6. Chronic Inflammation Flashcards
what is the purpose of inflammation?
- remove the cause of injury
- initiate repair
- prevent necrosis
what are the dominant cells in chronic inflammation?
lymphocytes, macrophages and plasma cells
granulation and scar tissue is more abundant
does chronic inflammation have a primary or secondary onset?
usually primary, but can be sequential from acute inflammation
what are the factors precipitating chronic inflammation?
- infection - TB, leprosy, viruses
- endogenous materials - uric acid crystals
- exogenous materials - asbestos, sutures, implants
- autoimmune - RA, SLE
- primary granulomatous diseases - crohn’s, sarcoidosis
when does chronic inflammation have a secondary onset?
most common in suppurative acute inflammation
if the abscess is deep enough, the walls thicken, cause granulation and fibrous tissue.
recurrent acute inflammations also lead to chronic
what are the morphological features of chronic inflammation?
infiltration with mononuclear cells
tissue destruction
healing by fibrosis
what is a granuloma?
mass of immune cells that forms at sites of infection or inflammation
what are the macroscopic features of chronic inflammation?
dependent on the actual disease
chronic abscess cavity
granulomatous in some cases
fibrosis
what are the microscopic features of chronic inflammation?
- cellular infiltrate of lymphocytes, plasma cells and macrophages
- exudation if fluid is not prominent
- production of new fibrous tissue from granulation tissue
what is the function of macrophages?
phagocytosis of bacteria and damaged tissue
what are the 3 processes involved in wound healing?
- angiogenesis
- deposition of collagen by fibroblasts
- inflammatory cells
what is the aim of wound healing?
to replace injured tissue with fibrous tissue
what is fibrosis?
macrophage induced laying down of connective tissue including collagen during repair of damaged tissue
what are histiocytic cells?
multinuclear giant cells which develop when 2 or more macrophages try to engulf the same particle
no known function
what are the histological contents of a granuloma?
langerhans giant cells + epithelioid histiocytes + caseous necrosis
