Inflammation
Inflammation is the body's reaction to injury. When tissue is injured, there are a series of changes that occur--we call these changes inflammation. An injured and inflamed area of the body undergoes continuous change as the body heals and repairs itself.
When an injury occurs, the body responds with the four hallmarks of inflammation: pain (dolor), heat (calor), redness (rubor), and swelling (tumor). Think of a bee sting. First there is pain from the sting--the initial injury. The body's response to the injury produces redness, heat and swelling, plus some additional pain. This occurs because the blood vessels in the area of the injury dilate; this occurs within 30 minutes of the injury. White blood cells then migrate to the area. If the injury is not too severe, the blood vessels will return to normal in six to eight hours and repair can begin.

