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Lymphatic and Immune System Your Body’s Defense Mechanism 12 The Lymphatic and Immune Systems Lesson 12.1: The Lymphatic System Lesson 12.2: Nonspecific Defenses Lesson 12.3: Specific Defenses Lesson 12.4: Disorders and Diseases of the Immune System Chapter 12: The Lymphatic and Immune Systems Lesson 12.1 The Lymphatic System The Lymphatic System • organization of the lymphatic system – lymph formation and flow – lymph drainage • lymphatic cells, tissues, and organs – lymphatic cells – lymphatic tissues – lymphatic organs Lymphatic vs. Cardiovascular • Both systems extend throughout almost all parts of the body • Both have a network of vessels that vary in size from microscopic capillaries to large vessels • Unlike the cardiovascular system, the lymphatic system is not a closed loop Organization of the Lymphatic System Lymph Formation and Flow • fluid leaks out of blood vessel capillaries – about 4 liters per day (becomes interstitial fluid) • enters lymphatic capillaries • fluid is now called lymph • returns to circulatory system through lymphatic trunks Lymph Formation and Flow • No pump in the lymphatic system • Muscular contractions and movement of organs compress the vessels, moving lymph along its route • Contains lymphatic valves Lymph Drainage • Lymphatic trunks are named for their location and the part of the body they drain. – Left and right jugular trunks – Left and right subclavian trunks – Left and right bronchomediastinal trunk – Intestinal trunk – Left and right lumbar trunk Intestinal and lumbar trunks converge at the cisterna chyli, at diaphragm level in front of the vertebrae to forming an enlarged chamber Lymph Drainage • thoracic duct – drains legs, abdominopelvic area, left arm, and left side of the head and thorax • right lymphatic duct – drains right arm, right side of head, and right side of the thorax Lymph Drainage Lymphatic Cells • Lymphocytes – distinctive cells of the system (20%-30% of WBC) – T lymphocytes (T cells) mature in thymus – B lymphocytes (natural killer {NK} cells)mature in bone marrow • Macrophages – phagocytize foreign cells and substances, as well as activate T cells – begin as monocytes – leave lymphatic tissue to enter surrounding tissue Lymphatic Tissues • Loose connective tissue that contains many lymphocytes • mucosa-associated lymphatic tissue (MALT) – tonsils • Pharyngeal (adnoids) – back of the nasopharynx • Palatine – back of the mouth both left and right • Lingual – either side at the base of the tongue • lymphatic nodules – clusters formed by lymphocytes and macrophages Lymphatic Tissues • Peyer’s patches – clusters of MALT in the small intestines • MALT also protects the appendix Lymphatic Organs • lymph nodes – cleanse lymph trapping bacteria, viruses, and other harmful substances – store and produce T and B cells Lymphatic Organs • Spleen – Largest lymphatic organ in the body – Scans and cleans blood – Activates the Immune Response – Functional tissue • White pulp – rich in lymphocytes which monitor blood flowing for infectious cells and viruses • Red pulp – macrophages destroy old worn out red blood cells, platelets and pathogens • Because of the thin capsule and soft interior, the spleen may tear easily during a tramatic blow to the abdomen. Lymphatic Organs • Thymus – Lies behind the sternum and in front of heart, trachea and esophagus – nursery for T cells – Also and endocrine organ – Largest at childhood and steadily shrinks after puberty Review and Assessment Match these words with 1–4 below: right lymphatic duct, thoracic duct, tonsil, spleen. 1. drains left side of head 2. scan and clean blood 3. drains right side of head 4. palatine Chapter 12: The Lymphatic and Immune Systems Lesson 12.2 Nonspecific Defenses Physical Barriers • Skin – keratinized stratified squamous epithelium makes the skin a strong, flexible and impermeable barrier to infection • Hair – provide protection from chafing, sunburn, and insects • acidic secretions from sebaceous glands and sweat glands – contain toxic chemicals that hinder bacterial growth • mucous membranes – line the respiratory, digestive, urinary, and reproductive tracts Cellular and Chemical Defenses • Phagocytosis https://www.youtube.com/watch?v=rPLfnZHcICA – engulf foreign cells and debris – Neutrophils: most common WBC that moves out of the capillaries and into the surrounding tissues – macrophages (formerly monocytes):also leave the blood stream and enter tissues – Lysosomes: fuse with phagocytes to secrete digestive enzymes and acid to help destroy the target – Exocytosis Cellular and Chemical Defenses • natural killer cells: lymphocytes – Attracted to virus infected cells and cancer cells – release perforins (proteins that destroy foreign cells) to perforate cells – https://www.youtube.com/watch?v=HNP1E AYLhOs Cellular and Chemical Defenses • complement system – set of 11 proteins; complements, or balances out the effect of antibodies – classical pathway: recognizes antibodies bound to a target and activates the compliment-protein – alternative pathway: recognizes foreign materials • Opsonins – proteins that make cells more attractive to phagocytes • Opsonization – process of making cells more attractive The Complement System Cellular and Chemical Defenses • interferons – – – – – – released by virus infected cells Interfere with viral replication Help neighboring cells to resist infection Alpha: produced by virus infected leukocytes Beta: Produced by virus infected fibroblasts gamma interferons: Produced by NK cells and T cells that have been activated by detection of foreign materials; help macrophages to resist viral infection and attack virus-infected cells Inflammatory Response • promotes repair of damaged tissue • histamines and prostaglandins released • symptoms – heat – redness – swelling – pain The Development of Inflammation • tissue damage occurs • intracellular contents are released from damaged cells into interstitial fluid • mast cells release histamine and other inflammatory chemicals • blood vessels dilate, blood flow increases, capillary permeability increases • clot formation occurs • scar tissue forms, replacement cells grow Fever • maintenance of higher than normal body temperature • activation of leukocytes and macrophages causes release of pyrogens • hypothalamus raises body temperature, causing a fever Review and Assessment True or False? 1. Interferon is released by virus infected cells. 2. Pyrogens cause fever. 3. Neutrophils are not phagocytes. 4. Mucous membranes are a physical barrier. 5. Perforins engulf cells. Chapter 12: The Lymphatic and Immune Systems Lesson 12.3 Specific Defenses Specific Defenses – Immune System • called the specific immune system or adaptive immune system • Specific in its responses, recognizes new challenges, adapts to those challenges, and remembers what it has learned – antigens – immune system cells – humoral immunity – primary and secondary immune responses – cellular immunity Antigens • on the surface of cells – proteins – polysaccharides – glycolipids – nucleic acids • determine “self” from “nonself” cells Immune System Cells • antigen-presenting cells (APCs) – Macrophages, dendritic cells (immune cells in the skin and lymphatic organs, and B cells • lymphocytes – – – – develop from stem cells in the red bone marrow recognize only one antigen circulate continuously or settle down in the lymph nodes clonal selection: after a lymphocyte binds with its antigen it begins to make exact copies of itself – memory cells: clones that reside in lymphatic tissue, ready to respond if the same antigen re-enters the body Immune System Cells • MHC proteins (major histocompatibility complex glycoproteins) – presented on surface of cells – class I: found on all cells that contain nuclei – class II: found only on the surfaces of APCs Humoral Immunity • called antibody-mediated immunity – – – – – B cell binds with an antigen undergoes clonal selection Presents the antigen to a helper T cell T cell releases interleukins to stimulate an immune response activates the B cell • plasma cells – Daughter cells from clonal selection – make large quantities of antibodies in the rough endoplasmic reticulum – antibodies recognize and bind to specific antigen • antibodies – also called immunoglobulins – recognize, bind to, and mark antigens – interfere with antigen function Antibody Classes Humoral Immunity • https://www.youtube.com/watch?v=dTb 0iEUS1oA Primary and Secondary Immune Responses • primary immune response – when first exposed – neither fast nor widespread • secondary immune response – second or subsequent invasion – memory cells respond to invader Primary and Secondary Immune Responses Primary and Secondary Immune Responses • active immunity – antibody-mediated immunity from invasion • passive immunity – antibody-mediated immunity from antibodies received from an outside source • vaccination • breast feeding Cellular Immunity • facilitated or assisted by T cells • directed at cells (bacterial infected, viral infected, cancerous or precancerous cells) • fully activated cytotoxic T cells divide repeatedly, producing – active cytotoxic T cells: seek and destroy – memory cytotoxic T cells: prevents the cellular response from being too strong or too long – suppressor T cells: same as memory cT cells Cellular Immunity • Ways in which the cytotoxic T cells kill their targets – stimulate intracellular pathways that lead to apaptosis (programmed cell destruction) – releasing perforins that insert themselves into the target cell membrane and forming a large opening, or perforation, in the cell Cellular Immunity Review and Assessment Fill in the blanks with: antibodies, antigen, memory cells, or vaccination. 1. A(n) _______________ is passive immunity. 2. _______________ are also called immunoglobulins. 3. Lymphocytes recognize only one _______________. 4. _______________ are part of the secondary immune response. Chapter 12: The Lymphatic and Immune Systems Lesson 12.4 Disorders and Diseases of the Immune System Disorders and Diseases of the Immune System • • • • cancer and lymph nodes allergies autoimmune disorders HIV and AIDS Cancer and Lymph Nodes • rapid, unregulated cell growth • metastasis – cancerous cells move within body • cancerous cells may lodge in lymph nodes • biopsy and possible removal of lymph nodes • risk to lymphatic system with the removal of nodes – disrupts lymphatic drainage and fluid build-up in the interstitial fluid (lymphedema) Allergies • 55% of Americans have an allergy to one or more substances in the environment • inappropriately strong response to a harmless environmental antigen • exposure to allergen causes mast cells to release histamine • histamine causes an inflammatory response to the allergen – runny nose, itchy eyes, anaphylaxis Allergies • Anaphylaxis – pulmonary obstruction due to inflammation and swelling of the airways and low blood pressure due to leakage of blood plasma into the interstitial space – Treated with an injection of epinepherine and antihistamines • Immunotherapy – allergy shots Allergies Autoimmune Disorders • immune system attacks own body • cause unclear • More than 80 different types have been identified • examples – rheumatoid arthritis: attacks the synovial membrane that lines the joint cavity – multiple sclerosis: attacks the myelin sheath that surrounds the nerve cells – type I diabetes: attacks the alpha and beta cells of the pancreas HIV and AIDS • HIV (human immunodeficiency virus) – infects and kills helper T cells • AIDS (aquired immune deficiency syndrome) • Transmitted sexually, through sharing needles, mother to child during pregnancy or breastfeeding – helper T cell count falls below 200/mm3 – immune system seriously weakened – patient is susceptible to opportunistic infection Review and Assessment Match these words with 1–4 below: metastasis, autoimmune disorder, HIV, cancer. 1. rapid, unregulated cell growth 2. cancerous cells move within the body 3. rheumatoid arthritis 4. infects and kills T cells