Atrophy
Say it: A-truh-fee
Atrophy is the shrinking of a cell, tissue or organ that had reached normal size, usually as cells lose substance in response to reduced demand or support.
Also: atrophies
Definition
What is atrophy?
Atrophy is a decrease in the size of a tissue or organ that had previously grown to its normal size. Usually each cell shrinks because it breaks down more of its own proteins and organelles than it builds, through the ubiquitin-proteasome system and autophagy; if the stress continues, some cells also die and are not replaced. Atrophy is one of the classic cellular adaptations, alongside hypertrophy, hyperplasia and metaplasia, and shrunken cells can keep working, though at a lower level.
Common causes include disuse, as in a limb held in a cast or a person confined to bed; loss of the nerve supply to a muscle, as after a nerve injury; reduced blood flow; poor nutrition; loss of hormonal stimulation, as when the lining of the uterus and breast tissue shrink after menopause; pressure from a growing mass; and aging. Some atrophy is a normal part of development, such as the gradual shrinking of the thymus after childhood.
Skeletal muscle shows atrophy most clearly. Wasting from disuse can often be reversed by exercise, but the age-related loss of muscle called sarcopenia cannot be fully reversed, though training slows it. In the brain, shrinkage of the cortex is a feature of Alzheimer's disease and other dementias.
Word parts
Where does the word “atrophy” come from?
- a-
- withoutGreek a-
- troph-
- nourishment, foodGreek trophe
Practice it
Where you'll meet it
Quizzes that use it
Related
Terms that go with it
- HypertrophyHypertrophy is the enlargement of a tissue or organ because its individual cells grow larger, rather than because the number of cells increases.
- HyperplasiaHyperplasia is the enlargement of a tissue or organ through a rise in its number of cells, which still look normal under the microscope.
- MetaplasiaMetaplasia is the replacement of one mature cell type by another in a tissue, usually as an adaptation to long-term irritation or injury.
- Skeletal muscleSkeletal muscle is the striated, voluntary muscle tissue attached to bones by tendons that moves the body, holds posture and produces heat.
- UbiquitinUbiquitin is a small, highly conserved protein that cells attach to other proteins as a tag, most often to mark them for destruction.
- Alzheimer's diseaseAlzheimer's disease is a progressive brain disease that destroys neurons and their connections and is the leading cause of dementia in older adults.
Sources
Checked against
Written for biofideX in plain words, after checking these references:
- NCBI MeSH: Atrophy
- OpenStax Anatomy and Physiology 2e, 10.6 Exercise and Muscle Performance
- American Heritage Dictionary: atrophy
Last updated
Spotted a mistake? Tell us and we'll correct it.
Practice Pathology
Free pathology quizzes, with an explanation for every answer.
See the Quizzes