Inflammation is the body's first response to injury or infection. It brings blood, fluid and white cells to the area to remove the cause and clear the way for repair.
The classic signs
Redness, heat, swelling, pain and loss of function. They come from wider blood vessels, leaky capillaries and chemicals such as histamine and prostaglandins.
Vessels and fluid
Small vessels widen, so more blood reaches the area. Capillaries leak fluid and proteins, which causes swelling and lets defense cells reach the tissue.
White cells
Neutrophils arrive first, within hours, and kill microbes. Macrophages follow over the next days to clear debris and release signals that start repair.
Regrow or scar
Tissues whose cells divide well, like skin and liver, can regenerate. Tissues that cannot, like heart muscle, are replaced by scar made of collagen, which holds but does not work like the original.
Acute and chronic
Acute inflammation lasts days and settles. Chronic inflammation lasts weeks or longer and slowly damages tissue, as in rheumatoid arthritis or a nonhealing wound.
At the bedside
Check wounds and IV sites for the classic signs, and note spreading redness, pus or fever, which suggest infection. Blood tests such as CRP and the white cell count help track inflammation over time.
Related guides
Written by Making Synapses. Topic reference: OpenStax, Anatomy and Physiology 2e (no text adapted).