A model of bioenergetic aging According to the free radical theory of aging, the buildup of oxidative stress and oxidative damage causes age-related degeneration. Since mitochondrial DNA and the cellular respiratory chain are highly susceptible to oxidative damage, this theory complements the bioenergetic theory of aging proposed by Linnane. Figure 2 illustrates how these theories might fit together. The bioenergetic theory of aging Figure 1. The series of boxes on the bottom shows how mitochondrial deterioration can hasten aging and degeneration, as proposed by Linnane.
Mitochondria are highly susceptible to oxidative stress, which reinforces the other factors.
When Cellular Energy Declines Figure 2. Cell undergoing programmed cell death. As the cell shrinks and then fragments, its organelles remain relatively intact and enclosed by membranes. Neighboring cells or macrophages safely digest the fragments. By contrast, in necrotic cell death the cell swells and ruptures, organelles disintegrate, and inflammation tends to occur.