –Mucosal-associated lymphoid tissue (MALT) Peyer patches –Gut-associated lymphoid tissue (GALT)

Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins The Reticuloendothelial System Cells responsible for destroying worn-out blood cells, bacteria, cancer cells and other harmful foreign substances Monocytes Macrophages –Kupffer cells (Liver) –Dust cells (pulmonary macrophages)

Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Disorders of the Lymphatic System and Lymphoid Tissue Lymphangitis Septicemia Lymphadenitis –Cervical –Chronic

Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Lymphedema Tissue swelling due to obstruction of lymph flow caused by Infection of lymphatic vessels Vessel blockage –Malignant growth –Parasites Loss of lymphatic vessels from injury or surgery

Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Lymphadenopathy Enlarged lymph nodes accompany certain diseases and infections Acquired immunodeficiency syndrome (AIDS) Infectious mononucleosis Mumps

Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Splenomegaly Enlarged spleen accompanies certain diseases and infections Scarlet fever Typhus fever Typhoid fever Syphilis Tropical parasitic diseases Splenic anemia

Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Lymphoma Any tumor in lymphoid tissue Malignant disease –Hodgkin disease (has Reid- Sternberg cells) –Non-Hodgkin lymphoma (does not have R-S cells)

Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Body Defenses, Immunity, and Vaccines The Immune System Types of general body defenses against disease Nonspecific defenses –Effective against any harmful agent Specific defenses –Effective against a certain agent only

Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Why Do Infections Occur? Factors involved in infection Portal of entry Virulence of organism –Aggressiveness –Toxin production Dose (number) of pathogens Individual condition (predisposition) to infection

Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Nonspecific Defenses Successive lines of defense Simple outer barriers More complicated responses Immunity (ultimate defense mechanism)

Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Chemical and Mechanical Barriers Skin Mucous membranes –Cilia Body secretions –Tears –Perspiration –Saliva –Digestive juices Reflexes –Sneezing –Coughing –Vomiting –Diarrhea

Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Phagocytosis White blood cells take in and destroy waste and foreign material Neutrophils Macrophages

Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Natural Killer Cells Type of lymphocyte Can recognize body cells with abnormal membranes Found in lymph nodes, spleen, bone marrow, blood Secrete protein that breaks down cell membrane

Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Inflammation Infection is inflammation caused by pathogens Inflammatory reaction –Heat, redness, swelling, pain * –Cells release histamine –Leukocytes enter tissue Granulocytes, macrophages, mast cells –Leukocytes and plasma produce inflammatory exudate –Pus is produced –Lymph nodes enlarge

Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Fever As phagocytes work, they release substances that raise body temperature Stimulates phagocytes Increases metabolism Decreases some organisms’ ability to multiply

Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Interferon Group of substances that prevent nearby cells from producing more virus –IFN a (alpha) –IFN b (beta) –IFN g (gamma) Also acts nonspecifically on immune system cells

Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins ImmunityImmunity Power to overcome a specific disease agent Innate immunity –Inherited in genes Adaptive immunity –Most develops after birth, during life time, in response to encounters with specific harmful agents –Acquired naturally or artificially –Active or passive

Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Antigens Foreign substances that enter body Induce immune response of certain lymphocytes –T cells –B cells

Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins T Cells Originate in stem cells in bone marrow Change to T cells in thymus Become sensitized to specific antigens Produce cell-mediated immunity –Cytoxic T cells –Helper T cells –Regulatory T cells –Memory T cells Macrophages

Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Activation of a helper T cell by a macrophage (antigen- presenting cell). What is contained in the lysosome that joins the phagocytic vesicle?

Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins B Cells and Antibodies Antibody (Ab) also known as immunoglobulin (Ig) is substance produced in response to antigen Manufactured by B cells (B lymphocytes) Must mature in fetal liver or in lymphoid tissue Provides humoral immunity Contained in gamma globulin fraction of blood plasma

Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Activation of B cells. The B cell combines with a specific antigen. The cell divides to form plasma cells, which produce antibodies. Some of the cells develop into memory cells, which protect against reinfection. What two types of cells develop from activated B cells?

Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins 4 Types of Immunity Artificial Immunity Active – give a weak antigen in a vaccine form to make your body WORK to build a defense system Passive – already exposed to antigen; Nurse GIVES a pre- made immunoglobulin for instant protection Natural Immunity Active – get a virus and the body has to WORK to form antibodies to virus Passive – mother GIVES immunity to the fetus before birth You keep what you work to gain. LM 2011

Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins The Antigen–Antibody Reaction Complement is the enzymatic activity of a group of nonspecific proteins in blood that: Coats foreign cells Destroys cells Promotes inflammation Attracts phagocytes

Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Types of Vaccines Live Attenuated Toxoid Killed by heat or chemicals Antigenic component Genetically engineered

Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Boosters Active immunity does not always last a lifetime Repeated inoculations (booster shots) help maintain high titer of antibodies in the blood Number and timing varies with vaccines

Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Disorders of the Immune System Resulting from overactivity –Allergy –Autoimmune disease Resulting from underactivity –Hereditary –Infections –Environmental

Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins AutoImmune Abnormal reactivity to one’s own tissues Factors –Disease –Loss of immune system control –Cross-reaction of antibodies and self antigens Treatments –Immune-suppressing drugs –Chemotherapy/stem cell replacement

Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Immune Deficiency Diseases Failure of immune system May involve any part of system Varies in severity Congenital or acquired (e.g., AIDS) HIV –A retrovirus; uses reverse transcriptase enzyme

Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Multiple Myeloma Cancer of blood-forming bone marrow cells Effects of disease –Lowered resistance to infection –Anemia –Bone pain –Bone tissue loss –Kidney failure Treatment –Chemotherapy –Bone marrow transplants

Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Transplantation and Rejection Syndrome Caused by normal antigen–antibody reaction Reduced by –Tissue typing –Immune suppression drugs

Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Questions?