[Normal aging--causes, consequences]

Genetic mechanisms influence the aging process. The DNA-repair influences the longevity of a species, and the DNA molecule may be altered by free radicals. Cellular degeneration because of aging occurs in subpopulations of cells, and leads to age changes in the tissues, organs and the whole organism. There is a hierarchy in the way functional capacity declines in old age. Normal and pathological changes are difficult to distinguish in old age. Multi organ failure may lead to vague disease manifestations. In old individuals there is often degenerative age changes in many vital organs, but no definite cause of death found by autopsy. In order to improve the functional ability, individual training is one strategy, the other is to adjust the environments to improve the coping ability despite of disease and old age.