Lecture 10
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Monocytes exit the blood to become macrophages. They make up 2-6% of white blood cells and are phagocytic, defending against viruses and bacteria. Monocytes live for 10-20 hours in the blood and then become tissue macrophages in the tissues. Macrophages are important phagocytes that destroy invading bacteria and viruses through phagocytosis and by releasing oxidizing agents. They are found in tissues throughout the body, including the skin, lymph nodes, lungs, liver, spleen, and bone marrow, where they phagocytose foreign particles and pathogens.
Lecture 10
- 1. 4. MONOCYTES * Exit blood (diapedesis) to become macrophages * 2-6 % of the WBC's * Phagocytic = defend against viruses and bacteria
- 2. Life span of WBC The life of granulocytes is normally 4 to 8 hours in the blood and another 4 – 5 days in tissue where they needed The monocytes 10 – 20 hours in the blood and in the tissues they become larger size and become tissue macrophage Lymphocytes have life span weeks or months depends on the needs
- 3. Leukocyte Leukocyte (WBC) are the mobile units of the body protective system They are formed in the bone marrow (granulocytes and monocytes and few lymphocytes) and in the lymph tissue (lymphocytes) Leukocytes work in two ways to prevent disease Destroying invading bacteria/viruses by phagocytosis By forming antibodies
- 4. Five types of WBC Three types of the cells are polymorphonuclear cells. All have granular appearance The granulocyte and monocytes protect the body against invading organism by phagocytosis Leukocyte
- 5. Human being has about 7000 WBC /micro liter Normal percentage are Neutrophils 62% Eosinphils 2.3% Basophils 0.4% Monocytes 5.3% Lymphocytes 30% Leukocyte
- 6. Neutrophils and Monocytes (macrophages) attack the invading bacteria, viruses WBC can squeeze through the blood capillaries by diapedesis WBC can move by ameboid motion WBC are attracted to inflamed tissue area by Chemotaxis Leukocyte
- 7. Phagocytosis which means cellular ingestion of the offending agent Macrophages are much more powerful phagocytes than neutrophils Lysosome in the neutrophil and macrophage come in contact with the phagocytic vesicle and digestion of phagocytized particles begin Both neutrophils and macrophages contain proteolytic enzyme. The lysosome in the macrophages contain lipases Leukocyte
- 8. Neutrophils and macrophages kill bacteria Neutrophils and macrophages contains oxidizing agent such as H 2 O 2 which is lethal to most bacteria
- 9. Monocyte-Macrophage Cell System The combination of monocytes, mobile macrophages, fixed tissue macrophages and specialized endothelial cells in the bone marrow, spleen and lymph nodes is called Monocyte-Macrophage cell system or reticuloendothelial system
- 10. Tissue macrophage in the skin Once the skin broken, infection occur and inflammation ensues Macrophages in subcutaneous tissue (Histiocyte) destroy the infectious agent by performing phagocytosis
- 11. Macrophages in the lymph nodes Large numbers of macrophages line the lymph sinuses and if any particles enter the sinuses the macrophages phagocytize them
- 12. Alveolar macrophages in the lungs Invading organisms enter the body through the lungs Tissue macrophages are present as integral components of alveolar walls They can phagocytize particles that entrapped in the alveoli
- 13. Macrophages Kupffer cells in the liver sinusoids Bacteria invading the body from ingested food through gastrointestinal tract into the portal blood Blood passes through sinusoids of the liver which lined with tissue macrophages called Kupffer cells These cells form such an effective particulate filtration to prevent passing bacteria from the gastrointestinal tract to the blood circulation system
- 14. Macrophages of the spleen and bone marrow Macrophages of the spleen and bone marrow is another defense against organism that succeeded to enter the blood circulation
- 15. Inflammation is the body response to infection or injury. The functions of inflammation are to destroy or inactivate foreign invaders and to set stage for tissue repair Inflammation
- 16. Inflammation Vasodilation of the blood vessels with consequent excess blood flow Increased permeability of the capillaries allowing leakage of large quantity of fluid Often clotting of the fluid Migration of large numbers of granulocytes and monocytes into the tissue Swelling of the tissue cells Some products that cause these reaction are histamine, serotonin and prostaglandins
- 17. The first result of inflammation is to “wall-off” the area of injury from the remaining tissue. The intensity of the inflammatory process is proportional to the degree Staphylococci release lethal toxins Inflammation Rapid Wall Off Streptococci no tissue destruction Inflammation Slow Wall Off Effect of inflammation “walling-off”
- 18. Within few minutes after inflammation begins, tissue macrophages begins their phagocytic action. Many fixed tissue macrophages break loose from their attachment forming the first line of defense against infection Macrophage and Neutrophil Responses During Inflammation
- 19. Neutrophil invasion of the inflamed area is the second line of defense Neutrophils begins to invade the inflamed area from the blood This is caused by products from the inflamed area which initiate the following reactions: Alter the inside surface of the capillary causing neutrophils stick on the capillary walls. This called margination Caused intracellular attachment to loosen diapedesis Other product caused chemotaxis Macrophage and Neutrophil Responses During Inflammation
- 20. Second macrophages invasion is a third line of defense Monocyte from the blood enter the inflamed tissues and enlarged to become macrophages Macrophages can phagocytize more bacteria larger particles than neutrophils Macrophage and Neutrophil Responses During Inflammation
- 21. Increased production of granulocytes and monocytes by bone marrow is the fourth line of defense Macrophage and Neutrophil Responses During Inflammation