An Overview of Inflammation

Inflammation is the reaction of tissues to injury and is designed to eLiminate the cause of damage and pave the way for heaLing. A particularly important purpose of an inflammatory response is to provide a first Line of defense against infection. The cLinical signs of acute inflammation (redness, swelLing, heat, and pain) have been recognized since antiquity. Three major physiological changes occur in inflamed tissues. Dilation of blood vessels increases the flow of blood to the area of damage, whereas increased permeabiLity of the vessel wall allows plasma constituents to enter the surrounding injured tissue. Circulating white blood cells also emigrate from the blood to the tissues, where they clear microbes and debris and initiate reactions of the immune response. Collectively, these changes deLiver to a damaged tissue the components that are needed to deal with the insult. A compLicated network of cells and chemical mediators must cooperate first to ignite the reactions of inflammation and then to dampen them when the crisis has been resolved. Inflammation is intended to benefit the body, and most often, it fulfills this goal. However, an inflammatory response can go awry, resulting in collateral damage to healthy tissues and exacerbation of disease.