Friday, March 20, 2015

Acute inflammation

Posted by Radiology Madeeasy

Acute inflammation
A 28 year old man develops an acute paronychia and subsequent spreading sepsis. The tissue exudate has a higher protein content than normal tissue because?

  

A.

Breakdown of tissue cells release protein

 

 

B.

Capillary walls are more permeable

  

C.

Increased blood flow transports more protein into the area

  

D.

Intracapillary pressure is raised

  

E.

Plasma cells release gamma globulin

 

The increased permeability allows the exudation of plasma proteins.

 

Acute inflammation

Inflammation is the reaction of the tissue elements to injury. Vascular changes occur, resulting in the generation of a protein rich exudate. So long as the injury does not totally destroy the existing tissue architecture, the episode may resolve with restoration of original tissue architecture.

Vascular changes

  • Vasodilation occurs and persists throughout the inflammatory phase.
  • Inflammatory cells exit the circulation at the site of injury.
  • The equilibrium that balances Starlings forces within capillary beds is disrupted and a protein rich exudate will form as the vessel walls also become more permeable to proteins.
  • The high fibrinogen content of the fluid may form a fibrin clot. This has several important immunomodulatory functions.

Sequelae

Resolution

  • Typically occurs with minimal initial injury
  • Stimulus removed and normal tissue architecture results

Organisation

  • Delayed removed of exudate
  • Tissues undergo organisation and usually fibrosis

Suppuration

  • Typically formation of an abscess or an empyema
  • Sequestration of large quantities of dead neutrophils

Progression to chronic inflammation

  • Coupled inflammatory and reparative activities
  • Usually occurs when initial infection or suppuration has been inadequately managed

Causes

  • Microbacterial infections e.g. Viruses, exotoxins or endotoxins released by bacteria
  • Chemical agents
  • Physical agents e.g. Trauma
  • Hypersensitivity reactions
  • Tissue necrosis

Presence of neutrophil polymorphs is a histological diagnostic feature of acute inflammation