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The Lymphatic System

The Lymphatic System. Anatomy & Physiology. Lymphatic System-General. 2 Main Parts Lymphatic vessels Lymphoid tissues/organs FUNCTIONS: Drain excess fluid (edema) and returns it to blood Plays essential roles in body defense and resistance to disease. Lymphatic System-General.

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The Lymphatic System

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  1. The Lymphatic System Anatomy & Physiology

  2. Lymphatic System-General • 2 Main Parts • Lymphatic vessels • Lymphoid tissues/organs • FUNCTIONS: • Drain excess fluid (edema) and returns it to blood • Plays essential roles in body defense and resistance to disease

  3. Lymphatic System-General • Lymph—excess tissue fluid • Properties of lymphatic vessels • One way system toward the heart • No pump • Lymph moves toward the heart • Transported through milking action of skeletal muscle • Rhythmic contraction of smooth muscle in vessel walls helps pump the lymph through the system

  4. Relationship of Lymphatic Vessels to Blood Vessels

  5. Lymphatic Vessels • Lymph capillaries • Walls overlap to form flap-like minivalves to allow entrance for lymph • Fluid leaks into lymph capillaries • Lymph Capillaries are anchored to connective tissue by filaments • Higher pressure on the inside of the capillary closes minivalves • Fluid is forced along the vessel for examination • Examined by cells of immune system for any potential threats

  6. Lymphatic Vessels • Lymphatic collecting vessels • Collect lymph from lymph capillaries • Carry lymph to and away from lymph nodes • Return fluid to circulatory veins near the heart • Right lymphatic duct • Drains lymph to right arm/head/thorax • Thoracic duct • Drains rest of body that R.Lymphduct doesn’t

  7. Lymph • Harmful materials that enter lymph vessels • Bacteria • Viruses • Cancer cells • Cell debris

  8. Lymph Nodes • Filter lymph before it is returned to the blood • Areas of high concentration? • Inguinal, axillary, and cervical regions • Defensecells within lymph nodes • Macrophages—engulf and destroy foreign substances • Lymphocytes—provide immune response to antigens • Nodes swell when fighting infection because nodes have engulfed the foreign substance to prevent it from spreading

  9. Lymph Node Structure • Most are kidney-shaped and less than 1 inch long • Cortex • Outer part • Contains follicles—collections of lymphocytes • Medulla • Inner part • Contains phagocytic macrophages

  10. Other Lymphoid Organs • Several other organs contribute to lymphatic function • Spleen • Thymus • Tonsils • Peyer’s patches

  11. Spleen • Blood filled organ which filters blood • Location: Left side of abdomen above diaphragm • Functions: • Filters/cleanses blood of foreign substances • Destroy worn-out blood cells • Recycles components of worn out blood cells (i.e. hemoglobin) • Stores platelets • Protect body during hemorrhage

  12. Thymus Gland • Lymphoid mass found in throat • Function: Programs lymphocytes with the help of thymosin (hormone)

  13. Tonsils • Small, lymphoid tissue in back of throat • Function: Capture and remove any foreign pathogens(substances) • Reason they become swollen during colds/viruses

  14. Peyer’s Patches • Location: Wall of small intestine • Function: Capture and destroy bacteria • Prevent foreign pathogens from penetrating intestinal wall

  15. Body Defenses • The body is constantly in contact with bacteria, fungi, and viruses • The body has two defense systems for foreign materials • Innate (nonspecific) defensesystem • Attacks ANY foreign pathogen • Adaptive (specific) defensesystem • Attacks SPECIFIC substances • Immunity—specific resistance to disease • -Immun=free

  16. Immune System

  17. Innate Body Defenses • AKA “non-specific defense system” • Innate body defenses are mechanical barriers to pathogens such as • Body surface coverings • Intact skin • Mucous membranes • Line all body cavities that are exposed (i.e. digestive, respiratory, urinary, and reproductive tracts) • Specialized human cells • Chemicals produced by the body

  18. Surface Membrane Barriers:First Line of Defense • Skin and mucous membranes • Physical barrier to foreign materials • Also provide protective secretions • pH of the skin is acidic to inhibit bacterial growth • Sebum is toxic to bacteria • Stomach releases hydrochloric acid to kill pathogens • Saliva and lacrimal fluid contain lysozymes which kill bacteria • Mucus traps microorganisms and prevent them from entering the digestive or respiratory tract

  19. Cells and Chemicals:Second Line of Defense • Phagocytes • I.e. macrophage or neutrophil • Swallows foreign pathogen • Natural killer cells • Kill cancer and virus cells • Fight off these pathogens by detecting sugar molecules on pathogen’s surface

  20. Cells and Chemicals:Second Line of Defense Cont’d • Inflammatory response • Happens when tissue is injured • 4 signs: Redness, heat, inflammation, swelling pain • Histamine & Kinins causes: • Vessels to dilate causing inflammation • Activate pain receptors to alert body of problem • Attract WBCs and phagocytes to clean cellular debris from tissue damage

  21. Cells and Chemicals:Second Line of Defense Cont’d • Antimicrobial proteins • Fever

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