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L35 - Pathology and Healing Inflammation Define acute, chronic and…

- - - - Regeneration
        Tissue is able to regrow to replace damaged areas
        E.g. Skin, liver, nerves, bone
      - Repair by scar formation
        Tissue cannot replace damage functionally, so uses connective tissue instead
        
        Scar matures over time
        
        Abnormal scarring; Keloid, Contracture
      - Resolution
        Tissue is able to return to pre-injury state
    - - Cutaneous Tissue
        
        Healing by First Intention
        Deep and narrow injury, rejoin sides then heal from bottom up, fibrous union, largely regenerated tissue
        
        Healing By Second Intention
        Wound is too wide, heals from the bottom up. Extensive angiogenesis. Scar left, with cavity
      - Osseous tissue
        
        Hameatoma formation
        
        Fibrocartillagenous callus formation
        
        Bony Callus formation
        
        Bone remodelling
      - Nervous-Tissue
        
        The myelin will withdraw to nearest node, all of the myelin distal to node will degenerate.
        
        Regenerate by elongating towards the tissue
    - - Local Factors
        
        Infection
        
        Extent of Injury
        
        Mechanical Injury
        
        Foreign material
        
        Poor Perfusion
      - Systemic Factors
        
        Sepsis
        
        Diabetes
        
        Nutritional Deficiency
        
        Glucocorticoids (steroids)
        
        Hypoxia
- - - - Activation
        Activation of leukocytes and proteins destroy and eliminate offending substance
        
        Regulation
        Reaction is controlled and terminated
        
        Repairation
        Tissue damage is repaired
  - - - Acute Phase Response (increase in proteins
      - Leukocytosis
      - Fever => Sepsis
      - Shivering, chills, anorexia, somnolence (sleepiness), malaise
    - - Purulent (Pus forming)
      - Absceses (collection of puss in tissue)
        Empyema = colletion of puss in anatomical space (pleura)
      - Serous= protein rich exudate at serous surfaces (peritonitis)
      - Fibrinous = similar to serous, however there is marked leakage
      - Ulcerative = inflammation associated with erosion of mucosal surfaces
- - - - Activation
        Ligands binding to EC domain of receptors, inducing conformational change and activating IC signal transduction
        
        Elimination
        Typically mediated through phagocytosis
        (offending agent removed)
        
        Chronic Inflammation
        Response of prolonged duration (Weeks=>months) where inflamm, repair and injury occurring simultaneously
        
        Causes
        
        Persistent Infection
        
        microbes which are difficult to expel (mycobacteria, funghi etc)
        
        Hypersensitivity
        
        Prolonged exposure to toxic agaent (endo/exo)
        
        Cell mediated Response (mononuclear/lymphocytic mediators over neutrophils)
        
        Attempts at Angiogenesis to heal
        
        Granulomatous Formation
        
        Induced by T-cell and macrophage when offending agent is too big/cannot be eradicated
        
        Characterised by clusters of histocytes (tissue macros) => giant cells (syncitium of multi-nucleated macrophages)
        
        Necrotising (infect.) or non-necrotising (non-inf.)
        
        Examples
        
        Silica/coal dust
        
        Mycobacterial
        
        Idiopathic (Crohn's disease)