lecture 3- chronic inflammation and healing Flashcards
In chronic inflammation which processes may be occurring simultaneously
active inflammation, extensive tissue destruction, and attempts at repair.
Granuloma formation
seen in tuberculosis and small number of other diseases.
core of necrosis. microscopic aggregations of macrophages that are transformed into epithelium-like cells. a collar of lymphocytes surrounds these. often macrophages fuse together into giant cells that have 20 or more nuclei. they can ingest a large foreign body.
Healing process- cleaning up the mess generate by the original injury and subsequent inflame response.
two parts.
ideally exudate is removed by macrophages. if its too great for macrophages to clean up repair occurs concerting mess generated by injury into viable tissue. organisation occurs where macrophages secrete growth factors (fibroblast growth factor, vascular endothelial growth factor). promote ingrowth of fibroblasts to lay down collagen and endothelial cells to form new vessels. once containing these it is granulation tissue. granulation tissue is reorganised into a fibrous scar. this may hinder remaining functional tissue.
Healing process- rebuilding the structure and function of the tissue that were destroyed by the injury and by the subsequent inflammatory response
mix of regeneration and repair.
while the mess is being cleared up attempts may be made to replace the parenchymal cells (functional cells of a tissue) within the tissue that have been destroyed. replacement is known as regeneration.
involves proliferation of stem cells from within the tissue and bone marrow. commonly seen in skin and gut.
The eventual outcome of tissue injury ranges between two extremes:
A fibrous scar in which the tissues original function is lost. and complete resolution in which the original structure and function is recovered by a combination of regeneration with complete removal of the mess left by injury and inflammation.
