Causes of Atrophy and Hypertrophy

Non-neoplasia. A: Normal cells, B: Atrophy, C:... — Non-neoplasia. A: Normal cells, B: Atrophy, C: Hyperplasia, D: Hypertrophy, E: Metaplasia and F: Dysplasia. Hematoxylin eosino staining. (Photo credit: Wikipedia)

What is Atrophy?

Atrophy is a type of cellular adaptation. It is generally a reversible process.

Atrophy is a decrease in the size of a cell or tissue.
The decreased size of a cell or tissue results in decreased oxygen consumption.
The metabolic needs of the cells get reduced.
The overall efficiency of the cell function gets increased.
Atrophy is irreversible if it is caused by nervous innervation of the tissues.

Causes of Atrophy:

Prolonged bed rest
Disuse of limbs
Disuse of tissues
Poor nutrition of the tissues
Ischemia

What is Hypertrophy?

Hypertrophy is a kind of cellular adaptation in response to the changes in the surrounding fluid environment, when the cells are exposed to the numerous stimuli.

In hypertrophy, there will be an increase in the cell size.
Tissue mass also increases in hypertrophy.
If there is an increase in the workload to a cell or a tissue, hypertrophy occurs.
Hypertrophy occurs in tissues that cannot increase cell number as an adaptive response.
It may be a normal physiological response, such as increase in cell mass as seen with exercise.
It may also be pathologic as in case of cardiac hypertrophy, which is seen with prolonged hypertension.
It may also be a compensatory process. When one kidney is removed, the other kidney hypertrophies to increase the functional capacity.