RK Goit, Lecturer       Department of PhysiologyNepalgunj Medical College, Nepal
Reticuloendothelial system• phagocytosis   – ingestion of microbes or foreign cells or solid materials by a phagocyte• pha...
Macrophages (Kupffer cells) in the liver sinusoids bacteria from ingested food pass through GIT into the portal blood     ...
Alveolar macrophages in the lungs• organisms enter the body  through the lungs• macrophages can phagocytize particles   1....
Microglia of brain• microglia cells in brain & spinal cord appear to be inactive• in inflammatory disease of the CNS, they...
Tissue macrophages in the lymph nodes• if the particles are not destroyed locally in the tissues,  they enter the lymph & ...
Tissue macrophages in the spleen & bone• if an invading organism succeeds in entering the general  circulation, there are ...
Mesangial cells in kidney• are an unusual example of phagocytic cells derived  from smooth muscle & not monocytes• aid neu...
Tissue macrophages in the skin & subcutaneous tissues (Histiocytes)• when infection begins in a  subcutaneous tissue &  lo...
1. Phagocytic function  –    when any foreign body invades, macrophages ingest them by       phagocytosis & liberate the a...
4. Secretion of tumor necrosis factors  –   TNF-α: causes necrosis of tumor & activates the immune      responses in the b...
7. Removal of carbon particles & silicon  –   ingest the substances like carbon dust particles & silicon      which enter ...
Functions of spleen• Formation of blood cells   – play in important role in the hemopoietic function in embryo   – during ...
• Reservoir function   – a large number of RBCs are stored in spleen   – RBCs are released form spleen into circulation du...
Functions of lymph nodesLymph nodes serve as filters which filter bacteria & toxicsubstances form the lymph.• when lymph p...
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Functions of spleen and lymph nodes
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

  1. 1. RK Goit, Lecturer Department of PhysiologyNepalgunj Medical College, Nepal
  2. 2. 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.
  3. 3. 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
  4. 4. 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
  5. 5. 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
  6. 6. 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
  7. 7. Tissue macrophages in the spleen & bone• if an invading organism succeeds in entering the general circulation, there are other lines of defense
  8. 8. 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
  9. 9. 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
  10. 10. 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
  11. 11. 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
  12. 12. 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’
  13. 13. 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
  14. 14. • 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
  15. 15. 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
  16. 16. Thank You

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