Scientists say: Inflammation

When your body is injured, it knows how to respond — with heat and attack cells

bug bite

Ouch! The mosquito bite on this girl’s arm is big and swollen because of inflammation.


Inflammation /in-flah-MAY-shun/ noun.

One way that the body responds when its cells get injured. Hurt cells send out distress signals. Cells from the immune system then flock to the site. The area also gets more blood delivered to it. In some cases, these responses can cause swelling, redness and pain or itching. In fact, that’s what happens with a mosquito bite. But inflammation can occur anywhere in the body, from the brain and gut to the joints and lungs.

In a sentence

Tiny particles pollute the air in many large cities. When we breathe in these particles, they can cause inflammation in our lungs, and even in our brains.

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Power Words

immune system  The collection of cells and their responses that help the body fight off infection.

inflammation    The body’s response to cellular injury; often involves swelling, redness, heat and pain.

pollutant  A substance that taints something — such as the air, water, our bodies or products. Some pollutants are chemicals, such as pesticides. Others may be radiation, including excess heat or light. Even weeds and other invasive species can be considered a type of biological pollution.

Bethany Brookshire was a longtime staff writer at Science News Explores and is the author of the book Pests: How Humans Create Animal Villains. She has a Ph.D. in physiology and pharmacology and likes to write about neuroscience, biology, climate and more. She thinks Porgs are an invasive species.

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