8 - Inflammation (outcomes) Flashcards
Suppuration
The formation of pus, referred to as suppurative or purulent
Pus
An exudate containing dead and living neutrophils, dead and living bacteria, protein, cell fragments etc
Abcess
Pus filled cavity
Empyema
An accumulation of pus in a naturally occurring body cavity
Evolution of an abscess
- Starts as acute inflammatory exudate with many neutrophils
- Proteins, bacteria and polymorphs aggregate to form a mass
- Tissue death (necrosis) ensures
- Process of organisation
- Fibroblasts start to lay down scar tissue (collagen)
- Pus resorbed (if small amount) or can burst onto (‘point’) to external surface (sinus) or adjacent body cavity (fistula) and be
discharged in this way or enter bloodstream to result in septicaemia - Collagen deposition proceeds to formation of mature scar
Granulation tissue (process referred to as organisation)
New capillaries and fibroblasts develop at edge of accumulated
material
Examples of acute inflammatory reaction in the lung caused by pyogenic bacteria
Bacterial Pneumonia (Lobar pneumonia and Bronchopneumonia)
Cause of lobar pneumonia
Streptococcus Pneumoniae
Lobar pneumonia
- Alveolar spaced filled with exudate (meutrophils, fibrin, dead bacteria)
- Referred to as ‘consolidation’ or ‘hepatisation’
- Consolidation of entire lobe
Outcomes of pneumonia
- Resolution
- Abscess formation
- Empyema
- Fibrosis and scarring
- Septicaemia
- Death
Bronchopneumonia
Patchy distribution of consolidation, related to bronchi
Chronic inflammation
- Inflammation enduring longer than acute
- May be primary (e.g. TB) but often results from acute inflammation when causative agent cannot be removed
- Neutrophils largely replaced by lymphocytes, plasma cells (and macrophages)
- Macrophages often fuse to form giant cells
- Organisation
- Fibrosis/scarring common
Chronic peptic ulcer
- Chronic ulcer occurring in an area of acid pepsin digestion (stomach, duodenum, oesophagus)
- Associated with H. pylori infection
Acute gastritis ulceration
related to use of non steroidal anti-inflammatory drugs eg aspirin, ibubrufen, naproxen, alcohol, stress
Outcomes of chronic peptic ulcer
- Resolution (rare without appropriate therapy)
- Haemorrhage
- Fibrosis (± stenosis)
- Perforation
- Penetration (± fistula formation)
- Malignant transformation (very rare)
Example of chronic inflammatory disease
Tuberculosis (Mycobacterium tuberculosis)
Primary TB
Immune system is unable to defend against the infection. Can effect any organ
Secondary TB
Reactivation of latent tuberculosis infection
Resolution
- Removal of exudate
- Regeneration of tissue if possible
- Complete return to normal
Repair
- Occurs when resolution
impossible (severe, ongoing damage, or tissue cannot regenerate) - Involves formation of
granulation tissue
(organisation) - Maturation of granulation
tissue to scar tissue (fibrosis)
When does organisation often occur
When exudation or damage is excessive and cannot be removed
Healing by primary intention
- Occurs in clean incised
wounds with apposed
edges (eg surgical wounds) - Results in minimal scarring
- Occurs in shorter time
- Strengthening, devascularisation continues longer
Healing by secondary intention
- Occurs in open wounds
(loss of tissue, necrosis or infection) - Often results in
significant scarring (fibrosis) - Process may continue for months or years
Fibrosis
End result of organisation in wound healing and chronic inflammation
Process of fibrosis
- Fibrocytes stimulated by polypeptides from surrounding damaged cells
- Become active fibroblasts. Commence protein synthesis
- Secretion of ground substance including fibrinonectins
- Secretion of procollagen
- Condensation to fine reticulin fibres
- Further condensation to mature collagen fibres
- Binding and weaving to form scar tissue
- Fibroblasts revert to fibrocytes
Local factors affecting wound healing
- Poor blood supply
- Infection
- Excessive movement or irritation
- Foreign material
General factors affecting wound healing
- Deficiency of Vitamin C (scurvy), essential amino acids, zinc
- Excess adrenal corticosteroids
- Intercurrent debilitating chronic disease
