The Lymph System and Lymphoid Organs and Tissues

1. The Lymph System and Lymphoid Organs and Tissues

2. Overview • lymphatic vessels • lymph • lyphoid cells and tissues • lymphoid organs • lymph nodes • spleen • thymus • tonsils • other lymphoid tissue

3. lymphatic vessels • collects excess interstitial fluid • returns fluid to blood • one way system • flows toward the heart

4. lymphatic vessels lymphatic capillaries - cells overlap - collagen filaments anchor ends

5. lymphatic vessels lacteals - specialized lymph capillaries in lining of small intestine - absorb fats - chyle = fatty lymph that is milky white - moves into lymph vessels

6. lymphatic vessels lymphatic collecting vessels - similar structure to veins - more valves - reconnect (anastamose) more often

7. lymphatic vessels lymphatic trunks - formed by union of largest vessels

8. lymphatic vessels lymphatic ducts - right - thoracic - cisterna chyli - enlarged sac where lumbar trunks meet

9. lymphatic vessels • lyphangitis • when lymph vessel is inflamed, blood vessels that feed them become congested with blood

10. lymph - similar to blood plasma - white blood cells - debris/pathogens

11. lymph transport • no pump • skeletal muscles • muscles used to breathe • diaphragm • intercostal muscles • smooth muscle in lymphatic trunks and thoracic duct • valves prevent backflow • arterial pumping

12. lymph transport • lymphedema • flow is blocked • lymph vessels removed • lymph vessels can regrow!

13. lymphoid cells • lymphocytes • T cells • B cells • macrophages • dendritic cells • reticular cells

14. lymphoid tissue • houses and provides a site for proliferation of lymphocytes • surveillance point for lymphocytes and macrophages

15. lymphoid tissue types • diffuse • found in every body organ • scattered • lymphoid follicles • solid spherical bodies • germinal center

16. lymph nodes • clusters • - inguinal • - axillary • - cervical • functions • - filter lymph • - help activate the immune system

17. lymph nodes - average 1" bean shaped - capsule with trabeculae - cortex - medulla

18. lymph nodes flow through node - afferent lymph vessels - efferent lymph vessels

19. spleen • size of fist • largest lymphoid organ • site of lymphocyte proliferation • site of immune surveillance

20. spleen • cleans the blood • stores and releases breakdown products of RBCs • stores blood platelets • site of RBC production in fetus

21. spleen

22. spleen

23. thymus

24. thymus • many thymic lobules • cortex • rapidly dividing lymphocytes • medulla • thymic corpuscles • development of regulatory T cells • prevent autoimmune diseases

25. tonsils • palatine tonsils • lingual tonsil • pharyngeal tonsil • tubal tonsils

26. tonsils tonsillar crypt

27. other lymphoid tissue Peyer's patches - aggregated follicles in the far end of the ileum and appendix - immune function of GI tract

28. other lymphoid tissue MALT - mucosa-associated lymphatic tissue - Peyer's patches - appendix - tonsils - lymphoid follicles in bronchi - lymphoid follicles in genitourinary organs