General pathology · Cell injury, adaptation and death
Hypertrophy: physiologic and pathologic !
- Process
Hypertrophy is growth of an organ because its cells get bigger, not more numerous. The heart and muscles do this when they work harder.
Updated 2026-11-01
What it is
Hypertrophy is an increase in cell size, with more structural proteins and organelles, that enlarges the organ. It is typical of cells that divide little, such as heart and skeletal muscle. It can be physiologic (athletes, the pregnant uterus) or pathologic (heart under pressure or volume overload). Hypertrophy has a limit: an overloaded heart eventually develops myocyte injury, fibrosis and failure.
Structure
- Gross: thick ventricular wall; heavy heart.
- Microscopic: enlarged myocytes with large, dark, often box-shaped nuclei.
- In hypertrophic cardiomyopathy: myocyte disarray and interstitial fibrosis.
Step by step
- Workload rises (high blood pressure, aortic stenosis, exercise) and stretches the myocytes.
- Stretch sensors, growth factors and hormones activate intracellular signalling.
- Transcription factors (such as GATA4, NFAT and MEF2) switch on growth genes.
- More contractile proteins and sarcomeres are made; the cell enlarges and generates more force.
- If overload persists, capillary supply and energy production lag behind.
- Myocytes degenerate, fibrosis develops and the ventricle stiffens and fails.
Physiologic vs pathologic hypertrophy of the heart
| Feature | Physiologic (athlete) | Pathologic (disease) |
|---|---|---|
| Cause | Training, intermittent load | Chronic pressure or volume overload, mutations |
| Function | Normal or better | Diastolic dysfunction, then systolic failure |
| Fibrosis | No | Yes |
| Reversibility | Regresses when training stops | Partly reversible if the cause is treated early |
| Gene program | Adult isoforms preserved | Fetal genes re-expressed |
Clinical notes
- Left ventricular hypertrophy from hypertension is an independent risk factor for heart failure, arrhythmia and sudden death.
- Hypertrophic cardiomyopathy is inherited (usually sarcomere gene mutations) and a cause of sudden death in young athletes.
Test yourself
Think of the answer, then tap the question to see it.
Why does the heart respond to overload by hypertrophy rather than hyperplasia?
Adult cardiac myocytes have very limited capacity to divide, so they adapt by enlarging.
What type of hypertrophy does chronic hypertension cause?
Concentric left ventricular hypertrophy, with a thick wall and normal or small chamber.
What changes mark pathologic rather than physiologic cardiac hypertrophy?
Fibrosis, re-expression of fetal genes and progressive dysfunction leading to heart failure.
Related
- Hyperplasia: physiologic and pathologic
- Atrophy
- Metaplasia
- Intracellular accumulations: cholesterol, proteins, hyaline, glycogen
Related conditions
- Hypertensive heart disease
- Hypertrophic cardiomyopathy
- Arterial hypertension
- Aortic Valve Stenosis
- Heart failure
- Pulmonary hypertension and cor pulmonale
- Acromegaly and gigantism
- Coarctation of the aorta
Elsewhere in DurgiPedia
- Cell adaptations: hypertrophy, hyperplasia, atrophy, metaplasia
- Muscle hypertrophy, atrophy and remodeling
- Heart failure physiology
- Preload, afterload and contractility
- Physiology of hypertension
- Cardiac muscle: intercalated discs
- Smooth muscle
Educational content on the mechanisms of disease; not a diagnostic or treatment guide and no substitute for a health professional's advice. No doses are given.
Sources: Hypertensive heart disease: MedlinePlus Medical Encyclopedia (MedlinePlus, US National Library of Medicine, 2024); Hypertrophic cardiomyopathy: MedlinePlus Medical Encyclopedia (MedlinePlus, US National Library of Medicine, 2024); 4.6 Tissue Injury and Aging (OpenStax (Rice University), 2022).
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Representative model, for educational purposes only.