What is the term used when an organism decreases in size?

The term that describes the process of an organism or an organ decreasing in size is atrophy. Atrophy occurs as a result of various factors, including decreased workload, loss of stimulation, inadequate nutrition, or loss of innervation. This reduction in size may affect the entire organism or specific tissues and organs, leading to a decrease in their functional capacity and overall health.

Hypertrophy, in contrast, refers to an increase in the size of an organ or tissue, typically due to increased workload or stimulation. Necrosis is the term for the death of cells or tissues in a living organism, often as a result of injury or lack of blood flow, while hyperplasia refers to the increase in the number of cells leading to tissue enlargement, which is not directly related to a decrease in size. Understanding these terms is crucial for recognizing the physiological changes that can occur in living organisms.