CHAPTER © 2011 The McGraw-Hill Companies, Inc. All rights reserved. 4 The Lymphatic and Immune Systems

© 2011 The McGraw-Hill Companies, Inc. All rights reserved. 4-2 Learning Outcomes 4.1List the pathways and organs of the lymphatic system and give their locations. 4.2Define lymph and tell how it is circulated in the body. 4.3Define the terms infection, pathogen, and antigen. 4.4List and describe the nonspecific body defense mechanisms. 4.5Explain the signs and causes of inflammation.

© 2011 The McGraw-Hill Companies, Inc. All rights reserved. 4-3 Learning Outcomes (cont.) 4.6Explain what is meant by body defenses. 4.7Define B cells and T cells and describe their locations and functions. 4.8 Explain the importance of MHC proteins. 4.9 List the different types of T cells and describe their functions. 4.10Explain how antibodies fight infection.

© 2011 The McGraw-Hill Companies, Inc. All rights reserved. 4-4 Learning Outcomes (cont.) 4.11List the different types of antibodies and tell how they differ. 4.12Define complement proteins and give their function. 4.13Explain the difference between the primary immune response and secondary immune response. 4.14Explain the four different types of acquired immunities. 4.15Describe the function of a vaccine.

© 2011 The McGraw-Hill Companies, Inc. All rights reserved. 4-5 Learning Outcomes (cont.) 4.16Define the terms cancer and carcinogen. 4.17Describe how cancers are diagnosed and treated. 4.18Explain how cancers are classified. 4.19Describe how allergies develop. 4.20Describe the causes, signs and symptoms, and treatments of other common immune disorders.

© 2011 The McGraw-Hill Companies, Inc. All rights reserved. 4-6 Introduction Immune system –Protects the body against Bacteria Viruses Fungi Toxins Parasites Cancer Lymphatic system –Works with immune system to remove disease-causing agents –Organs Thymus Spleen Lymph nodes

© 2011 The McGraw-Hill Companies, Inc. All rights reserved. 4-7 The Lymphatic System Network of connecting vessels –Collects fluid (lymph) between cells and returns it to bloodstream –Picks up lipids from digestive organs and transports them to bloodstream –Functions to defend the body against pathogens

© 2011 The McGraw-Hill Companies, Inc. All rights reserved. 4-8 Lymphatic Pathways Lymphatic capillaries –Extend into interstitial spaces –Permeable, thin walls pick up fluid, now lymph –Delivers lymph to lymphatic vessels Lymphatic vessels –Deliver lymph to lymph nodes Cells in nodes can remove pathogens from lymph and start an immune response –Leaves nodes through efferent lymphatic vessels Lymph System

© 2011 The McGraw-Hill Companies, Inc. All rights reserved. 4-9 Lymphatic Pathways (cont.) Lymphatic trunks –Receive lymph from efferent lymphatic vessels –Deliver it to Lymphatic collecting ducts –Thoracic duct Left side of head and neck, left arm, left side of thorax, entire abdominopelvic area, and both legs –Right lymphatic duct Right side of head and neck, right arm, and right side of chest Lymph System

© 2011 The McGraw-Hill Companies, Inc. All rights reserved Tissue Fluid and Lymph Interstitial fluid –Fluid in spaces between cells that has leaked from blood capillaries and has not been picked up by body cells –High in nutrients, oxygen, and small proteins –Becomes lymph Pushed through lymphatic vessels by squeezing action of neighboring skeletal muscles and breathing movement

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© 2011 The McGraw-Hill Companies, Inc. All rights reserved Lymph Nodes Small, glandular structures Located along paths of larger lymphatic vessels –Afferent lymphatic vessels – Lymph to node –Efferent lymphatic vessels – Lymph from node

© 2011 The McGraw-Hill Companies, Inc. All rights reserved Lymph Nodes (cont.) More lymph enters than can leave at one time Cells in nodes –Macrophages – digest unwanted pathogens –Lymphocytes – start an immune response against pathogen Nodes can generate some lymphocytes

© 2011 The McGraw-Hill Companies, Inc. All rights reserved The Thymus and Spleen Thymus –Soft, bi-lobed organ –Located just above the heart in the mediastinum –Large in children, shrinks as we age –Functions Same as lymph nodes Also produces lymphocytes Produces thymosin – stimulates production of lymphocytes

© 2011 The McGraw-Hill Companies, Inc. All rights reserved The Thymus and Spleen (cont.) Spleen –Largest lymphatic organ –Located in the upper left quadrant of abdominal cavity –Functions Filters blood similarly to lymph nodes Removes worn-out red cells –If removed (splenectomy), liver takes over most of its function

© 2011 The McGraw-Hill Companies, Inc. All rights reserved Apply Your Knowledge What are the lymphatic collecting ducts and what area do they drain? ANSWER: The collecting ducts are: Thoracic duct, which drains the left side of the head and neck, left arm, left side of thorax, entire abdominopelvic area, and both legs; and the right lymphatic duct, which drains the right side of the head and neck, right arm, and right side of the chest.

© 2011 The McGraw-Hill Companies, Inc. All rights reserved Defenses Against Disease Infection –The presence of a pathogen in or on the body Pathogen –A disease-causing agent Innate immunity –Nonspecific defenses to protect against pathogens Nonspecific defenses –Species resistance –Mechanical barriers –Chemical barriers –Phagocytosis –Fever –Inflammation

© 2011 The McGraw-Hill Companies, Inc. All rights reserved Specific Defenses Against Disease Immunities –Protect against very specific pathogens –Antigens Foreign substances in the body –Haptens Foreign substances too small to start an immune response by themselves Other substances –Proteins – antibodies and complements –WBCs – lymphocytes and macrophages –Lymph system Cytokines – assist in immune response regulation Monokines – increase B cell production and stimulate WBC production

© 2011 The McGraw-Hill Companies, Inc. All rights reserved Defenses Against Disease (cont.) Two major types of lymphocytes B Cells and T Cells Recognize antigens in the body T Cells  Cell-mediated response  Bind to antigens on cells and attack them directly  Secrete lymphokines that increase T cell production and directly kill cells with antigens T Cells  Cell-mediated response  Bind to antigens on cells and attack them directly  Secrete lymphokines that increase T cell production and directly kill cells with antigens B cells  Respond to antigens by becoming plasma cells  Plasma cells make antibodies  Memory B cells produce stronger response with next exposure to antigen B cells  Respond to antigens by becoming plasma cells  Plasma cells make antibodies  Memory B cells produce stronger response with next exposure to antigen Diagram

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© 2011 The McGraw-Hill Companies, Inc. All rights reserved Defenses Against Disease (cont.) T cell activation –Begins when macrophage ingests and digests pathogen with antigen on it –Antigens are placed on cell membrane of macrophage –T cell recognizes and binds to antigen and the major histocompatibility complex (MHC) on the surface of the macrophage –Now can divide to form other types of T cells

© 2011 The McGraw-Hill Companies, Inc. All rights reserved Defenses Against Disease (cont.) Types –Cytotoxic T cells Protect body against viruses and cancer cells –Helper T cells Increase antibody formation, memory cell formation, B cell formation, and phagocytosis –Memory T cells Remember the pathogen that activated original T cell Later exposures trigger an immune response more effective than initial response

© 2011 The McGraw-Hill Companies, Inc. All rights reserved Defenses Against Disease (cont.) Natural killer (NK) cells –Type of lymphocyte –Primarily target cancer cells –Kill on contact –Do not recognize a specific antigen

© 2011 The McGraw-Hill Companies, Inc. All rights reserved Apply Your Knowledge Identify whether each item refers to T cells, B cells, or NK cells: ___ Primarily target cancer cells ___ Respond to antigens by becoming plasma cells ___ Must be activated to respond to an antigen ___ Bind to antigens on cells and attack them directly ___ Kill on contact ___ Need macrophages and MHC for activation ___ Make antibodies against specific antigen B NK T T T B ANSWER: Right on Target!

© 2011 The McGraw-Hill Companies, Inc. All rights reserved Antibodies Also called immunoglobulins – IgA Prevents pathogens from entering body –IgD Found on B cell membranes Thought to control B cell activity –IgE Found with IgA Involved in triggering allergic reactions

© 2011 The McGraw-Hill Companies, Inc. All rights reserved Antibodies (cont.) –IgG Recognizes bacteria, viruses, and toxins Activates complements –IgM Large and binds to antigens on food, bacteria, or incompatible blood cells Activates compliments

© 2011 The McGraw-Hill Companies, Inc. All rights reserved Antibodies (cont.) Actions that occur when antibodies bind to antigens –Allow phagocytes to recognize and destroy antigens –Cause antigens to clump together, causing them to be destroyed by macrophages –Cover the toxic portions of antigens, making them harmless –Activate complement Group of proteins in serum that attack pathogens by forming holes in them Attract macrophages to pathogens and can stimulate inflammation

© 2011 The McGraw-Hill Companies, Inc. All rights reserved Apply Your Knowledge What are the possible actions that occur when antibodies bind to antigens? ANSWER: Possible actions include:  They allow phagocytes to recognize and destroy antigens.  They make antigens clump together, causing them to be destroyed by macrophages.  They cover the toxic portions of antigens to make them harmless.  They activate complements. Very Good!

© 2011 The McGraw-Hill Companies, Inc. All rights reserved Immune Responses and Acquired Immunity Primary immune response occurs with first exposure to antigen –Slow process –Memory cells are formed Secondary immune response with next exposure to same antigen –Quick and carried out by memory cells –Usually prevents person from developing disease from the antigen

© 2011 The McGraw-Hill Companies, Inc. All rights reserved Immune Responses and Acquired Immunity (cont.) Naturally acquired active immunity –Natural exposure to antigen – having an illness –Makes antibodies and memory cells –Long-lasting Artificially acquired active immunity –Injected with pathogen – immunizations or vaccines –Makes antibodies and memory cells –Long-lasting

© 2011 The McGraw-Hill Companies, Inc. All rights reserved Immune Responses and Acquired Immunity (cont.) Naturally acquired passive immunity –Acquired from mother Breast milk Placenta –Short-lived Artificially acquired passive immunity –Injected with antibodies (such as antivenom) –Short-lived

© 2011 The McGraw-Hill Companies, Inc. All rights reserved Apply Your Knowledge ANSWER: Immunization is an artificially acquired immunity because a person develops this immunity by being injected with a pathogen and then making antibodies and memory cells against the pathogen. After you give an immunization to a 2-year-old, her mother asks you why this will work to prevent her from getting a disease.

© 2011 The McGraw-Hill Companies, Inc. All rights reserved Major Immune System Disorders Cancer –Uncontrolled growth of abnormal cells form malignant tumors –Factors known to cause cancer are called carcinogens –Treatment based on stage 0 – very early; cancer cells localized I – spread to deeper layers or some in surrounding tissues II – spread to surrounding tissues but contained in primary site III – spread beyond primary site into nearby areas IV – spread to other organs Recurrent – reappeared after treatment

© 2011 The McGraw-Hill Companies, Inc. All rights reserved Major Immune System Disorders (cont.) Allergies –Immune response to an allergen –IgE antibodies bind to allergens and stimulate mast cells to release histamine and heparin, triggering allergic response –Allergy shots Small amounts of allergen stimulates production of IgG to prevent IgE from binding to antigen IgG antibodies do not stimulate mast cells, so immune response is not generated

© 2011 The McGraw-Hill Companies, Inc. All rights reserved Major Immune System Disorders (cont.) –Allergy signs/symptoms Inhaled allergens – runny nose, sneezing, coughing, wheezing Ingested allergens – nausea, vomiting, diarrhea Skin allergens – rashes Allergens in blood – most life-threatening; can affect many organs –Treatment Antihistamines, decongestants – OTC or prescription Epinephrine for anaphylaxis – vasoconstriction, increasing BP –Anaphylaxis – life-threatening response

© 2011 The McGraw-Hill Companies, Inc. All rights reserved Common Immune System Disorders Autoimmune disease –Body attacks its own antigens –Examples Scleroderma Rheumatoid arthritis Multiple sclerosis Glomerulonephritis Crohn’s disease Diabetes mellitus, type I

© 2011 The McGraw-Hill Companies, Inc. All rights reserved Common Immune System Disorders (cont.) DisorderDescription AIDSDevelopment of severe signs and symptoms caused by HIV as it destroys lymphocytes; leaves immune system weakened and susceptible to other diseases Chronic fatigue syndrome (CFS) Condition of severe tiredness not relieved by rest and not related to other illnesses LymphedemaBlockage of lymphatic vessels results in tissue swelling that increases over time

© 2011 The McGraw-Hill Companies, Inc. All rights reserved Common Immune System Disorders (cont.) DisorderDescription Mononucleosis“Mono”; highly contagious viral infection spread through saliva of infected person Systemic lupus erythematous (SLE) Autoimmune disorder; produces antibodies that target own cells and tissues; affects women more often than men

© 2011 The McGraw-Hill Companies, Inc. All rights reserved Apply Your Knowledge Matching: ___ Immune response to a substanceA.CFS ___ Blockage of lymphatic vesselsB.SLE ___ “Kissing disease”C.Cancer ___ “Butterfly” rash on faceD.Autoimmune disease ___ Severe tirednessE.Lymphedema ___ Uncontrolled growth of abnormal cellsF.Mononucleosis ___ Body attacks its own antigensG.Allergy G F E D C B A ANSWER:

© 2011 The McGraw-Hill Companies, Inc. All rights reserved In Summary 4.1The lymph system is composed of pathways known as lymph vessels. In addition to the lymph vessels, the organs of the lymphatic system include lymph nodes located throughout the body, the thymus in the mediastinum, and the spleen located in the LUQ. 4.2Lymph is the body fluid found between the body’s cells. It circulates through the body via lymphatic capillaries, lymphatic vessels, lymph nodes, lymphatic trunk, collecting ducts, and to the subclavian vein.

© 2011 The McGraw-Hill Companies, Inc. All rights reserved In Summary (cont.) 4.3Infection is the presence of a pathogen in or on the body. A pathogen is a disease-causing agent, and antigens are foreign substances within the body that may or may not cause disease. 4.4The nonspecific body defenses include species resistance, mechanical and chemical barriers, phagocytosis, fever, and inflammation. 4.5Inflammation is the result of injury or infection. Signs are redness, heat, swelling, and pain.

© 2011 The McGraw-Hill Companies, Inc. All rights reserved In Summary (cont.) 4.6Specific defenses are immunities or defenses against very specific antigens. 4.7B and T cells come from the bone marrow, thymus, lymph nodes, spleen, and the lining of the digestive tract and are found circulating in the blood. B cells utilize memory and plasma cells in a process called humoral or antibody-mediated immunity, and T cells bind directly to cell antigens, attacking them directly, producing cell-mediated immunity.

© 2011 The McGraw-Hill Companies, Inc. All rights reserved In Summary (cont.) 4.8 T cells cannot be activated to produce immunity without MHC proteins and macrophages. 4.9Activated T cells may form cytotoxic cells which protect the body against viruses and certain types of cancer. Other T cells may become helper T cells, which increase antibody and memory cell and B cell formation and phagocytosis. Still other T cells become memory cells. 4.10Antibodies may work in the following ways: phagocytosis, antigen clumping, covering (inactivating) toxic portions of antigens, and activating complements.

© 2011 The McGraw-Hill Companies, Inc. All rights reserved In Summary (cont.) 4.11Antibodies are also known as immunoglobulins. IgA prevents pathogens from entering the body; IgD controls B cell activity; IgE works with IgA in triggering allergic reactions; IgG recognizes bacteria, viruses and toxins and activates complements; and IgM binds to antigens on food, bacteria, or incompatible blood cells. IgM also activates complements.

© 2011 The McGraw-Hill Companies, Inc. All rights reserved In Summary (cont.) 4.12Complements are serum proteins that attack pathogens by forming holes in them. They also attract macrophages and can stimulate inflammation. 4.13A primary immune response occurs the first time a person is exposed to an antigen. The response is slow and takes several weeks to occur. A secondary immune response occurs at the next exposure. This response is very quick and may prevent the person from becoming ill.

© 2011 The McGraw-Hill Companies, Inc. All rights reserved In Summary (cont.) 4.14The four types of immune response are natural active immunity, such as when someone becomes ill and develops immunity; artificial active immunity, as when an injection is given against a pathogen, preventing illness; natural passive immunity occurs when an infant has its mother’s immunity for a short while after birth and through breast-milk; and artificial passive immunity occurs after injection of antibodies such as with an antivenom.

© 2011 The McGraw-Hill Companies, Inc. All rights reserved In Summary (cont.) 4.15Vaccines are used to produce artificially acquired active immunity. 4.16Cancer is defined as the uncontrolled growth of abnormal cells. A carcinogen is an agent that is known to cause cancer. 4.17Cancer diagnoses can come about in many ways, but often a biopsy confirms the diagnosis. Treatments vary depending on the type and stage of the cancer, but treatment options include surgery, including bone marrow transplants, chemotherapy, and radiation therapy, as well as newer immune therapies.

© 2011 The McGraw-Hill Companies, Inc. All rights reserved In Summary (cont.) 4.18Cancers are classified as Stages I  IV and recurrent. Definitions of these stages may be found in Table An allergic reaction is an immune response to a substance that is not normally considered harmful to the body. Allergic reactions can also be an excessive immune response. Allergens are substances that produce an allergic response.

© 2011 The McGraw-Hill Companies, Inc. All rights reserved In Summary (cont.) 4.20Diseases and disorders of the immune system include autoimmune diseases, where the body attacks its own antigens, as well as numerous other diseases, including some cancers, caused by pathogens, allergens, and other antigens. The signs, symptoms and treatments are as numerous and varied as the diseases. Some of the more common diseases and disorders are discussed in the Pathophysiology section at the end of this chapter.

© 2011 The McGraw-Hill Companies, Inc. All rights reserved End of Chapter 4 Thought is an infection. In the case of certain thoughts, it becomes an epidemic. ~Wallace Stevens