Sunday, January 15, 2006

wearing out theory

The oldest theory of aging is the "wearing out" theory. This theory proposes that the body wears out just as a car does. Molecules and cells within the body that are meant to last a lifetime and are not usually replaced begin to degenerate. Nerve cells do not regenerate and nor do the collagen molecules that hold the body's skin and organs together. When these are damaged, their function is lost.
The body has compensatory mechanisms. For example, when brain neurons, or nerve cells, die, adjacent nerves send out branches to fill in the space and make new connections. These compensatory responses have limits, however. Eventually, too many nerve cells are lost for adjacent ones to take over lost connections.
See also AGING, BIOLOGICAL THEORY OF.
Maranto, G. "Aging: Can We Slow the Inevitable," in Aging, Goldstein, E. C., ed. Vol. 2, Art. 78. Boca Raton, Fl.: Social Issues Resource Series, Inc., 1981.
Thompson, L. "After Age 30, Survival Is Infinite," in Aging, Goldstein, E. C., ed. Vol. 3, Art. 17. Boca Raton, FI.: Social Issues Resource Series, Inc., 1981.

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