INFLAMMATION

 INFLAMMATION

Brief understanding of the common terms used in pathology:-

Inflammation:-

     Inflammation is defined as the local response of a living mammalian vascular tissue to injury due to any agent. It is a body defense reaction in order to eliminate or limit the spread of injurious agent, followed by removal of the necroced cell or tissue.

     The agents causing inflammation may be as under-

1. Inffective agents-  Bacteria, virus and their toxins, fungi, parasites.

2. Immunological agents-  cell mediated and antigen-antibody reaction.

3. Physiological agents-  heat, cold, radiation, mechanical trauma

4. Chemical agents- organic and inorganic poison

5. Inert material-  Foreign body

Sign of inflammation:-

                                       Celsius has given four sign of inflammation-

1. Rubor- redness

2. Tumor - swelling

3. Calor- heat

4. Dolor- pain

given by verchow-

5. Funtio loesa- loss of function

Type of inflammation:-

                                       Depending upon the defense capacity of the host and duration of response, inflammation can be classified as acute and chronic.

1. Acute inflammation:-

          Acute inflammation is of short duration (lasting less than 2 weeks) and represents the early body reaction, resolves quickly and is usually followed by healing.

2. Chronic inflammation:-

             Chronic inflammation is of longer duration and occur either after the causative agent of acute inflammation persist for a long time or the stimulus is such that it induces chronic inflammation from the begining.

Morphology of Acute inflammation:-

Inflammation of an organ is usually named by adding the suffix "Itis".

ex: Meningitis, hepatitis, cholecystitis, phlebitis etc.

  A few morphological varieties of acute inflammation are-

1.Pseudo membranous inflammation:-

       It is a inflammatory response of mucus membrane to toxins of diphtheria or irritant gases. As a result of epithelium plasma exudes on the surface where it coagulates and together with necrosed epithelium forms false membrane.

2. Ulcer:-

Ulcer are local defect on the surface of an organ produced by inflammation. Common site for ulceration are the stomach, duodenum, intestine, etc.

In acute stage there is infiltration of polymorph with vasodialation. while long standing ulcer developed infiltration by lymphocytes, plasmacells and macrophages with associated fibroblastic prolifiration and scarring.

3. Suppuration:-

   When acute bacterial infection is accompanied by intense neutrophilic infiltration in the inflammed tissue. It result in tissue necrosis. A cavity is formed which is called an abscess and contain purulent exudate or pus and the process formation is called suppuration. The bacteria formation is called suppuration. The bacteria which cause suppuration is called pyogenic bacteria. 

4. Cellulitis:-

      It is a defuse inflammation of soft tissue resulting from spreading effect of substance like Hyaluronidase enzyme by some bacteria.

5. Bacterial infection of the blood:-

      This include following three condition-

a. Bacteremia:-

   It is defined as a presence of small numbers of bacteria in the blood which do not multiply significantly. Ex- Salmonella typhi, escherichia etc.

b. Septicemia:-

   It means presence of rapidly multiplying, highly pathogenic bacteria in the blood. It is generally accompanied by systemic effect.

c. Pyramia:-

  It is the dissemination of small septic thrombi in the blood which cause their effect at the site where they are lodged.

Systemic effect of Acute inflammation:-

  Acute inflammation is associated with systemic effects as -

1. Fever

2. Leucocytosis

3. Lymphangitis

4. Shock

1. Fever:-

     Fever occurs due to Bacteraemia.

2. Leucocytosis:-

     It is commonly accompanies the acute inflammatory reaction usually in the range of 15000-20000 per cubic mm.

3. Lymphangitis:-

  It is one of the important manifestation of localize inflammatory injury. The lymphatics and lymphnodes that drain the inflammed tissue show reactive inflammatory changes in the form of lymphangitis and lymphadenitis.

4. Shock:-

  Shock may occur in severe cases. Shock is the clinical syndrome of cardiovascular collapse.

Fate of Acute inflammation:-

   The acute inflammatory process can in one of the following outcomes-

1.Resolution:-

   It means complete return to normal tissue following acute inflammation. It occurs when tissue changes are slight and the cellular changes are reversible.

2. Healing:-

   Healing by fibrosis take place when the tissue distraction in acute is inflammation is extensive so that there is no tissue regeneration. But when tissue loss in superficial, it is restored by regeneration.

3. Suppuration:-

    When the pyogenic bacteria causing acute inflammation results in severe tissue necrosis, The process progress of suppuration, the abscess may drained, if not may get organised by dense fibrous tissue, and in time get calcified.

4. Chronic Inflammation:-

   Persisting or recurrent acute inflammation may progress to chronic inflammation in which the process of inflammation and healing proceed by site.

CHRONIC INFLAMMATION:-

  Chronic inflammation is defined as prolonged process in which tissue distraction and inflammation occur at the same stage.

  Chronic inflammation can be caused by one of the following three ways-

1. Chronic inflammation following acute inflammation:-

     When the tissue distraction is extensive or the bacteria servive and persist in small number at the site of acute inflammation. Ex- osteomollitis

2. Recurrent attack of acute inflammation:-

     When repeated attack of acute inflammation occur in chronicity of the process. Ex:- recurrent UTI

3. Chronic inflammation starting de novu:-

    When the infection with organism of low pathogenicity is chronic from the begining. ex:- TB

General features of chronic inflammation:-

   Following general features characterize any chronic inflammation-

1. Mono nuclear cell infiltration:-

    Chronic inflammatory lesions are infiltrated by mono nuclear inflammatory cell. like phagocytes and lymphoid cell.

   Phagocytes are represented by circulating monocytes, tissue macrophages, epithiloid cells and some times multinucleated giant cell. The macrophages comprises the most important cell in chronic inflammation. 

2. Tissue distruction or necrosis:-

   Tissue distruction and necrosis are central feature of most form of chronic inflammatory lesions. This is brought by activated macrophages, which release a variety of biological active substance like protiase, elastiase, lipase.

3. Proliferated changes:-

      As a result of necrosis, proliferation of small blood cells and fibroblast stimulated resulting in formation of inflammatory granulation tissue.

Systemic effect of chronic inflammation:-

 Chronic inflammation is associated with following systemic feature-

1. Fever-

               There is a mild fever, often with loss of weight and weakness.

2. Anemia-

                 Chronic inflammation is accompanied by anemia of varrying degree.

3. Leucocytosis-

                    As in acute inflammation, chronic inflammation also has leucoctosis but generally there is lymphocytosis.

4. ESR-

            ESR is elevated all cases of chronic inflammation.

5. Amylotosis-

                Long term cases of chronic suppurative inflammation may developed systemic amylotosis.

Types of chronic inflammation:-

     Chronic inflammation is subdivided into two type-

1. Chronic non-specific inflammation:-

       It is characterized by non-specific inflammatory cell infiltration. ex- chronic osteomollitis, lung abscess.

2. Chronic granulomatous inflammation:-

        It is characterized by formation of granuloma. Ex- TB, leprosy, sarcoidis etc.

Note:-

     Granuloma is defined as circumscribed, tiny lesion about 1mm of diameter, composed predominatly of collection of modified macrophages called epitheloid cells and rimmed at the periphery by lymphoid cell.