Glossary of Medical Terms

A chemical substance found naturally in small amounts in plants, trees, volcanoes, and forest fires. Acetone is also made by the body when fats are broken down. It is also found in tobacco smoke, car exhaust, and trash landfills. In industry, acetone is used in some plastics, fibers, medicines, household cleaners, glues, and nail polish removers. Being exposed to high levels of acetone may irritate the skin, eyes, nose, throat, and lungs. It can cause headaches, nausea, vomiting, dizziness, confusion, loss of consciousness, and other health problems.

A small molecule made of two carbon, three hydrogen, and one oxygen atoms. Acetyl groups are added to or removed from other molecules and may affect how the molecules act in the body.

A form of the natural substance carnitine that is being studied as a way to prevent tissue damage caused by chemotherapy. Carnitine is made in muscle and liver tissue and is found in certain foods, such as meat, poultry, fish, and some dairy products. It is used by many cells in the body to make energy from fat. Also called acetyl-L-carnitine hydrochloride and ALCAR.

A form of the natural substance carnitine that is being studied as a way to prevent tissue damage caused by chemotherapy. Carnitine is made in muscle and liver tissue and is found in certain foods, such as meat, poultry, fish, and some dairy products. It is used by many cells in the body to make energy from fat. Also called acetyl-L-carnitine and ALCAR.

A chemical reaction in which a small molecule called an acetyl group is added to other molecules. Acetylation of proteins may affect how they act in the body.

A chemical made by some types of nerve cells. It is used to send messages to other cells, including other nerve cells, muscle cells, and gland cells. It is released from the nerve ending and carries signals to cells on the other side of a synapse (space between nerve cells and other cells). Acetylcholine helps control memory and the action of certain muscles. It is a type of neurotransmitter.

A drug usually used to reduce the thickness of mucus and ease its removal. It is also used to reverse the toxicity of high doses of acetaminophen. Also called N-acetyl-L-cysteine and N-acetylcysteine.

Clusters of abnormal tube-like glands in the lining of the colon and rectum. ACF form before colorectal polyps and are one of the earliest changes that can be seen in the colon that may lead to cancer. Also called aberrant crypt foci.

A lack of hydrochloric acid in the digestive juices in the stomach. Hydrochloric acid helps digest food.

A chemical that gives off hydrogen ions in water and forms salts by combining with certain metals. Acids have a sour taste and turn certain dyes red. Some acids made by the body, such as gastric acid, can help organs work the way they should. An example of an acid is hydrochloric acid. Acidity is measured on a scale called the pH scale. On this scale, a value of 7 is neutral, and a pH value of less than 7 to 0 shows increasing acidity.