Chronic Inflammation

• What happens after acute inflammation depends on?

  1) amount of tissue damage sustained 2) causative agent remains
• What happens when the causative agent is removed or destroyed?

  MPN exudate is replaced by a mononuclear one

  
• What are monocytes?

  Another type of phagocytic leukocyte. Migrate into tissues and develop into macrophages.
• Where do monocytes originate from?

  Monocytes originate in bone marrow where they have a generation life of about 24 hours
• How long do monocytes circulate in the blood for?

  1-3 days - leave the circulation to become tissue macrophages
• What is chemotaxis?

  movement of an organism in response to a chemical stimulus
• What is the demolition phase?

  Macrophages engulf fibrin, red cells, degenerate polymorphs, bacteria, etc. Scavengers

  
• What is meant by resolution?

  • Where cellular damage is slight, cellular tissue changes are reversible
  • Removal of the exudate via the lymphatics
  • The organ returns to normal
  • Resolution is the complete return to normal following acute inflammation
• Can inflammatory oedema endanger life?

  Yes - e.g larynx
• Can acute inflammation occur in avascular tissue?

  No - Acute inflammation is a vascular phenomenon and cannot occur in avascular tissue, such as cartilage or cornea.
• What are the three phases of tissue response to injury?

  1. The initial vascular and exudative phenomena of acute inflammation are followed by

  2. A phase of demolition

  3. Resolution or if tissue is lost, healing by repair and regeneration
• Complete healing can only occur when....

  - The acute inflammation and demolition phases are completed- initial cause of inflammation has to be removed
• What is Chronic Inflammation?

  If the tissue damage continues there is a mixture of acute inflammation, demolition, repair and regeneration
• What is the process in which destruction and inflammation are proceeding at the same time as attempts at healing?

  Chronic Inflammation
• True or False? Chronic inflammation follows when the causative agent is not removed e.g. gingivitis, periodontitis

  True
• What is Granulation tissue?

  Forms where there is attempt at healing

  New connective tissue that fills the injured area whilst the necrotic debris is removed
• What does granulation tissue consist of?

  • Fewer PMNs
  • Appearance of lymphocytes and plasma cells
  • Macrophages remain and in some cases giant cells form e.g. around dead bone
  • Proliferation of vascular epithelium by "budding" forming new capillaries (angiogenesis)
  • Proliferation of fibroblasts with collagen production (fibrosis)
• Why does bleeding occur in chronic gingivitis?

  Because granulation tissue is highly vascular and may give rise to hemorrhage
• How is granulation tissue formed?

  proliferation and migration of surrounding connective tissue elements

  
• What lays down collagen?

  Fibroblasts
• How is scar tissue formed?

  Lumina of small arteries and arterioles are obliterated by thickening of the tunica intima
• What is chronic gingivitis characterised by?

  Massive plasma cell infiltrate

  Plasma cells produce immunoglobulins

  Lymphocytes form a mobile reserve for other cells
• What is Regeneration?

  Where tissue is capable of division, regeneration rather than repair takes place E.g. epithelium, as seen in a chronic ulcer when the edges of the ulcer overgrow

  
• Flow chart of processes after cell damage?

  1. cell damage = acute inflammation = demolition phase

  EITHER

  2) cause of inflammation removed, resolution if no tissue lost and repair and regeneration if tissue lost

  2) cause of inflammation not removed = chronic inflammation = granulation tissue/scarring/repair/regeneration/acute inflammation
• What are the differences between acute and chronic inflammation?

  Acute: sudden onset, short duration, more pain, more redness, swelling (oedema), increases heat, increased loss of function

  
  

  Chronic: insidious onset, long duration, less pain/discomfort, less redness, swelling (granulation tissue), less heat, reduced loss of function
• Granulation Tissue?

  • new connective tissue and tiny blood vessels form on the surface of a wound during the healing process
  • type of fibrovascular proliferation
  • reddish, soft, moist and bumpy
  • usually painless
  • consists of new small blood vessels, fibroblasts, mononuclear cells
  • grows at base of wound, aiding healing