Dictionary

anus, imperforate A birth defect in which the rectum is a blind alley and there is no anus. Imperforate anus occurs in about 1 in 5,000 births, and it can be corrected by surgery.

anus The opening of the rectum to the outside of the body.

antrum A general term for a nearly closed cavity or chamber. For example, the antrum of the stomach (gastric antrum) is a portion before the outlet, which is lined by mucosa and does not produce acid. The paranasal sinuses can be referred to as the frontal antrum, ethmoid antrum, and maxillary antrum.

antro-duodenal motility study A study used to detect and record the contractions of the muscles of the stomach and duodenum in order to diagnose motility disorders of the stomach and small intestine. A tube is passed through the nose, throat, esophagus, and stomach, until the tip lies in the small intestine. The tube senses when…

antiviral agent A medication or another agent that kills viruses or inhibits their capability to reproduce.

antitoxin 1 An antibody that is naturally produced to counteract a toxin, such as a toxin from a bacterial infection or snake bite. 2 An antibody from the serum of an animal stimulated with specific antibodies that is administered to humans or other animals to provide passive immunity to a disease. Such antitoxins are of…

antispasmodic A medication that relieves, prevents, or lowers the incidence of muscle spasms, especially those of smooth muscle such as in the bowel wall.

antiseptic Discouraging the growth of microorganisms. Commonly refers to antiseptic preparations used during medical procedures or used to maintain sanitary conditions in nursing homes, barbershops, tattoo parlors, and other facilities where unchecked microorganism growth could result in disease. See also aseptic.

antiplatelet agent A medication that interferes with the tendency of platelets in the blood to clump and clot. Aspirin is an antiplatelet agent.

antioxidant A substance that reduces damage due to oxygen, such as that caused by free radicals. Well-known antioxidants include enzymes and other substances, such as vitamin C, vitamin E, and beta carotene, which are capable of counteracting the damaging effects of oxidation. Antioxidants are also commonly added to food products such as vegetable oils and…

antinuclear antibody An antibody that is directed against the structures within the nucleus of a cell and that is characteristic of autoimmunity. Abbreviated ANA. ANAs are found in the blood of patients whose immune systems attack their own body tissues (autoimmunity), such as patients with systemic lupus erythematosus, rheumatoid arthritis, juvenile diabetes mellitus, and Hashimoto…

antineoplastic 1 Acting to prevent, inhibit, or halt the development of a neoplasm (a malignant tumor, or cancer). 2 An agent with antineoplastic properties. Cancer chemotherapy is antineoplastic.