Functions of spleen and lymph nodes
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Functions of spleen and lymph nodes

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Functions of spleen and lymph nodes Functions of spleen and lymph nodes Presentation Transcript

  • RK Goit, Lecturer Department of PhysiologyNepalgunj Medical College, Nepal
  • Reticuloendothelial system• phagocytosis – ingestion of microbes or foreign cells or solid materials by a phagocyte• phagocytes are neutrophils, monocytes & macrophages• monocytes transform themselves into macrophages in tissue• these macrophages are mononuclear cells, & this system of phagocytes is called as mononuclear phagocyte system (MPS)• this system of cells was known as reticuloendothelial system – neither they are reticular in appearance – nor they have endothelial origin• Therefore, the term reticuloendothelial system is obsolete.
  • Macrophages (Kupffer cells) in the liver sinusoids bacteria from ingested food pass through GIT into the portal blood ↓ it passes through the sinusoids of the liver ↓ these sinusoids are lined with Kupffer cells ↓ these cells form an effective particulate filtration system
  • Alveolar macrophages in the lungs• organisms enter the body through the lungs• macrophages can phagocytize particles 1. if the particles are digestible, the macrophages can digest them & release the digestive products into the lymph 2. if the particle is not digestible, the macrophages often form a “giant cell” capsule around the particle→ slowly dissolve
  • Microglia of brain• microglia cells in brain & spinal cord appear to be inactive• in inflammatory disease of the CNS, they become the immune effector cells• they proliferate & become antigen presenting cells
  • Tissue macrophages in the lymph nodes• if the particles are not destroyed locally in the tissues, they enter the lymph & flow to the lymph nodes• foreign particles are then trapped in these nodes in a meshwork of sinuses lined by tissue macrophages
  • Tissue macrophages in the spleen & bone• if an invading organism succeeds in entering the general circulation, there are other lines of defense
  • Mesangial cells in kidney• are an unusual example of phagocytic cells derived from smooth muscle & not monocytes• aid neutrophils in removing other mesangial cells undergoing apoptosis & also other debris in glomerulus
  • Tissue macrophages in the skin & subcutaneous tissues (Histiocytes)• when infection begins in a subcutaneous tissue & local inflammation ensues, local tissue macrophages can divide in situ & form still more macrophages• then they perform the usual functions of attacking & destroying the infectious agents
  • 1. Phagocytic function – when any foreign body invades, macrophages ingest them by phagocytosis & liberate the antigenic products of the organism – antigens activate the helper T lymphocytes & B lymphocytes2. Secretion of bactericidal agents – secrete many bactericidal agents which kill the bacteria I. Superoxide (O-2) II. Hydrogen peroxide (H2O2) III. Hydroxyl ions (-OH-)3. Secretion of interleukins – IL-1: accelerate maturation & proliferation of specific B lymphocytes & T lymphocytes – IL-6: cause growth of B lymphocytes – IL-12: influence the T-helper cells
  • 4. Secretion of tumor necrosis factors – TNF-α: causes necrosis of tumor & activates the immune responses in the body – TNF-β: stimulates immune system5. Secretion of platelet derived growth factor – accelerates repair of damaged blood vessel & wound healing6. Secretion of colony stimulation factor – M-CSF accelerates growth of granulocytes, monocytes & macrophages
  • 7. Removal of carbon particles & silicon – ingest the substances like carbon dust particles & silicon which enter the body8. Destruction of RBC – remove aged RBC9. Giant cell – 20 or more macrophages can fuse to form a multinucleate ‘giant cell’ that engulfs a bacillus10. Foam cells – macrophages store excess lipids & mucoprotein & become swollen to form ‘foam cells’
  • Functions of spleen• Formation of blood cells – play in important role in the hemopoietic function in embryo – during the hepatic stage, spleen produces the blood cells along with liver• Destruction of blood cells – the older RBCs, lymphocytes & thrombocytes are destroyed in the spleen
  • • Reservoir function – a large number of RBCs are stored in spleen – RBCs are released form spleen into circulation during the emergency conditions like hypoxia & hemorrhage• Role in defense of body – spleen filters the blood by removing the microorganism – macrophages in splenic pulp phagocytose the microorganism & other foreign bodies – spleen contains about 25% of T lymphocytes & 15% of B lymphocytes & form the site of antibody production
  • Functions of lymph nodesLymph nodes serve as filters which filter bacteria & toxicsubstances form the lymph.• when lymph passes through the lymph nodes, it is filtered i.e. the water & electrolytes are removed – but the proteins & lipids are retained in the lymph• bacteria & other toxic substances are destroyed by macrophages of lymph nodes
  • Thank You