USMLE (United States Medical Licensing Examination) Step 1 Practice Exam

The accumulation of lipofuscin pigment within cardiac myocytes is indeed a notable change associated with normal aging. Lipofuscin is a brownish pigment that represents cellular debris and is often referred to as "wear-and-tear" pigment. It accumulates in cells over time due to the degradation of cellular components and is particularly common in postmitotic cells, such as cardiac myocytes. This process reflects the cumulative effects of oxidative stress and reduced autophagic activity in aging cells, leading to an increase in the amount of storage material within the myocytes.

Other changes in the heart due to aging, while they may be related, do not align as directly with normal aging processes. For instance:

- Increased left ventricular chamber size can occur with aging but often is more pronounced in individuals with certain cardiovascular conditions rather than being a direct result of aging alone.

- Thickening of the ventricular septum is associated with age-related physiological changes, but it is also linked to conditions like hypertension, making it less definitive as a pure aging change.

- An increase in myocardial atrophy is typically seen as a consequence of disuse or certain pathological conditions, rather than being a standard aspect of aging.

Understanding these changes highlights how the heart adapts over time and