Aromatherapy: A form of alternative medicine in which essential oils or other scents are inhaled to achieve therapeutic benefit. The mechanism of action in aromatherapy is unknown, but recent studies have shown that aromatherapy may be beneficial for some health problems.
- Arrector pili
Arrector pili: A microscopic band of muscle tissue which connects a hair follicle to the dermis. When stimulated, the arrector pili will contract and cause the hair to become more perpendicular to the skin surface (stand on end).
- Arrayed library
Arrayed library: In genetics, an arrayed library consists of (in technical terms) individual primary recombinant clones which are hosted in phage, cosmid, YAC, or another vector that have been placed in two- dimensional arrays in microtiter dishes (plastic dishes with an orderly array of tiny wells). Each primary clone can be identified by the identity […]
- Arrectores pilorum
Arrectores pilorum: Tiny muscles that act as the hair erector muscles. The arrectores pilorum play a key role in goose bumps, a temporary local change in the skin The chain of events leading to this skin change starts with a stimulus such as cold or fear. That stimulus causes a nerve discharge from the sympathetic […]
Arrhythmia: An abnormal heart rhythm. In an arrhythmia the heartbeats may be too slow, too rapid, too irregular, or too early. Rapid arrhythmias (greater than 100 beats per minute) are called tachycardias. Slow arrhythmias (slower than 60 beats per minute) are called bradycardias. Irregular heart rhythms are called fibrillations (as in atrial fibrillation and ventricular […]
- Arrhythmia, sinus
Arrhythmia, sinus: The normal increase in heart rate that occurs during inspiration (when you breathe in). This is a natural response and is more accentuated in children than adults. The “sinus” refers to the natural pacemaker of the heart which is called the sinoatrial (or sinus) node. It is located in the wall of the […]