Inflammation: Inflammation is a complex reaction of living vascularized tissue to injurious aget,leading to the exudation & accumulation of protein rich fluid and leucocytes in extravascular tissue. Classification of inflammation: 2 types of inflammation: 1)Acute inflammation. 2)Chronic inflammation. Cardinal signs of chronic inflammation: √Rubor(Redness):Due to vesodilatation( caused by histamin,serotonine,prostaglandin) √Tumor(swelling):Due to increase vascular permeability. Calor(heat):Due to compression of free nerve ending. Functio leasa(loss of function):Due to local pain and destruction. *Morphological features of acute inflammation: √Vascular changes: vesodilation and increase vascular permeability. √Oedema:Extravasation of plasma fluid and proteins in interstitial space. √Predominantly neutrophilic infiltration:Leucocyte emigration and accumulation at the site of injury. *Morphological features of chronic inflammation: Infiltration with mononeuclear cell,which include macrophage,lymphocyte and plasma cells. √Tissue destruction which is induced by persistent offending agent or by the inflammatory cells. √Attempt of healing. Causes of inflammation: a.Infection and microbial toxins:bacteria,viral and parasites. b.Physical agent: thermal injury. c.Chemical injury: Environmental chemical d.Tissue necrosis. e.Foreighn boddies. f.Immune reaction. Inflammatory cells are: Neutrophil, Macrophage, Eosinophil, Lymphocyt, Mast cell & plasma cells. Neutrophil: 1)Neutrophil phagocytosis and kills the ingested organism by intracellular killing mechanism. 2)Extracellular release of granules or cytotoxic granules. Macrophage: 1)Phagocytosis. 2)Presentation of antigen to helper T-cell. Eosinophil: 1)They also can phagocytes and kill the microorganism. 2)Eosinophil secretes histaminase which inactivate histamin released by basophil & mast cell. Mast cell: 1) Anaphylactic reaction(type-1hypersensitivity)by release of histamin. 2)May produce cytokines that contributes to fibrosis. Plasma cells: Production of antibodies. Fates or outcome of acute inflammation: 1)Complete resolution 2)Abscess formation. 3)Healing by connective tissue replacement. 4)Progression to chronic inflammation.