What does the term "atrophy" refer to?

Atrophy refers to the process of a body part or tissue wasting away or decreasing in size due to various reasons such as reduced use, lack of nutrients, or neuromuscular disorders. This term is often used in medical contexts to describe muscles or organs that have shrunk due to inactivity, aging, or disease. For example, a muscle might atrophy if it is not exercised regularly, leading to a significant decrease in muscle mass and strength. This concept is crucial in healthcare as it helps in understanding certain medical conditions and guiding treatment plans, especially in rehabilitation settings where maintaining or improving muscle mass is important for recovery.

The other options—such as increasing in size, swelling, and stiffness—represent different physiological changes that do not align with the definition of atrophy. Increasing in size would be indicative of hypertrophy, swelling typically refers to inflammation or an accumulation of fluid, and stiffness can be associated with joint or muscle issues without implying a decrease in size. Therefore, decreasing in size is the defining characteristic that aptly describes atrophy.