Scientists Say: Plasma

This term can refer to a state of matter or a component of blood

Plasma is the most common state of matter in the universe. It exists in all the stars in the night sky.

Hubble Heritage Team, D. Gouliermis (MPI Heidelberg) et al, (STScI/AURA), ESA, NASA

Plasma (noun, “PLAZ-muh”)

The word plasma can mean two very different things. In physics, plasma refers to one of the four states of matter, along with solid, liquid and gas. Plasma is gas that has an electric charge.

Plasmas form when extra energy — such as heat — is added to a gas. This extra energy can knock electrons off the atoms or molecules in the gas. What’s left is a mix of negatively charged electrons and positive ions. That mix is plasma.

Because plasmas are made of charged particles, they can do things that ordinary gases cannot. For instance, plasma can conduct electricity. Plasmas also can respond to magnetic fields. Plasma might sound exotic, but it’s the most common state of matter in the universe. Stars and lightning bolts contain plasma. Human-made plasmas glow in fluorescent lamps and neon signs.

In medicine, the word plasma refers to the liquid part of blood. This yellowish fluid makes up about 55 percent of our blood. The rest is red blood cells, white blood cells and platelets. Plasma is about 90 percent water and seven percent proteins. The fluid also contains vitamins, hormones and other ingredients.

Blood plasma has a lot of important jobs. It delivers nutrients to cells and carries away cellular waste. Plasma also shuttles proteins for blood clotting to injuries, helping the body heal. And it carries antibodies that help fight off infection. Donated blood plasma can be used to treat burns and other injuries. It’s also used to treat patients with immune diseases, bleeding disorders and other chronic illnesses.

In a sentence

The solar wind is a stream of plasma that flows off the sun.

Plasma collected at blood donation centers is used to treat burns, chronic illnesses and other diseases.

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Maria Temming is the assistant editor at Science News for Students. She has bachelor's degrees in physics and English, and a master's in science writing.

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