What are the types of cellular adaptation?

Adaptations are reversible changes in the size, number, phenotype, metabolic activity, or functions of cells in response to changes in their environment.
Cellular adaptation is mainly of four types:

1. Hypertrophy: Hypertrophy refers to an increase in the size of cells, that results in an increase in the size of the affected organ.
2. Hyperplasia: Hyperplasia is defined as an increase in the number of cells in an organ or tissue in response to a stimulus.
3. Atrophy: Atrophy is defined as a reduction in the size of an organ or tissue due to a decrease in cell size and number.
4. Metaplasia: Metaplasia is a reversible change in which one differentiated cell type (epithelial or mesenchymal) is replaced by another cell type.