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Inflammation, role and types.


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Inflammation is a fundamental process for human survival, this lecture covers the basics of the process, its components and affects. Developing an understanding of this process will enable the student to comprehend this omnipresent process and how it is directly linked to our survival.

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Inflammation, role and types.

  1. 1. INFLAMMATION get in touch Dr. Ali Yaldrum B.D.S, M.Sc (London) Faculty of Dentistry, SEGi University
  2. 2. Survival of all organisms requires they eliminate: • foreign invaders (infectious pathogens: viruses, bacteria, fungi) • damaged tissues • Achieved via a complex mechanism called “inflammation”
  3. 3. Inflammation is a protective response intended to eliminate the initial cause of cell injury as well as the necrotic cells and tissues resulting from the original insult
  4. 4. Diluting Destroying/ Neutralising Heal & Repair Restoration of Function
  5. 5. A double edge sword? Although inflammation helps clear infections and other noxious stimuli and initiates repair, the inflammatory reaction and the subsequent repair process can cause considerable harm.
  6. 6. Signs of Inflammation Cardinal signs are • Heat (calor) • Redness (rubor) • Swelling (tumor)
  7. 7. 2 additional signs seen in acute inflammation • Pain (dolor) • Loss of function (function laesa)
  8. 8. Steps of Inflammation 5R’s 1. Recognition of injurious agent 2. Recruitment of leukocytes 3. Removal of agent 4. Regulation of the response 5. Resolution
  9. 9. Types of Inflammation • Acute • Chronic
  10. 10. Acute Inflammation
  11. 11. Acute Inflammation rapid response to injury or microbes and other foreign substances that is designed to deliver leukocytes and plasma proteins to sites of injury
  12. 12. Stimuli can be triggered by a variety of stimuli • Infections • Trauma • Physical & chemical agents • Foreign bodies • Immune reactions
  13. 13. Acute inflammation has two major components • Vascular changes • Cellular events
  14. 14. Vascular • Changes in Vascular Caliber and Flow • Increased Vascular Permeability
  15. 15. Changes in Vascular Caliber and Flow • Changes in blood vessels begin rapidly after infection or injury but may develop at variable rates, depending on the nature and severity of the original inflammatory stimulus.
  16. 16. transient vasoconstriction arteriolar vasodilation increased viscosity & slowing of circulation stasis migration lasting few seconds
  17. 17. • Endothelial cell contraction leads to intercellular gaps in post capillary venules
  18. 18. • Histamine, bradykinin, leukotrines • immediate • short lived 15 to 30 mins • called as immediate transient response
  19. 19. • IL1 and TNF • prolonged changes in cytoskeleton of endothelial cells • take 4-6 hours to develop • lasts for up to 24 hours
  20. 20. Cellular Events • an important function of the inflammatory response is to deliver leukocytes to the site of injury and to activate them
  21. 21. Leukocyte recruitment Sequence consists of: 1. margination, adhesion to endothelium & rolling along the vessel wall 2. firm adhesion to endothelium
  22. 22. 3. transmigration between endothelial cells; 4. migration in interstitial tissues toward a chemotactic stimulus
  23. 23. Leukocyte activation • Once leukocytes have been recruited to the site of infection or tissue necrosis, they must be activated to perform their functions
  24. 24. • Stimuli for activation include microbes, products of necrotic cells, and several mediators
  25. 25. Phagocytosis Consists of 3 distinct but interrelated steps 1. recognition and attachment of the particle to the ingesting leukocyte 2. engulfment, with subsequent formation of a phagocytic vacuole 3. killing and degradation of the ingested material.
  26. 26. Patterns of acute inflammation
  27. 27. Patterns of acute inflammation • vascular and cellular reactions that characterize acute inflammation are reflected in the morphologic appearance of the reaction
  28. 28. • serous inflammation • fibrinous inflammation • suppurative inflammation
  29. 29. serous characterized by: • the outpouring of a watery • relatively protein-poor fluid that, depending on the site of injury
  30. 30. fibrinous • occurs as a consequence of more severe injuries, • resulting in greater vascular permeability that allows large molecules (such as fibrinogen) to pass the endothelial barrier
  31. 31. suppurative • manifested by the presence of large amounts of purulent exudate (pus) consisting of neutrophils, necrotic cells, and edema fluid
  32. 32. • Abscesses are focal collections of pus that may be caused by seeding of pyogenic organisms into a tissue or by secondary infections of necrotic foci.
  33. 33. Chemical mediators of inflammation
  34. 34. Chemical mediators of inflammation • Mediators may be produced locally by cells at the site of inflammation, • or may be circulating in the plasma as inactive precursors that are activated at the site of inflammation
  35. 35. Chronic Inflammation
  36. 36. Chronic Inflammation • is inflammation of prolonged duration (weeks to months to years) in which active inflammation, tissue injury, and healing proceed simultaneously.
  37. 37. Characterized by: • infiltration with mononuclear cells • plasma cells tissue destruction • repair • angiogenesis • fibrosis
  38. 38. When acute inflammation converts to chronic?
  39. 39. Chronic inflammation arises in the following settings: 1. T lymphocyte-mediated immune r e s p o n s e c a l l e d d e l a y e d - t y p e hypersensitivity 2. Immune-mediated inflammatory diseases 3. autoimmune diseases
  40. 40. Chronic Inflammatory Cells and Mediators • fundamental feature of chronic inflammation is its persistence • results from complex interactions between the cells that are recruited to the site of inflammation and are activated at this site
  41. 41. Macrophages • dominant cell of chronic inflammation • derived from circulating blood monocytes • act as filters for particulate matter, microbes, and senescent cells, as well as acting as sentinels
  42. 42. • scattered in most connective tissues, • also found in organs such as the liver • spleen and lymph nodes • central nervous system • lungs
  43. 43. • Together these cells comprise the so- called mononuclear phagocyte system, also known by the older name of reticulo- endothelial system
  44. 44. Lymphocytes • mobilized to the setting of any specific immune stimulus • as well as non-immune-mediated inflammation
  45. 45. Eosinophils • characteristically found in inflammatory sites around parasitic infections • or as part of immune reactions mediated by IgE, typically associated with allergies.
  46. 46. Mast cells • sentinel cells widely distributed in connective tissues throughout the body, • participate in both acute and chronic inflammatory responses • "armed" with IgE antibody specific for certain environmental antigens
  47. 47. • Neutrophils are the classic hallmarks of acute inflammation, many forms of chronic inflammation may nevertheless continue to show extensive neutrophilic infiltrates
  48. 48. References • Robins, Basic Pathology, 8th Edition.