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Lymphatic System

Lymphatic System. Tissues, organs, vessels and a fluid called lymph similar to interstitial fluid Diffuse lymphatic tissue Tonsils, mucosa associated lymph tissue and red bone marrow Organs involved thymus spleen lymph nodes. Functions of the Lymphatic System.

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Lymphatic System

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  1. Lymphatic System • Tissues, organs, vessels and a fluid called lymph • similar to interstitial fluid • Diffuse lymphatic tissue • Tonsils, mucosa associated lymph tissue and red bone marrow • Organs involved • thymus • spleen • lymph nodes

  2. Functions of the Lymphatic System • Draining excess interstitial fluid & plasma proteins from tissue spaces • Transport of some nutrients and hormones • Immunity –specific defense • recognize microbes or abnormal cells & respond by killing them directly or secreting antibodies that cause their destruction

  3. Formation & Flow of Lymph • Fluid & proteins filtered from blood capillaries are collected by lymphatic capillaries & returned to the blood • Muscle contraction and breathing promote flow of lymph • Lymphatic vessels empty into veins in shoulders

  4. Lymph Circulation • Lymphatic capillaries • Capillaries are closed-ended tubes in tissues • One-way valves • Pickup fluid (lymph) from Tissues

  5. Lymph Circulation • LymphaticVessels • Lymph passes from capillaries into lymph vessels • Resemble veins with thin walls & valves • Afferrent lymphatics carry lymph to nodes • Efferent lymphatics carry lymph from nodes • Lymphatic Trunks • Lymph passes from lymphatic vessels into trunks • *Bronchomediastinal, jugular, subclavian, intestinal and lumbar trunks

  6. Lymph Circulation • Lymphatic ducts • Two ducts drain lymph from lymphatic trunks into the subclavian veins • Thoracic Duct: Larger one that drains most of body lymph into the left subclavian vein • Right Lymphatic Duct: Smaller one that drains right side of head, right shoulder and right arm into the right subclavian vein

  7. Lymph Circulation Right Lymphatic Duct------ --------------------Thoracic Duct Right Lymphatic Duct------ Thoracic Duct----------------------------

  8. Lymphatic Pathways Interstitial fluid  Lymph Capillaries  Afferent Lymphatic vessels  Lymph Nodes Efferent Lymphatic vessels  Lymphatic Trunks Lymphatic Ducts  Subclavian Veins

  9. Lymphocytes • B-cell lymphocytes • Respond to antigens by dividing to produce • Plasma cells: Antibody secreting cells • Memory B-cells • T-cell lymphocytes • Respond to antigens by dividing to produce • Cytotoxic T-cells that kill antigen-bearing cells • Helper T-cells that help activate other T-cells and B-cells • Memory T-cells • Natural killer (NK) lymphocytes can kill invading cells and tumor cells without need to respond to antigens – nonspecific defense

  10. Diffuse Lymphatic Tissues • Lymphatic nodules – MALT(Mucosa Associated Lymph Tissues) • lymphatic nodules within the digestive and respiratory systems • Small intestine -Peyer's patches • Appendix • Bronchi of respiratory tract

  11. Diffuse Lymphatic Tissues • Tonsils • Located in and around throat • Tonsilar crypts • Functions • Crypts Trap microbes • Mount immune response against inhaled and ingested microbes

  12. Lymph organs • Lymph nodes • Structure • Location • Throughout body but concentrated in groin, neck, armpit • Functions • Filter Lymph • Mount immune response

  13. Lymph Node Distribution

  14. Lymph Organs • Thymus • Located in mediastinum above heart • Large in infants atrophying with age • Function • Thymosin hormones for T-cell maturation

  15. Spleen • Located in upper left quadrant to left of stomach • Functions • Filters blood • Produces lymphocytes • Stores iron and platelets

  16. Defense • Non-specific Defense • First Line Defense: External • Skin • Mucous Membranes • Tears • Saliva • Stomach acid

  17. Non-specific Defense • Second Line Defense: Internal • Antimicrobial proteins • Interferons – antiviral • Complement – immunity, allergies and inflammation • Natural killer (NK) cells • Lymphocytes • kill microbes and tumor cells • Phagocytes • Wandering phagocytes • Fixed phagocytes

  18. Non-specific Defense • Second Line Defense: Internal • Inflammation • Mast cells and basophils release chemicals • Arterioles vasodilate – more blood to site • Increased capillary permeability – more fluid into tissues

  19. Non-specific Defense • Inflammation results in • Redness • Heat • Swelling (edema) • Pain • Healing

  20. Specific Defense: Immunnity • Study of immunity is immunology • Immunity versus non-specific defense • Specificity: responds to specific antigens • Memory: Second exposure to antigen causes a stronger response • Antigens • Foreign (non-self) chemicals • Cause immune response

  21. Immunity • B-cell and T-cell lymphocytes responsible for immunity • Two types of immune responses • Cell mediated immunity: T-cells respond to intracellular antigens such as virus infected cells and tumor cells • Antibody mediated immunity: B-cells respond to extracellular antigens such as bacteria

  22. Cell Mediated Immunity • T-cells processed by thymus gland • Two types of T-cell lymphocytes • CD4cells (Helper cells) • Activated when antigen presented by antigen presenting cell (APC) cell • Develops into helper T-cells and memory cells • Helper T-cells must stimulate CD8 cells for them to become fully activated killer T’s • CD8cells (Cytotoxic cells) • Activated by contact with virus infected body cell • Develop into killer t-cells and memory cells

  23. Cell Mediated Immunity • Cytotoxic T’s leave lymphatic tissue to search for and destroy virus infected cells, tumor cells and tissue transplant cells on contact

  24. Cell Mediated Immunity

  25. Antibody Mediated Immunity • B-cell lymphocytes stay in lymph tissues • Extracellular antigen enters lymph tissue and binds to B-cell receptors • B-cells become activated • B-cells divide (clone) to form plasma cells and memory cells • Helper T-cells bind to antigen on B-cells and “help” stimulate plasma cell and memory cell formation

  26. Antibody Mediated Immunity • Plasma cells secrete various types of antibodies • Antibodies bind to the specific antigen that activated its parent B-cells • Antibodies cause the destruction of the antigen

  27. Antibody Mediated Immunity • Antibodies destroy antigens by • Neutralizing antigens such as toxins • Agglutinating (clumping) and precipitating (removing from solution) antigen bearing cells • Activating the complement proteins that destroy the antigen by various means • Enhancing phagocytosis

  28. Antibody Mediate Immunity

  29. Immune Response Primary Response • After an initial exposure to an antigen a slow rise in antibodies production occur first as immunoglobulin M (IgM) then (IgG) Secondary Response • After a subsequent exposure the antibodies production is far greater and is mainly (IgG)

  30. Summary of Cell and Antibody Mediated Immunity

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