Category:Acute Inflammation

Fluids

Serous Inflammation

Catarrhal

• Catarrhal inflammation is a mild form of inflammation.
• Occurs on mucous membranes where there are many mucus cells.
• The consistency of catarrhal exudate varies from water to gelatinous.
• Colour varies from cloudy to pinkish.
• This form of exudation is essentially a shedding of epithelium containing many mucus cells, neutrophils, some RBCs, and flecks of fibrin.

• Common in mild forms of rhinitis, tracheitis, bronchitis, gastritis and enteritis.

Fibrinous

• Fibrinous exudation occurs in more severe endothelial injury.
  • Injury results in the escape of fibrinogen, which is converted to fibrin.
• The fibrin formed appears as a yellowish coagulation on the surface of or within a tissue.
  • Common in the lungs and on serous surfaces.
• In hollow organs the fluid may coagulate to form casts of the lumen.

• Fibrin will peel off from the underlying tissue without causing damage to it.

Diptheritic

• Diphtheritic exudate a more severe form of fibrinous exudate in which there is considerable necrosis of the underlying tissues.
• Diptheritic exudate is firmly adherent to the underlying tissue.
  • Attempts at removal cause tearing of this tissue>
• Commonly seen with internal surface fungal infections.
  • E.g. in the nose of the dog and the guttural pouch of the horse.
  • Fungal toxins penetrate the underlying tissue causing coagulation necrosis.

Haemorrhagic

• This is a severe acute to peracute inflammation in which haemorrhage is the main component.

• Seen in the lymph nodes, lungs and intestine in severe inflammation.

Purulent

• In purulent inflammation, pus is the predominant feature.
  • Pus is an admixture of dead and dying neutrophils with necrotic cells and a pyogenic agent.
    • Proteolytic enzymes released by the dying neutrophils lyse tissue cells to produce a fluid.
• Colour varies depending upon the agent.
  • May be white, yellow, green or brown.
• An abscess is a circumscribed sphere of pus surrounded by a pyogenic membrane.
  • The pyogenic membrane is composed of capillaries bringing neutrophils into the sphere.
  • This rapidly becomes enveloped by a fibrous tissue capsule.
    • A local connective tissue response attempting to wall off the purulent irritant from nearby normal tissue.