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Inflammation 5
- 1.
- 2. Learning objectives • Summarizethe beneficial and harmful effects of inflammation • Define chronic inflammation and determine its causes • Identify the nature and origin of cells in acute and chronic inflammation • Determine cells of chronic inflammation • Describe components of chronic inflammation • Define granuloma • Explain pathogenesis of granuloma
- 3. Effects of acuteinflammation
- 4. Beneficial effects 1. Dilutionof toxins: by inflammatory exudate and allow them to be carried by lymphatics 2. Entry of antibodies: ↑ vascular permeability allow entrance of Abs to extracellular space Ab + Ag complement activation C5-9 C3b Neutralization of toxins
- 5. 3. Delivery ofnutrients and oxygen 4. Drug transport 5. Fibrin formation: Impede the movement of micro-organisms trap them then enhance phagocytosis 6. Stimulation of immune response Drainage of inflammatory exudate allow particulate and soluble Ags to reach LNs thus stimulate immune response 7. Prepares tissue for repair
- 6. Harmful effects ofinflammation 1. Digestion of normal tissues Collagenases and proteases may digest normal tissue leading to their destruction especially BV vascular damage e.g. glomerulonephritis 2. Swelling May be harmful specially in certain sites as Epiglottis airway obstruction especially in children death Cranial cavity ↑ intra-cranial pressure
- 7. 3. Inappropriate inflammatoryresponse Allergic inflammatory response may be life threatening as type I hypersensitivity reaction (anaphylactic shock) 4.Stasis and thrombosis may lead to extensive tissue damage 5. Pain may restrict joint movement leading to muscle atrophy
- 8. • 6. largeexudation e.g. in the pericarduim may disturb cardiac function • 7. release of lytic enzymes from dead cells may extend tissue damage
- 9. Chronic inflammation • Definition:an inflammation of prolonged duration in which Proceeding simultaneously
- 10. • 1. Chronicinflammation following acute inflammation • When the tissue destruction is extensive, or the bacteria survive and persist in small numbers at the site of acute inflammation • e.g. in osteomyelitis, pneumonia terminating in lung abscess. • 2. Recurrent attacks of acute inflammation • When repeated bouts of acute inflammation culminate in chronicity of the process e.g. in recurrent urinary tract infection leading to chronic pyelonephritis, repeated acute infection of gallbladder leading to chronic cholecystitis.
- 11. 3-De novo: Intracellularmicrobes which are of low toxicity but evoke immunological reaction; e.g. T.B bacilli and some viruses Immune reaction particularly auto-immune diseases Prolonged exposure to non-degradable but potentially toxic substances; e.g. silica, asbestos
- 12. GENERAL FEATURES OFCHRONIC INFLAMMATION • MONONUCLEAR CELL INFILTRATION Chronic inflammatory lesions are infiltrated by mononuclear inflammatory cells like phagocytes and lymphoid cells. • TISSUE DESTRUCTION OR NECROSIS Tissue destruction and necrosis are central features of most forms of chronic inflammatory lesions • PROLIFERATIVE CHANGES As a result of necrosis, proliferation of small blood vessels and fibroblasts is stimulated resulting in formation of inflammatory granulation tissue. Eventually, healing by fibrosis and collagen laying takes place.
- 15. SYSTEMIC EFFECTS OFCHRONIC INFLAMMATION • Fever Invariably there is mild fever, often with loss of weight and weakness. • Anaemia chronic inflammation is accompanied by anaemia of varying degree. • Leucocytosis As in acute inflammation, chronic inflammation also has leucocytosis but generally there is relative lymphocytosis in these cases. • ESR ESR is elevated in all cases of chronic inflammation. • Amyloidosis Long-term cases of chronic suppurative inflammation may develop secondary systemic (AA) amyloidosis
- 16. TYPES OF CHRONIC INFLAMMATION •Chronic non-specific inflammation When the irritant substance produces a non-specific chronic inflammatory reaction with formation of granulation tissue and healing by fibrosis, it is called chronic non-specific inflammation e.g. chronic osteomyelitis • Chronic granulomatous inflammation In this, the injurious agent causes a characteristic histologic tissue response by formation of granulomas e.g. tuberculosis, leprosy, syphilis, actinomycosis, sarcoidosis
- 17. Granulomatous inflammation • Granulomais defined as a circumscribed, tiny lesion, about 1 mm in diameter, composed predominantly of collection of modified macrophages called epithelioid cells, and rimmed at the periphery by lymphoid cells. The word ‘granuloma’ is derived from granule meaning circumscribed granule-like lesion, and -oma which is a suffix commonly used for true tumours but here it indicates a localised inflammatory mass or collection of macrophages.
- 19. Pathogenesis of agranuloma • Formation of a granuloma involves engulfment of the invading agent by the macrophages, failure to degrade the antigen, morphologic change of macrophages to epithelioid cells, and incoming CD4+ T cells which elaborate various cytokines which contribute to proliferation and activation of cells.
- 21. Components of agranuloma
- 23. Differences between acuteand chronic inflammation ChronicAcute Long (weeks – months) Short (days)1. Duration insidiousacute2. Onset specificNon-specific3. Specificity Lymphocytes, macrophages, plasma cells and fibroblasts Neutrophils macrophages 4. Cells
- 24. ChronicAcute angiogenesisVasodilatation, ↑ vascular permeability 5. Vascular changes --+++6.Exudation and edema --+++7. Cardinal signs Usually +veUsually -ve except in suppurative inflammation 8. Tissue necrosis
- 25. ChronicAcute +veUsually -ve9. Fibrosis Low-grade fever Weightloss anemia High fever10. Systemic manifestations Frequently none Variable leukocyte changes ↑ neutrophils Lymphocytosis in viral infection 11. Changes in peripheral blood