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.