Inflammation Flashcards
Define acute inflammation.
Response of vascularized tissue that brings immune cells to sites where they are needed to eliminate offending agents
What are the 5 Cardinal signs of inflammation?
Redness, Warmth, Swelling, Pain, Loss of Function
What are the special scenarios of acute inflammation?
• Serous inflammation in blisters
• Fibrinous inflammation in pericarditis, peritonitis, pleuritis
• Suppurative inflammation in abcesses of localized tissue
• Ulcerative inflammation in epithelial surfaces with defects
Define chronic inflammation.
Prolonged duration in which inflammation, tissue injury and attempts at repair coexist in varying degrees
Define granulomatous inflammation.
Aggregates of epithelioid histiocytes
Describe granulomatous inflammation in terms of histological appearance.
• multinucleated giant cells
• surrounded by lymphocytes
• caseous necrosis or no necrosis in the centre
• can be caused by TB infection
Define organisation.
Conversion of inflammatory exudate to fibrous scar
Define healing.
Repair process consisting of regeneration and organisation.
Describe the three results of healing and repair.
- Resolution: complete disappearance of inflammatory exudate
- Fibrosis: excessive fibrous tissue accumulation
- Granulomatous inflammation: aggregates of epithelioid histiocytes
What are the 5 processes involved in healing?
- Regeneration
- Cell migration
- Angiogenesis
- Clearing of cell debris/infectious stimuli by macrophages
- ECM synthesis and remodelling
Describe the 2 types of healing.
- Primary intention: wound has closely apposed edges, minimal hematoma, requires little organisation –> minimal scar
- Secondary intention: wound edges are far apart (eg laceration), requires a lot of organisation + large amount of granulation tissue –> extensive scar formation
Highlight the role of macrophages in repair and healing.
M2 alternative macrophages are anti-inflammatory for healing and repair.
• clear cellular debris from inflammation site
• secrete cytokines for ECM synthesis (containing collagen, proteoglycans, hyaluronic acid)
if macrophages are depleted or dysfunctional, wound healing is delayed.
Describe the features of the Regeneration arm of Healing.
• replacing lost cells to ensure no loss in function
• tissue must contain pluripotent stem cells capable of dividing
• labile tissues are best at regenerating, followed by stable quiescent tissues. permanent tissues lack regenerative capacity
• more specialised cells are more difficult to regenerate
• ECM must be intact for regeneration to take place
Describe the processes of the Repair arm of Healing.
• loss in function due to fibrous tissue repair
• involves granulation tissue formed by angiogenesis and fibroblast proliferation
• involves wound contraction by myofibroblasts
• involves type III collagen synthesis and maturation by fibroblasts (requires vit C, zinc, amino acids)
• type III collagen is replaced by type I collagen later
• involves collagen remodeling to form a scar
Describe the appearance of the site of Healing and Repair.
• initial wound is red due to angiogenesis
• healing stage of wound is white due to collagen deposition and fibrous tissue
• healthy granulation tissue is pinkish
