The Lymphatic and Immune Systems

1. 28 The Lymphatic and Immune Systems

2. Learning Outcomes 28.1 List the pathways and organs of the lymphatic system and give their locations. 28.2 Define lymph and tell how it is circulated in the body. 28.3 Define the terms infection, pathogen, and antigen. 28.4 List and describe the nonspecific body defense mechanisms. 28.5 Explain the signs and causes of inflammation.

3. Learning Outcomes (cont.) 28.6 Explain what is meant by body defenses. 28.7 Define B cells and T cells and describe their locations and functions. 28.8 Explain the importance of MHC proteins. 28.9 List the different types of T cells and describe their functions. 28.10 Explain how antibodies fight infection.

4. Learning Outcomes (cont.) 28.11 List the different types of antibodies and tell how they differ. 28.12 Define complement proteins and give their function. 28.13 Explain the difference between the primary immune response and secondary immune response. 28.14 Explain the four different types of acquired immunities. 28.15 Describe the function of a vaccine.

5. Learning Outcomes (cont.) 28.16 Define the terms cancer and carcinogen. 28.17 Describe how cancers are diagnosed and treated. 28.18 Explain how cancers are classified. 28.19 Describe how allergies develop. 28.20 Describe the causes, signs and symptoms, and treatments of other common immune disorders.

6. 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 Introduction

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

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

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

10. 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

11. Back

12. Lymph Nodes • Small, glandular structures • Located along paths of larger lymphatic vessels • Afferent lymphatic vessels – Lymph to node • Efferent lymphatic vessels – Lymph from node

13. 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

14. 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

15. 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

16. 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. Correct!

17. 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 Defenses Against Disease

18. 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 Specific Defenses Against Disease

19. Two major types of lymphocytes Defenses Against Disease (cont.) Diagram B Cells and T Cells Recognize antigens in the body • B cells • Respond to antigens by becoming plasma cells • Plasma cells make antibodies • Memory B cells produce stronger response with next exposure to antigen • T Cells • Cell-mediated response • Bind to antigens on cells and attackthem directly • Secrete lymphokines that increase T cell production and directly kill cells with antigens

20. 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

21. 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

22. Defenses Against Disease (cont.) • Natural killer (NK) cells • Type of lymphocyte • Primarily target cancer cells • Kill on contact • Do not recognize a specific antigen

23. 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 ANSWER: NK B T T NK T Right on Target! B

24. 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

25. 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

26. 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

27. 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!

28. 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

29. 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

30. 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

31. Apply Your Knowledge 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. 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. Good Answer!

32. 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

33. 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

34. 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

35. 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

36. Common Immune System Disorders (cont.)

37. Common Immune System Disorders (cont.)

38. Apply Your Knowledge Excellent! Matching: ___ Immune response to a substance A. CFS ___ Blockage of lymphatic vessels B. SLE ___ “Kissing disease” C. Cancer ___ “Butterfly” rash on face D. Autoimmune disease ___ Severe tiredness E. Lymphedema ___ Uncontrolled growth of abnormal cells F. Mononucleosis ___ Body attacks its own antigens G. Allergy ANSWER: G E F B A C D

39. In Summary 28.1 The 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. 28.2 Lymph 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.

40. 28.3 Infection 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.  28.4 The nonspecific body defenses include species resistance, mechanical and chemical barriers, phagocytosis, fever, and inflammation. 28.5 Inflammation is the result of injury or infection. Signs are redness, heat, swelling, and pain. In Summary (cont.)

41. In Summary (cont.) 28.6 Specific defenses are immunities or defenses against very specific antigens. 28.7 B 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.

42. 28.8 T cells cannot be activated to produce immunity without MHC proteins and macrophages. 28.9 Activated 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. 28.10 Antibodies may work in the following ways: phagocytosis, antigen clumping, covering (inactivating) toxic portions of antigens, and activating complements. In Summary (cont.)

43. In Summary (cont.) 28.11 Antibodies 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.

44. In Summary (cont.) 28.12 Complements are serum proteins that attack pathogens by forming holes in them. They also attract macrophages and can stimulate inflammation. 28.13 A 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.

45. In Summary (cont.) 28.14 The 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.

46. In Summary (cont.) 28.15 Vaccines are used to produce artificially acquired active immunity. 28.16 Cancer is defined as the uncontrolled growth of abnormal cells. A carcinogen is an agent that is known to cause cancer. 28.17 Cancer 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.

47. In Summary (cont.) 28.18 Cancers are classified as Stages IIV and recurrent. Definitions of these stages may be found in Table 28-1. 28.19 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.

48. In Summary (cont.) 28.20 Diseases 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.

49. End of Chapter 28 Thought is an infection. In the case of certain thoughts, it becomes an epidemic. ~Wallace Stevens