Inflammation

Last revised by Yaïr Glick on 16 Nov 2022

Inflammation is a response to a noxious stimuli which can be either be acute or chronic.

The cardinal signs of inflammation include:

  • heat (calor)

  • redness (rubor)

  • swelling (tumor)

  • pain (dolor)

  • loss of tissue function (functio laesa)

Subtypes

Acute Inflammation

Acute inflammation occurs within the first few hours after an injury.

In acute inflammation there are vascular and exudative phases.

  • vascular: dilatation and increased permeability

  • exudative: fluid and cells escape from permeable venules

The outcome of acute inflammation can be:

  • resolution (restoration of normal function)

  • non resolution

  • abscess

  • organization (scarring)

  • progression to chronic inflammation

Chronic Inflammation

Chronic inflammation occurs when there is a persistent damaging stimulus. This eventually heals by either scarring or granuloma formation.

Chronic inflammation differs from acute inflammation as it can last for a much longer period of time i.e. from months to years.

Chronic inflammation is characterized by infiltration with mononuclear cells (macrophages, lymphocytes).

Outcomes of chronic inflammation include:

  • a continuing response to persisting inflammatory triggers, such as infectious agents, autoimmune products, and immune complexes.

  • the inflammatory cells including lymphocytes and macrophages will either be cleared or remain at the site.

  • the development of giant cells along with fibrosis and/or necrosis.

Granulomatous Inflammation

Granulomatous inflammation is specific subtype of chronic inflammation characterized by aggregation of epitheliod histiocytes. Examples of Type IV hypersensitivity reaction include:

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