The Lymphatic and Immune Systems 13 The Lymphatic and Immune Systems

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

(15 mins) Film Viewing https://www.youtube.com/watch?v=H2VkW9L5QSU   Buzz Session 1. 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.

Introduction Immune system Lymphatic 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

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

Lymphatic Pathways Lymphatic capillaries Lymphatic vessels 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

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

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

Back

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

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

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

The Thymus and Spleen (cont.) 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

Apply Your Knowledge Correct! 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!

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

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

Defenses Against Disease (cont.) Two major types of lymphocytes 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 attack them directly Secrete lymphokines that increase T cell production and directly kill cells with antigens

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

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

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

Apply Your Knowledge Right on Target! 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 B Right on Target!

Antibodies Also called immunoglobulins IgA IgD IgE 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

Antibodies (cont.) IgG IgM Recognizes bacteria, viruses, and toxins Activates complements IgM Large and binds to antigens on food, bacteria, or incompatible blood cells Activates compliments

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

Very Good! 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!

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

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

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)

Apply Your Knowledge Good Answer! 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!

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

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

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

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

Common Immune System Disorders (cont.) Description AIDS Development 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 Lymphedema Blockage of lymphatic vessels results in tissue swelling that increases over time

Common Immune System Disorders (cont.) Description 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

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

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