Chronic Inflammation Flashcards
Cells involved
Lymphoctes
Plasma cells
Macrophages
Fibroblasts
Major causes
- Autoimmune disease
- Materials resistant to digestion: mycobacteria, brucella, viruses
- Exogenous substances; sutures, joint replacements…
- Endogenous substances; necrotic tissue, keratin, hair
- Follows acute inflammation
- Persistent injury or infection
- Prolonged exposure to a toxic agent.
Effects
Often no specific sore bit, malaise, weight loss, loss of function.
Outcome
Organisation; granulation tissue results in healing and repair leading to fibrosis ad scarring.
Adverse effects of tissue scarring
Reduced function/movement, weakening of muscles/tendons, chronic pain, unsightly, emotional effects, hardness
Mechanism of scar formation
- Growth of capillaries into inflammatory mass
- Access of plasma proteins and macrophages
- Fibroblasts lay down collagen to repair damaged tissue
- Collagen replaces exudate
- Patches defects and replaces dead/necrotic tissue
- Contracts and pulls together.
Sequence of events for healing and repair
- Injury
- Blood clots
- Granulation tissue growth with angiogenesis
- Phagocytosis of fibrin
- Myofibroblasts move in and lay down collagen
- Contraction of scar
- Re-epithelialisation.
In fracture repair granulation tissue contains osteoblasts as well as fibroblasts.
Factors favouring wound healing
Cleanliness, apposition of edges, sound nutrition, metabolic stability and normality, normal inflammatory and coagulation mechanisms, local mediators.
Role of angiogenesis in healing and repair
The formation of new blood vessels stimulated by Vascular Endothelial Growth Factor (VEGF) released by hypoxic cells enables blood supply to enter damaged tissue.
Factors that impair healing and repair
Dirty, gaping wound, large haematoma, poorly nourishes, lack of vitamins C and A, abnormal carbohydrate metabolism, diabetes, corticosteroid therapy, inhibition of angiogenesis.
