cellhypertrofi

Cellhypertrofi, or cellular hypertrophy, is the process by which individual cells increase in size, resulting in a larger tissue or organ without a corresponding rise in cell number. This distinguishes hypertrophy from hyperplasia, where tissue growth mainly comes from more cells rather than larger cells.

Causes and types. Hypertrophy can be physiological or pathological. Physiological hypertrophy occurs with increased functional demand, such as skeletal muscle enlargement in response to resistance training or healthy cardiac remodeling in athletes. Pathological hypertrophy arises from chronic stress or hormonal imbalances, for example left ventricular hypertrophy due to sustained hypertension or valve disease, and can compromise organ function if progression continues. Adipose tissue and some other tissues can exhibit hypertrophy in response to excess nutrient supply, notably seen in obesity.

Mechanisms. The enlargement of cells is usually driven by increased protein synthesis and, in some contexts, reduced protein degradation. Key signaling pathways include the PI3K-Akt-mTOR axis, which promotes protein assembly, and the calcineurin-NFAT pathway in cardiac muscle. Mechanotransduction, involving changes in the cytoskeleton and cell-matrix interactions, also contributes by translating mechanical load into growth signals. Growth factors such as IGF-1 play supporting roles in promoting hypertrophic growth.

Clinical and laboratory aspects. Hypertrophy is often detected by imaging or histology showing enlarged cell size and thickened tissue structures. It can be reversible if the underlying stimulus is removed, especially in physiological settings. However, long-standing pathological hypertrophy may lead to tissue dysfunction and heart failure, making management focus on treating the underlying cause and mitigating progression.