What
does it mean to grow older?
Until you're in your fourth or fifth decade of life, the
finality of aging may not mean a lot to you even though
it's a lifelong process. Childhood, adolescence and young
adulthood are typically filled with feelings of immortality.
It's often only when you start to notice physical changes
in yourself that you accept that you're actually getting
older.
If you're older than 60, you've probably already encountered
these realities of aging, but you may also have realized
that you have a lot more life left than you'd once thought.
So what exactly is aging - what causes it, how does your
body change and how long can you expect to live?
What causes aging?
The
causes of aging are not fully understood, but most scientists
theorize that aging is probably the result of a combination
of factors including your genes, your environment and your
lifestyle. According to the National Institute on Aging,
theories of aging are generally grouped into two categories:
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"Programmed"
theories. These
theories suggest that biological factors or programs
in your body cause aging to occur on a set timeline.
For example, one theory suggests that your immune system
is responsible - it's programmed to decline, leading
to disease and therefore aging and death. Another points
to your hormones, proposing that - throughout your life
- programmed changes in the production of hormones regulate
your aging.
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Damage
or error theories.
Theories in this group explain aging as a result of
environmental factors that gradually damage your body
and interfere with its normal function. For example,
the wear-and-tear theory suggests that the cells and
tissues in your body have essential parts that simply
wear out over time. Another theory indicates that byproducts
of your cells' normal metabolism (free radicals) damage
the ability of your cells to work normally until eventually
your organs no longer work. Environmental factors such
as sunlight and toxins can also cause free radicals
that trigger wear. Other theories suggest that genetic
mutations or impaired protein synthesis - the process
by which your cells produce protein - are behind damaged
cells. |
Scientists
use these theories to study aging. Their research may one
day help slow the aging process, extend human life, and
keep you active and healthy for longer.
How does your body
change?
You've
most likely noticed some of the physical effects of aging
- wrinkles, gray hair and slower reflexes - but what else
is going on that you're not seeing? As you age, time takes
its toll on the organs and systems in your body. How and
when this occurs is unique to you. And everyone doesn't
undergo the same changes. Still, in general, some of the
age-related changes that occur include changes in your:
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Bones.
As you age, your bones become less dense as they slowly
lose mass and minerals. Gradual loss of density weakens
your bones and makes them more susceptible to fracture.
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Brain.
The number of neurons (cells) in your brain decreases.
However, in some areas of your brain, the number of
connections between cells increases, perhaps helping
to compensate for the cellular decrease and maintain
normal brain function.
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Cardiovascular
system.
The size of your heart increases slightly. Your blood
pressure increases, your maximum heart rate decreases
and your heart may take longer to return to its normal
resting state after physical activity.
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Hearing.
The normal wear and tear of sounds over the years can
damage the cells of your inner ears. The walls of your
auditory canals also thin, and your eardrums thicken.
You may have greater difficulty hearing higher frequencies.
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Kidneys.
The size of your kidneys shrinks, and the amount your
bladder can hold decreases. Your kidneys also become
less efficient at removing wastes from your blood.
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Muscles.
Muscle mass and strength decrease, though increased
physical activity can reduce this effect. The amount
of water in your tendons and ligaments decreases, increasing
stiffness.
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Reproductive
system.
Women produce less estrogen, progesterone and testosterone
as they age. The uterus and the vagina shrink, and there's
less vaginal lubrication. Men produce less sperm, and
their levels of testosterone decrease.
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Skin.
Your skin thins, and your nails grow at about half the
pace they once did. Your sweat and oil (sebaceous) glands
become less active, and the moisture in your skin decreases.
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Vision.
Your eyes are less able to produce tears, your retina
thin and your lenses yellow. In your 40s, focusing on
objects that are close-up becomes more difficult due
to changes in your lenses. Later, your irises stiffen,
making your pupils less responsive. This can make it
more difficult to adapt to different levels of light.
Further changes to your lenses can make you sensitive
to glare. |
How long can you live?
One
hundred twenty-two years is the longest documented human
life span. Though a life span this long is rare, improvements
in medicine, science and technology in the last century
have helped more people live longer, healthier lives. In
the early 1900s the average life expectancy in the United
States at birth was only about 50 years. Today, it's close
to 77.
Moreover, the 85-plus group is the fastest-growing demographic
segment in the United States, although the number of people
100 and older has exploded as well. The U.S. Census Bureau
projects that the number of people age 85 and older could
increase from 4 million in 2000 to 19 million by 2050. And
the number of people age 100 and older is projected to more
than quadruple from 65,000 in 2000 to 381,000 in 2030.
In the last 10 years, scientists have made great progress
in the study of aging. Currently, thousands of research
projects on how to slow aging are under way in numerous
medical specialties throughout the world. Scientists are
studying a variety of topics including everything from cloning
for spare parts to how DNA mutations affect aging to fighting
cancer with viruses.
But longer lives also mean that some people may spend more
time in an incapacitated state at the end of their lives,
in part because the United States has done too little to
promote healthy aging. Rates of obesity, sedentary lifestyle,
smoking and alcohol abuse are still too high. However, researchers
say it's never too late to clean up your act. For example,
if you quit smoking, your risk of heart disease begins to
fall almost immediately. Living a healthy lifestyle can
improve how you age. No matter what your age, you can begin
preparing now for your later years. You are the master of
your own quality of life.
Clearly, old isn't what it used to be. And as more than
70 million baby boomers approach their retirement years,
the definition continues to evolve.
You
may get more information at http://www.cdc.gov/aging/health_issues.htm
and here are the links below to learn more about your health.
