The
aging process takes place as changes occur in both individual cells as
well as whole organs. These changes result in changes in both
appearance and functioning, resulting in the process of aging.
Aging cells:
Aging takes place
over a period of time and eventually we begin to function less well.
Cells begin to die as a normal process of our body’s functioning. They
may die due to their inability to divide normally or as a result of
being damaged. They may be damaged by harmful substances in the
environment such as radiation, sunlight, and even medications such as
chemotherapy drugs. Also, they may be damaged by certain by-products
of their own cellular processes. We frequently hear of these
by-products being referred to as free radicals, which are given off
when cells produce energy.
Many cells also
die because they're programmed to do so. This programmed death of the
cell is called apoptosis and is a normal part of the aging
process. Some experts have referred to this as somewhat of a cell
suicide in which old cells are replaced by new cells and then
excess cells are eliminated.
Aging and cell
death is also affected by the fact that cells can only divide a
limited number of times. This limit is also a part of the normal
processes programmed by your genes. When cells can no longer divide
they get larger, exist for a while and then die. This limited cell
division involves a structure called a telomere. Telomeres are
used to move the cell’s genetic material in preparation for cell
division. Each and every time that a cell divides the telomeres
become shorter. Eventually they become so short that the cells can no
longer divide. An interesting caveat is that the telomeres of cancer
cells unlike those of normal cells, do not shorten each time that the
cell divides and consequently cancer cells can divide forever.
Aging organs:
The aging process
is also intimately affected by the functioning of bodily organs.
Organ functioning is also affected by how well the cells within a
specific organ functions. Older cells obviously function less well
than younger ones. Also, in some organs, cells die and are no longer
replaced resulting and a fewer number of cells within that organ. The
aging process takes a significant toll on the number of cells within
the testes, ovaries, liver, and kidneys. They decrease markedly as we
age. When the number of cells actually becomes too low the organ
cannot function normally. Most organs function less well as people get
older. However, some organs do not necessarily lose significant
numbers of cells. The brain is a good example of this. Researchers
are now beginning to conclude that healthy older people do not usually
lose many brain cells. Substantial brain cell losses are usually the
result of a disease process such as Alzheimer's disease or
Parkinson's.
The aging effect
on one organ system will also affect the surrounding organs. As an
organ begins to decline in functioning, whether due to a disorder or
to the aging process itself, it can also affect the functioning of
another related organ. For example, if atherosclerosis narrows the
blood vessels to the kidneys, the kidneys function less well as there
is a reduced amount of blood flowing to them.
Some information
from the Merck Manual of Health and Aging
Additional
information and web page by
Paul Susic M.A. Licensed Psychologist
Ph.D. Candidate (Health Psychology)
