Acute And Chronic Inflammation PDF

The effects of acute inflammation depend on: ▪ ▪ ▪ Dr.Nazar Jawhar The outcome may be: ❖ Complete resolution: ❖ Scarring &fibrosis: ❖ Abscess formation: ❖ Progression to chronic inflammation: Dr.Nazar Jawhar Dr.Nazar...

The effects of acute inflammation depend on: ▪ ▪ ▪ Dr.Nazar Jawhar The outcome may be: ❖ Complete resolution: ❖ Scarring &fibrosis: ❖ Abscess formation: ❖ Progression to chronic inflammation: Dr.Nazar Jawhar Dr.Nazar Jawhar  ABSCESS: A localized collection of pus, which usually develops following extensive tissue damage especially that caused by pyogenic bacteria as staph aureus. PUS: A thick yellow viscous fluid resulting from the liquefaction of tissue due to the action of lysosomal enzymes. It contains dead & dying neutrophils, necrotic tissue debris, microorganisms & fluid component of acute Dr.Nazar Jawhar inflammation.  MORPHOLOGICAL FEATURES IN ACUTE INFLAMMATION: Depending on the type & severity of the injury & on the type of tissue affected, we can have the following types: Dr.Nazar Jawhar 1- Mild acute ( catarrhal) inflammation: ❖ Characteristic for mild infection of the mucous membrane (as viral upper respiratory tract infection). ❖ Hotness, redness and swelling. ❖ Complete resolution. 2- Serous inflammation: ❖ Excessive accumulation of protein-poor fluid resulting in blister formation. ❖ As in burn and viral infection of skin. Dr.Nazar Jawhar 3-Fibrinous inflammation: ❖ Characteristic of more severe injury (greater vascular permeability with exudation of large amount of fibrinogen. ❖ The outcome either: Complete resolution or organization (deposition of fibrin followed by ingrowth of new capillary & fibroblast ending in fibrosis. ❖ Common in inflammation of serosal membranes & joints. 4- Suppurative (purulent) inflammation: ❖ Characteristic by accumulation of large amount of pus with abscess formation. ❖ Certain bacterial infection. Dr.Nazar Jawhar  5-Acute ulceration: ❖ When infection is severe & affecting surface epithelium, it causes loss of part of the epithelium. 6- Pseudomembranous inflammation: ❖ Necrotizing infection of surface epithelium of the colon caused by certain bacteria (clostridium difficile). Dr.Nazar Jawhar Role of lymphatic in inflammation. Lymphatics also participate in the inflammatory response. As is well known, the small amount of interstitial fluid formed normally is removed by lymphatic drainage. In inflammation, lymph flow is increased and helps drain edema fluid from the extravascular space. In addition, leukocytes and cell debris may also find their way into lymph. In severe inflammatory reactions, especially to microbes, the lymphatics may transport the offending agent. The lymphatics may become secondarily inflamed (lymphangitis), as may the draining lymph nodes (lymphadenitis). Dr.Nazar Jawhar Inflamed lymph nodes are often enlarged, because of hyperplasia of the lymphoid follicles. This constellation of pathologic changes is termed reactive, or inflammatory, lymphadenitis. For clinicians, the presence of red streaks near a skin wound is a telltale sign of an infection in the wound. This streaking follows the course of the lymphatic channels and is diagnostic of lymphangitis; it may be accompanied by painful enlargement of the draining lymph nodes, indicating lymphadenitis. Dr.Nazar Jawhar  Definition: Inflammation of prolonged duration in which active inflammation, tissue destruction, and attempts at repair are proceeding simultaneously. Chronic inflammation results from: : : : Dr.Nazar Jawhar Chronic inflammation may arise in three ways: ❑: ❑: ❑: Dr.Nazar Jawhar  Components of chronic inflammation: In contrast to acute inflammation, chronic inflammation characterized by: ❖ Recruitment of mononuclear cells ( as….), (why?) ❖ Tissue destruction induced by persistent stimulus or by the inflammatory cells (HOW?). ❖ Attempts at healing by connective tissue replacement of damaged tissue, accompanied by proliferation of small blood vessels (angiogenesis) & fibrosis. Dr.Nazar Jawhar  Role of macrophages: ❑ Monocytes emigrate into the extravascular space ( by expression of specific adhesion molecules & secretion of specific chemotactic factors). ❑ Differentiate into larger macrophages: ❑ Then macrophages activated by cytokines (interferon), such activated macrophages secrete a variety of active products ( chemical mediators) which result in: - Tissue injury: as enzymes, O2 metabolites,.etc. - Fibrosis: as FGF,… Dr.Nazar Jawhar  GROSS MORPHOLOGICAL FEATURES OF CHRONIC INFLAMMATION: Gross features that are seen in chronic inflammation include: 1- : 2- : 3- : 4- : 5- : Dr.Nazar Jawhar  Definition: A distinctive pattern of chronic inflammatory reaction that characterized by formation of granuloma which is an aggregate of modified macrophages having a characteristic epithelial-like appearance (so called epithelioid histiocytes). Dr.Nazar Jawhar What is the importance of granulomatous inflammation? Granulomatous inflammation is important to be recognized because it is encountered in a few pathological conditions as: Infections: as Reaction to poorly digestible materials as inorganic metals, irritant lipids and some foreign materials Unknown immune disorder Dr.Nazar Jawhar as sarcoidosis. Granuloma: It is a focal area of granulomatous inflammation. It consists of a microscopic aggregation of epithelioid macrophages surrounded by a collar of lymphocytes & externally bounded by fibroblasts. Frequently several epithelioid macrophages fuse together to form a large multinucleated cells called giant cell. The central part of granuloma may exhibits necrosis. Dr.Nazar Jawhar  TYPES OF GRANULOMA: ❑ Foreign body granuloma: Formed in response to relatively inert foreign bodies that are poorly digestible & cannot be phagocytosed by a single macrophage so they fuse to form giant cell, as in suture material. ❑ Immune granuloma: Formed in response to the presence of insoluble particles that are capable of inducing a T-cell mediated immune response as in TB. MORPHOLOGY OF GRANULOMA: Dr.Nazar Jawhar  Systemic effects of inflammation Dr.Nazar Jawhar