Inflammatory response: A fundamental type of response by the body to disease and injury, a response characterized by the classical signs of "dolor, calor, rubor, and tumor" -- pain, heat (localized warmth), redness, and swelling.

Innumerable insults (a mosquito bite, a splinter, a virus infection, a bruise, a broken bone) can trigger an inflammatory response and dispatch cells and chemicals to the site to repair the damage. Inflammation is a key part of the body's defense system, an indispensable protective response by the body's system of self-defense.

Acute inflammation is short-lived, lasting only a few days. If it lasts longer, it is referred to as chronic inflammation. Chronic inflammation may last weeks, months, or beyond.

Paradoxically, the inflammatory process itself may cause tissue damage while it is engaged in healing and repair. Thus, inflammation may play a role in such diverse disorders as Alzheimer disease, meningitis, atherosclerosis, cystic fibrosis, asthma, cirrhosis of the liver, inflammatory bowel disease (IBD), diabetes, osteoporosis, and psoriasis.

For more information, see: Inflammation.