Hypertrophy
Say it: hy-PUR-truh-fee
Hypertrophy is the enlargement of a tissue or organ because its individual cells grow larger, rather than because the number of cells increases.
Definition
What is hypertrophy?
Hypertrophy is an increase in the size of an organ or tissue caused by an increase in the size of its cells. The cells grow by making more structural proteins and organelles; muscle fibers, for example, add myofibrils and sarcomeres, which lets them produce more force. It differs from hyperplasia, in which a tissue grows by adding cells, although the two often occur together in tissues whose cells can still divide.
Hypertrophy is the main way that tissues made of cells that rarely or never divide, such as skeletal and heart muscle, can enlarge. It is triggered by a heavier workload and by growth factors and hormones. Physiological hypertrophy is healthy: resistance training thickens skeletal muscle fibers, endurance training enlarges an athlete's heart, and the smooth muscle of the uterus grows enormously in pregnancy, partly by hypertrophy and partly by hyperplasia.
Pathological hypertrophy is a response to strain. Long-standing high blood pressure or a narrowed aortic valve forces the left ventricle to pump against greater resistance, so its wall thickens, a change called left ventricular hypertrophy. This compensates at first, but the stiff, thickened muscle outgrows its blood supply and can lead to heart failure and abnormal rhythms. Hypertrophic cardiomyopathy is a mostly inherited disease in which heart muscle thickens without such a cause.
Word parts
Where does the word “hypertrophy” come from?
- hyper-
- over, excessiveGreek hyper
- troph-
- nourishment, foodGreek trophe
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Terms that go with it
- AtrophyAtrophy 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.
- HyperplasiaHyperplasia is the enlargement of a tissue or organ through a rise in its number of cells, which still look normal under the microscope.
- SarcomereA sarcomere is the repeating contractile unit of striated muscle, the section of a myofibril between two Z-discs where actin and myosin interact.
- Skeletal muscleSkeletal muscle is the striated, voluntary muscle tissue attached to bones by tendons that moves the body, holds posture and produces heat.
- HypertensionHypertension is a long-term condition in which the pressure of blood against artery walls stays higher than normal, straining the heart and vessels.
- Heart failureHeart failure is a long-term condition in which the heart fails to pump as much blood as the body needs, even though it has not stopped beating.
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Checked against
Written for biofideX in plain words, after checking these references:
- NCBI MeSH: Hypertrophy
- OpenStax Anatomy and Physiology 2e, 10.6 Exercise and Muscle Performance
- NHLBI: Types of Cardiomyopathy
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