Hypertrophy

Hypertrophy is a term describing an increase in the size of cells. It occurs due to an increase in synthesis of intracellular proteins and other cellular components, often in response to an invoking stimulus/stress, which will result in an increase in the size of an organ.

This is in contrast to hyperplasia, which is an increase in the number of cells, although both processes frequently co-occur.

Hypertrophy can be physiological or pathological. Physiological hypertrophy occurs due to increased utility of an organ or stimulation by growth factors and hormones. For example, increased use of skeletal muscle results in hypertrophy. Physiological hypertrophy can also be seen secondary to growth factors in the gravid uterus, which enlarges to accommodate a growing fetus .

Pathological hypertrophy occurs due to stimulation secondary to a pathological mechanism. The initial result may be adaptive to overcome stress, however the end result is maladaptive when compensatory mechanisms fail. For example, cardiac hypertrophy occurs secondary to hypertension and hemodynamic overload, which eventually results in heart failure when myocyte enlargement is unable to compensate for increased cardiac burden .