The Aging Body

The average life expectancy has increased dramatically in the United States. A male child born in 1900 could expect to live only 46 years, whereas one born today can expect to live more than 72 years. A female child born in 1900 could expect to live 48 years, whereas one born today can expect to live about 79 years.

Despite the increase in average life expectancy, the maximum life span the oldest age to which people can live has changed little since records have been kept. Despite the best genetic makeup and medical care, no one seems to live much beyond 120 years.

Theories of Aging

Every species ages, undergoing noticeable changes from birth to death. Scientists have developed theories for why people age, although no theory has been proven. Ultimately, parts of each theory may explain why people grow old and die.

With the programmed senescence theory, the rate at which a species grows old is predetermined by its genes. Genes determine how long cells live. As cells die, organs begin to malfunction and eventually cannot maintain the biologic functions necessary to sustain life. Programmed senescence helps preserve a species; older members die at a rate that allows room for the young. The free radical theory says that cells age as a result of accumulated harm from ongoing chemi-cal reactions within cells. During these ongoing chemical reactions, toxins called free radicals are produced. The free radicals ultimately damage the cells and cause a person to age. With age, more and more damage is done until many cells cannot function normally or have died. When that happens, the body dies. Different species age at different rates depending on how cells produce and respond to free radicals.

Bodily Changes

The human body changes in many noticeable ways with age. Perhaps the first sign of aging occurs when the eye cannot focus easily on close objects (presbyopia). Often by age 40 or so, many people find it difficult to read without using glasses. Hearing also changes with age. People tend to lose some ability to hear the highest pitched tones (presbycusis). Therefore, older people may find that violin music no longer sounds as exciting as it did when they were younger. Also, because most of the closed consonants of speech are high tones (sounds such as k, t, s, p, and ch), older people may think that others are mumbling.

In most people, the proportion of body fat in-creases by more than 30 percent with age. The distribution of fat also changes: There is less fat under the skin and more in the abdominal area. Thus, skin becomes thinner, wrinkled, and more fragile, and the shape of the torso changes.

Not surprisingly, most internal functions also decline with age. These functions generally peak shortly before age 30 and then begin a gradual but straightline decline. Even with this decline, however, most functions remain adequate throughout life, because most organs have considerably more functional capacity than the body needs (functional reserve). For example, even if half the liver is destroyed, more than enough liver tissue remains to maintain normal function. Disease, rather than normal aging, usually accounts for loss of function in old age. Even so, the decline in function means that older people are more likely to experience adverse effects from drugs, changes in the environment, toxins, and illness.

Although the decline in function of many or-gans has little effect on how people live, the decline in some organs can greatly affect health and wellbeing. For example, although the amount of blood that the heart can pump at rest is not greatly reduced in old age, the heart cannot pump as much when pushed to its maximum. This means that older athletes will not be able to perform as well as younger athletes. Changes in kid-ney function can dramatically affect how well older people are able to eliminate certain drugs from their body.

Determining which changes are purely age related and which are the result of how a person has lived is often difficult. A sedentary lifestyle, poor diet, cigarette smoking, and alcohol and drug abuse can damage many body organs over time, often more so than aging alone. People who have been exposed to toxins may experience a more significant or more rapid decline in the function of some organs, especially the kidneys, lungs, and liver. People who worked in loud environments are likely to lose more of their hearing.

Some changes can be prevented by changing to a healthier lifestyle. For example, stoppingsmoking at any age, even in one's 80s, helps improve lung function and decrease the chance of developing lung cancer. Weight bearing exercise helps maintain muscle and bone strength regardless of age.

Implications of Illness

Geriatrics is the medical care of elderly people. Gerontology is the study of aging. There is no specific age at which a person becomes "elderly," although traditionally that age has been set at 65, because that is when working adults have tended to retire.

A number of disorders, sometimes called the geriatric syndromes or geriatric diseases, occur almost exclusively in older adults. Other disorders affect people of all ages but are more common or more severe or cause different symptoms or complications in the elderly.

Elderly people often experience illness differ-ently than do younger adults. A disease may cause different symptoms in elderly people. For example, an underactive thyroid gland usually causes younger people to gain weight and feel sluggish. In the elderly, an underactive thyroid gland may also produce confusion that can be mistaken for dementia. An overactive thyroid usually causes younger people to become agitated and lose weight; in the elderly, it may cause them to become sleepy, withdrawn, depressed, and confused. Depression usually causes younger adults to become tearful, withdrawn, and noticeably unhappy. In the elderly, depression some-times causes confusion, loss of memory, and ap-athy, all of which may be mistaken for dementia.

Acute illnesses such as heart attacks, hip fractures, and pneumonia were once likely to result in death for older adults. Now these illnesses are often treatable and controllable even when they are not curable. In turn, a chronic illness no longer necessarily means disability. Many people with diabetes, kidney problems, heart disease, and other chronic illnesses now find that they can remain functional, active, and independent.

Sociologic and economic factors often change the way the elderly seek and receive care. Many elderly people tend to conceal minor problems and don't seek medical care until the problems become major. Elderly people tend to have more than one disease at a time, and those diseases may have an impact on each other. For example, depression may make dementia worse, and diabetes may make an infection more severe.

Sociologic factors often complicate disease in the elderly. If illness leads to some temporary or permanent loss of independence, an older person may become depressed and need both social services and psychologic help. For these reasons, geriatricians often recommend multidisciplinary care. With this type of care, a team of medical personnel, which may consist of doctors, nurses, social workers, therapists, pharmacists, and psychologists, plan and implement care under the leadership of a primary doctor.

Submitted By
Professor Joanne l.

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