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Published byMatthew Mathews Modified over 9 years ago
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THE LYMPHATIC SYSTEM Chapter 15
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Introduction Transports lymph through lymphatics Lymphatics: lymph capillaries and vessels Controls body fluid Destroys harmful microorganisms
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THE FUNCTIONS OF THE SYSTEM AND THE STRUCTURE AND FUNCTIONS OF THE LYMPHATIC VESSELS
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Introduction Drain interstitial fluid from tissue spaces –Prevent edema Transport digested fat to blood –Lacteals: special lymphatics in small intestine –Chyle: milky lymph in lacteals Develop immunities Produce lymphocytes
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Lymphatic Vessels Lymph capillaries: blind-end tubes Lymph capillaries are located between cells Lymph capillaries unite to form lymphatics Lymphatics converge into two main channels –Thoracic duct and right lymphatic duct
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Lymph Nodes Found along lengths of lymphatics Efferent: exit lymph node at the hilum Afferent: enter lymph node at various locations Trabeculae: divide the node into compartments
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Lymph Nodes (cont’d.) Germinal centers of compartments produce lymphocytes
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LYMPH CIRCULATION
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Lymph Circulation (cont’d.) Interstitial fluid: plasma in interstitial spaces Lymph: interstitial fluid in lymph capillaries –Passes into lymphatics Lymphatics join to form lymph trunks
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Lymph Circulation (cont’d.) Lymph circulation maintained by: –Normal skeletal muscle contractions Compresses lymph vessels and forces lymph in one direction –Respiratory or breathing movements –Smooth muscle in lymphatic vessels
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Lymph Circulation (cont’d.) Lymph trunks –Lumbar: drains lower extremities and pelvis –Intestinal: drains abdominal region –Bronchomediastinal and intercostal: drain thorax –Subclavian: drains upper extremities –Jugular: drains head and neck
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Lymph Circulation (cont’d.) Individual trunks drain into two main trunks –Thoracic duct: drains into the left subclavian vein –Right lymphatic duct: drains into the right subclavian vein
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THE ORGANS OF THE LYMPHATIC SYSTEM
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The Organs of the Lymphatic System (cont’d.) Tonsils –Palatine, pharyngeal and lingual –Protect the nose and oral cavity Thymus: lymphocyte production and maturation Peyer’s patches: found in walls of small intestine
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The Organs of the Lymphatic System (cont’d.) Spleen –Largest mass of lymphatic tissue –Phagocytizes worn-out RBCs and platelets Recycles hemoglobin –Produces lymphocytes and plasma cells –Stores blood for release during hemorrhage
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The Organs of the Lymphatic System (cont’d.) External view of the Spleen
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IMMUNITY
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Immunity (cont’d.) Ability of body to resist –Infection from pathogens –Damage from foreign substances and harmful chemicals
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Immunity (cont’d.) Humoral immunity –B lymphocytes: produce antibodies Fight circulating bacteria and viral infections Become plasma cells when they enter tissues
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Immunity (cont’d.) Cellular immunity –T lymphocytes Come from thymus glands Fight intracellular viruses, fungi, parasites, cancer
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ANTIGENS AND ANTIBODIES
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Antigens and Antibodies (cont’d.) Antigen: foreign protein in our body B lymphocytes –Produce antibodies in response to antigens –Antibodies bind to specific antigen –Antigens precipitate –Phagocytic WBCs eat the antigens
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Antigens and Antibodies (cont’d.) Antibody morphology –Four amino acid chains linked by disulfide bonds Heavy and light chains –Y shaped molecule –Binding sites at tips of Y –Stem of the Y is always constant
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Antigens and Antibodies (cont’d.) Antibody types –IgG: attacks viruses, bacteria, and toxins; activates complement –IgA: found in exocrine gland secretions –IgM: response to bacteria or food antigens –IgD: found on surface of B lymphocytes –IgE: associated with allergic reactions
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Antigens and Antibodies (cont’d.) Active immunity: B cells contact antigen and produce antibodies –Natural active: exposure to infection –Artificial active: vaccine Passive immunity –Natural passive: maternal antibodies to fetus –Artificial passive: gamma globulin
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CELLS OF THE IMMUNE RESPONSE AND OTHER DEFENSES
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Cells of the Immune Response and Other Defenses (cont’d.) B cells: antigen –Antibody binding Plasma cells: replicated B cells Helper T cells: stimulate production of –Killer T cells –More B cells
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Cells of the Immune Response and Other Defenses (cont’d.) Killer T cells: –Attack virus-invaded body cells –Attack cancer cells –Reject body grafts Memory cells: descendants of activated T and B cells
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Cells of the Immune Response and Other Defenses (cont’d.) Suppressor T cells: slow down activities of B and T cells Macrophages –Engulf and digest antigen –Present then to T cell for recognition Lymphokines: chemicals released by sensitized T cells
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Cells of the Immune Response and Other Defenses (cont’d.) Monokines: chemicals released by activated macrophages Skin: mechanical barrier –Acid mantle, sebum Lysozyme: (tears and saliva) attacks bacteria
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Cells of the Immune Response and Other Defenses (cont’d.) Mucous membranes: trap microorganisms and debris Hydrochloric acid: (stomach) destroys microorganisms
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Animation – Lymphatic System Click Here to Play Lymphatic System Animation
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Summary Discussed the functions of the immune system Described lymph and its flow through the body Discussed the functions of the spleen and tonsils
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Summary (cont’d.) Described the different types of immunity Discussed the immune response
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