aging [L, aetas, lifetime] , the process of growing old. Biological aging results in part from a failure of body cells to function normally or to produce new body cells to replace those that are dead or malfunctioning. Normal cell function may be lost through infectious disease, malnutrition, exposure to environmental hazards, or genetic influences. Among body cells that exhibit early signs of aging are those that normally cease dividing after reaching maturity. Sociological and psychological theories of aging seek to explain the other influences on aging caused by the environment, engagement, personality, and nonbiological influences. Promoting health through attention to exercise, nutrition, and stress management is a key factor in maintaining body systems and mental health. See also assessment of the aging patient.
