Explore the Lymphatic System: Functions, Structures, and Immune Response

1. 13 The Lymphatic and Immune Systems

2. Learning Outcomes Animal Organ-System and Its Functions: The ENDOCRINE System - STEM_BIO11/12- IVa-h-1 • Give the functions of the LYMPHATIC organ-system • Identify the structures and functions of the LYMPHATIC organs • Evaluate the process of IMMUNITY, INFECTIONS, PATHOGEN & ANTIGEN • Describe the Pathophysiology of the LYMPHATIC System

3. (15 mins) Film Viewing https://www.youtube.com/watch?v=H2VkW9L5QSU Buzz Session1. What is the importance of the Lymphatic System? 2. What is it made of? Structures and parts/functions?3. What are Immunity, Antibody and Antigen in the Body and how does it work 4. What are disorders of the Lymphatic system System? Describe.

4. 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

5. 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

6. 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

7. 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

8. 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

9. Back

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

11. 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

12. 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

13. 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

14. 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!

15. 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

16. 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

17. 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

18. 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

19. 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

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

21. 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

22. 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

23. 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

24. 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

25. 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!

26. 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

27. 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

28. 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

29. 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!

30. 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

31. 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

32. 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

33. 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

34. Common Immune System Disorders (cont.)

35. Common Immune System Disorders (cont.)

36. 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

37. End of Chapter 13 Thought is an infection. In the case of certain thoughts, it becomes an epidemic. ~Wallace Stevens