Lymphatic System Topics 1 2 3 4 5

Lymphatic System Topics 1. 2. 3. 4. 5. Components of the lymphatic system Functions of the lymphatic system Organization of lymphatic vessels Formation and flow of lymph Lymphatic organs

Flow of Lymphatic Capillaries Lymphatic Vessels Lymph Nodes Lymphatic Vessels Lymph Trunks Lymph Ducts Subclavian Veins

Formation of Lymph • Lymph is formed when interstitial fluid drains into lymph capillaries

Fig 21. 07

Figure 22. 4

Arteries Blood Capillaries Subclavian Veins Lymphatic Ducts Lymph Flow Interstitium Lymphatic Capillaries Lymph Trunks Lymph Nodes Lymphatic Vessels

Lymph Flow • Lymph flow aided by similar mechanisms as in the circulatory system: ü Milking action of skeletal muscle contractions ü Respiratory movements (pump) ü Valves that prevent backflow of lymph ü Vessel smooth muscle contraction

Lymph Drainage (Figure 22. 1) Good to Know…

Lymphatic System Topics 1. 2. 3. 4. 5. Components of the lymphatic system Functions of the lymphatic system Organization of lymphatic vessels Formation and flow of lymph Lymphatic organs

Lymphatic Organ Classification Primary Lymphatic Organs • Immunocompetency • Red bone marrow • Thymus Secondary Lymphatic Organs • Lymph nodes • Spleen • Lymphatic nodules ***

Thymus Gland Location • Mediastinum Structure • Bilobed; encapsulated; trabeculae (lobules) • Cortex and medulla • Contain T cells, dendritic and epithelial cells, macrophages Function • Site of T cell maturation (positive selection)

Figure 22. 5

Lymph Nodes Location • Along lymphatic vessels Structure • Encapsulated; oval; trabeculae (compartments) • Stroma and parenchyma (cortex + medulla) • Contain lymphocytes and other immune cells Functions • Receive lymph from afferent lymphatic vessels • Filter foreign substances out of lymph • Drain lymph into efferent lymphatic vessels

Figure 22. 6

Spleen Location • Left hypochondriac region between stomach’s fundus and diaphragm Structure • Encapsulated (Stroma) • Parenchyma: White pulp and Red pulp Functions • Next slide

Figure 22. 7

Spleen Functions • Receives blood from splenic artery • Phagocytoses pathogens • Mounts immune response against pathogens • Phagocytoses old blood cells • Stores blood platelets • Produces blood cells during fetal life

Lymphatic Nodules (Tissue) Locations • GI tract, respiratory airways, urinary tract, and reproductive tract • MALT (Peyer’s patches, tonsils, appendix) Structure • Unencapsulated; oval Function • “Sentinels” • Mount immune response against foreign substances

The organ that is NOT a secondary lymphatic organ is? a) b) c) d) Red bone marrow Spleen MALT Lymph nodes