Atom
Atom: The smallest part of any material that cannot be broken up by chemical means. Each atom has a center (the nucleus) which contains protons and neutrons. Electrons orbit around the nucleus. The atom is primarily empty space.
If the nucleus of an atom were the size of the button on a baseball pitcher’s cap, the electrons would be like dust particles revolving around the outside of the baseball stadium.
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- Atonia, REM sleep
Atonia, REM sleep: See: Sleep paralysis Medically reviewed by Martin Zipser, MD; Board Certified: Surgery
- Atonic
Atonic: Without normal muscle tone or strength. An atonic seizure is one in which the person suddenly loses muscle tone and strength; the person cannot sit or stand upright and, unless supported, falls down.
- Atonic seizure
Atonic seizure: A seizure in which the person suddenly loses muscle tone and strength and, unless supported, falls down. Also called drop attack or drop seizure. Atonic means a lack of muscle tone and strength.
- Atopic
Atopic: A predisposition toward developing certain allergic hypersensitivity reactions. Atopy may have a hereditary component, although contact with the allergen must occur before the hypersensitivity reaction can develop.
- Atopic dermatitis
A skin disease characterized by areas of severe itching, redness, scaling, and loss of the surface of the skin. Atopic dermatitis is the most common of the many types of eczema. Atopic dermatitis is frequently associated with other allergic disorders, especially asthma and hay fever. A defect of the immune system within the skin has […]