Glossary: Chronic Fatigue
Content provided by the Faculty of the Harvard Medical School
Glossary
adenosine triphosphate (ATP): The molecule that carries energy for all cells.
anemia: A decline in the number of red blood cells or the amount of hemoglobin in the blood, which lowers the oxygen-carrying capacity of the blood.
chronic fatigue syndrome (CFS): A disorder characterized by at least six months of fatigue, together with impaired concentration or memory and other symptoms.
circadian cycle: The innate biological clock that regulates sleep and waking and that controls the daily ups and downs of physiologic patterns, including body temperature, blood pressure, and the release of hormones.
fatigue: A decrease over time in the ability to perform a physical or mental task. It includes muscle fatigue as well as central fatigue, which originates in the central nervous system and influences the perception of fatigue.
fibromyalgia: A disorder characterized by pain and tenderness in muscles and joints, as well as by fatigue. Similar in many respects to chronic fatigue syndrome.
glucose: A simple sugar that circulates in the bloodstream and serves as a source of energy for cell metabolism. It's formed mainly by the digestion of carbohydrates.
hypothalamus: The part of the brain that controls the autonomic nervous system and that regulates sleep, appetite, body temperature, and other biological states.
insomnia: The inability to fall asleep or remain asleep long enough to feel rested.
insulin: The hormone that carries glucose from the blood into the cells.
mitochondria: Often called the body's energy factories, these small, threadlike structures within the cell's cytoplasm are where ATP, the energy molecule, is made.
myelin: A fatty material that surrounds and protects some types of nerve fibers.
neuromuscular junction: A tiny space between the end of a nerve and the surface of a muscle.
non-REM sleep: The type of sleep that includes deep sleep, the period considered most important for preventing daytime fatigue.
rapid eye movement (REM) sleep: A period of intense brain activity during sleep, often associated with dreams; named for the rapid eye movements that occur during this time.
suprachiasmatic nucleus: A small group of nerve cells that controls the sleep/wake cycle; located in the hypothalamus.
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| Last updated: | January 23, 2007 |
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Medical content reviewed by the Faculty of the Harvard Medical School. Harvard Health Publications, Copyright © 2007 by President and Fellows of Harvard College. All rights reserved. Used with permission of StayWell.
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