What term is used to refer to the aging process of each body system?

The term that accurately refers to the aging process of each body system is "age-related changes." This term encompasses the physiological alterations that occur in the body as a person ages. It highlights that these changes are not simply due to the passage of time but also involve a variety of biological factors that affect the functioning and structure of various systems in the body.

While "aging process" might seem like a suitable option, it is somewhat vague compared to "age-related changes," which specifically denotes how aging impacts different body systems. "Developmental changes" typically refers to the progression from childhood to adulthood and does not focus on the modifications that occur specifically due to aging. The term "life cycle" also refers more broadly to the stages of life a person goes through from birth to death and does not emphasize the specific changes resulting from aging.

Thus, "age-related changes" is the most precise term used to describe the transformations that occur within the body systems as a person grows older.