WHAT IS INFLAMMATION ?

 INFLAMMATION😖

INTRODUCTION

DEFINITION AND CAUSES. 

Inflammation is defined asthe local response of living mammalian tissues to injury dueto any agent. It is a body defense reaction in order to eliminateor limit the spread of injurious agent, followed by removal of the necrosed cells and tissues.

The agents causing inflammation may be as under:

1. Infective agents like bacteria, viruses and their toxins,

fungi, parasites.

2. Immunological agents like cell-mediated and antigenantibody

reactions.

3. Physical agents like heat, cold, radiation, mechanical

trauma.

4. Chemical agents like organic and inorganic poisons.

5. Inert materials such as foreign bodies.

Thus, inflammation is distinct from infection—while

inflammation is a protective response by the body to variety

of etiologic agents (infectious or non-infectious), while

infection is invasion into the body by harmful microbes and

their resultant ill-effects by toxins. Inflammation involves 2

basic processes with some overlapping, viz. early inflammatory

response and later followed by healing. Though both

these processes generally have protective role against

injurious agents, inflammation and healing may cause

considerable harm to the body as well e.g. anaphylaxis to

bites by insects or reptiles, drugs, toxins, atherosclerosis,

chronic rheumatoid arthritis, fibrous bands and adhesions

in intestinal obstruction.

As discussed earlier (Chapter 4), “immunity or immune

reaction” and “inflammatory response” by the host are both

protective mechanisms in the body—inflammation is the

visible response to an immune reaction, and activation of

immune response is almost essential before inflammatory

response appears.

SIGNS OF INFLAMMATION. The Roman writer Celsus

in 1st century A.D. named the famous 4 cardinal signs of

inflammation as:

rubor (redness);

tumor (swelling);

calor (heat); and

dolor (pain).

To these, fifth sign functio laesa (loss of function) was later added by Virchow. The word inflammation means burning. This nomenclature had its origin in old times butnow we know that burning is only one of the signs of inflammation.

TYPES OF INFLAMMATION.

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

A. Acute inflammation is of short duration (lasting less than2 weeks) and represents the early body reaction, resolves quickly and is usually followed by healing.

The main features of acute inflammation are:

1. accumulation of fluid and plasma at the affected site;

2. intravascular activation of platelets; and

3. polymorphonuclear neutrophils as inflammatory cells.

Sometimes, the acute inflammatory response may be

quite severe and is termed as fulminant acute inflammation.

B. Chronic inflammation is of longer duration and occurseither after the causative agent of acute inflammation persistsfor a long time, or the stimulus is such that it induces chronicinflammation from the beginning. A variant, chronic activeinflammation, is the type of chronic inflammation in whichduring the course of disease there are acute exacerbations of activity.

The characteristic feature of chronic inflammation is

presence of chronic inflammatory cells such as lymphocytes,

plasma cells and macrophages, granulation tissue formation,

and in specific situations as granulomatous inflammation.

In some instances, the term subacute inflammation is used

for the state of inflammation between acute and chronic.