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Chapter 15: The Lymphatic System and Immunity Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins Taylor: Memmler’s Structure and Function of the Human Body The Lymphatic System • System of tissues and vessels • Scattered throughout the body • Services almost all regions Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins Taylor: Memmler’s Structure and Function of the Human Body Functions of the Lymphatic System • Fluid balance – Lymph fluid • Protection from infection – lymphocytes • Absorption of fats Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins Taylor: Memmler’s Structure and Function of the Human Body 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. Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins Taylor: Memmler’s Structure and Function of the Human Body Pathway of lymphatic drainage in the tissues. Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins Taylor: Memmler’s Structure and Function of the Human Body Lymphatic Circulation • One-way system • Begins in tissues • Ends in bloodstream Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins Taylor: Memmler’s Structure and Function of the Human Body 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 – Fats are transported into lymphatic vessels until lymph is added to the blood Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins Taylor: Memmler’s Structure and Function of the Human Body Lymphatic Vessels • Thin walled, delicate • Have a beaded appearance • Superficial sets • Deep sets • Nodes Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins Taylor: Memmler’s Structure and Function of the Human Body Right Lymphatic Duct • Short vessel • Receives lymph that comes from superior right quadrant – Right side of head, neck, thorax • Empties into right subclavian vein Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins Taylor: Memmler’s Structure and Function of the Human Body Thoracic Duct • Left lymphatic duct • Larger of two vessels • Receives lymph from all parts of the body except those above the diaphragm on right side • Cisterna chyli – First portion – Storage pouch Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins Taylor: Memmler’s Structure and Function of the Human Body 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 © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins Taylor: Memmler’s Structure and Function of the Human Body Movement of Lymph • Segments of vessels located between the valves contract rhythmically • Skeletal muscles compress vessels Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins Taylor: Memmler’s Structure and Function of the Human Body Lymphoid Tissue • Distributed throughout the body • Makes up specialized organs of lymphatic system Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins Taylor: Memmler’s Structure and Function of the Human Body Lymph Nodes • Grouping • Structure – – Fibrous connective tissue capsule from which partitions (trabeculae) extend into nodes substance Afferent lymphatic vessel • Hilum – Sinuses – Cords – Nodules – Medulla – Efferent lymphatic vessel – Cervical nodes – Axillary nodes – Mesenteric nodes – Inguinal nodes Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins Taylor: Memmler’s Structure and Function of the Human Body The Spleen • Cleanses blood – Filtration – Phagocytosis • Destroys old red blood cells • Produces red blood cells before birth • Is reservoir for blood Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins Taylor: Memmler’s Structure and Function of the Human Body Location of lymph tissue. Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins Taylor: Memmler’s Structure and Function of the Human Body 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 © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins Taylor: Memmler’s Structure and Function of the Human Body The Tonsils Remove contaminants and trap pathogens • Palatine tonsils • Pharyngeal tonsil (adenoids) • Lingual tonsils Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins Taylor: Memmler’s Structure and Function of the Human Body Location of the tonsils. Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins Taylor: Memmler’s Structure and Function of the Human Body Other Lymphoid Tissue • Appendix • Mucosal-associated lymphoid tissue (MALT)-prevents microorganisms from invading deeper tissues – Peyer patches • Gut-associated lymphoid tissue (GALT) – Includes peyer patches, tonsils and appendix Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins Taylor: Memmler’s Structure and Function of the Human Body The Reticuloendothelial System Cells responsible for destroying worn-out blood cells, bacteria, cancer cells and other harmful foreign substances •Monocytes – Develop into macrophages •Macrophages – Kupffer cells • Located in the liver sinusoids – Dust cells • Ingest solid particles that enter the lungs Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins Taylor: Memmler’s Structure and Function of the Human Body Body Defenses Against Disease • Types of general body defenses against disease • Nonspecific defenses – Effective against any harmful agent • Specific defenses – Effective against a certain agent only Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins Taylor: Memmler’s Structure and Function of the Human Body Nonspecific Defenses Successive lines of defense • Simple outer barriers • More complicated responses • Immunity (ultimate defense mechanism) Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins Taylor: Memmler’s Structure and Function of the Human Body Chemical and Mechanical Barriers • Skin • Mucous membranes – **Cilia • Body secretions – Tears – Perspiration – Saliva – Digestive juices • Reflexes – Sneezing – Coughing – Vomiting – Diarrhea Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins Taylor: Memmler’s Structure and Function of the Human Body Phagocytosis White blood cells take in and destroy waste and foreign material • Neutrophils • Macrophages Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins Taylor: Memmler’s Structure and Function of the Human Body 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 © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins Taylor: Memmler’s Structure and Function of the Human Body 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 © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins Taylor: Memmler’s Structure and Function of the Human Body Fever As phagocytes work, they release substances that raise body temperature • Stimulates phagocytes • Increases metabolism • Decreases some organisms’ ability to multiply Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins Taylor: Memmler’s Structure and Function of the Human Body 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 © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins Taylor: Memmler’s Structure and Function of the Human Body Specific Defenses—Immunity • Power to overcome a specific disease agent • Innate immunity – Inherited in genes • Adaptive immunity – Develops after birth – Acquired naturally or artificially – Active or passive Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins Taylor: Memmler’s Structure and Function of the Human Body Types of immunity Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins Taylor: Memmler’s Structure and Function of the Human Body Innate Immunity Differences in physical constitution • Species immunity • Individual immunity Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins Taylor: Memmler’s Structure and Function of the Human Body Adaptive Immunity Develops in a person • During lifetime • From encounters with specific harmful agents Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins Taylor: Memmler’s Structure and Function of the Human Body Antigens • Foreign substances that • Enter body • Induce immune response of certain lymphocytes – T cells – B cells Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins Taylor: Memmler’s Structure and Function of the Human Body 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 • Prevents overactivity – Memory T cells • Macrophages – Phagocytic – Insert fragments of the foreign antigen into their plasma membrane, antigen then displayued on the macrophages surface in combination with antigens that a T cell can recognize as belonging to the self Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins Taylor: Memmler’s Structure and Function of the Human Body 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 © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins Taylor: Memmler’s Structure and Function of the Human Body 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. Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins Taylor: Memmler’s Structure and Function of the Human Body The Antigen–Antibody Reaction • Effects – Prevents attachment of pathogens – Causes clumping of antigen – Neutralizes toxins – Aids phagocytosis – Activates NK cells – Activates complement • Group of enzymes • Acts non-specifically Promotes phagocytosis Destroys cells Promotes inflammation Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins Taylor: Memmler’s Structure and Function of the Human Body Naturally Adaptive Immunity Immunity acquired through contact with a specific disease organism • Active immunity • Passive immunity Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins Taylor: Memmler’s Structure and Function of the Human Body Figure 15-7 Nonspecific immunity. Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins Taylor: Memmler’s Structure and Function of the Human Body Artificial Adaptive Immunity Vaccination (immunization) can cause a person’s immune system to manufacture antibodies • Preventive measure • Risk of side effects Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins Taylor: Memmler’s Structure and Function of the Human Body Types of Vaccines • Live • Attenuated • Toxoid • Killed by heat or chemicals • Antigenic component • Genetically engineered Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins Taylor: Memmler’s Structure and Function of the Human Body 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 © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins Taylor: Memmler’s Structure and Function of the Human Body Passive Immunity Acquired by administration of immune serum (antiserum) • Short-lived immunity • Used in emergencies • Often derived from animals • May cause sensitivity reaction Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins