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Biological Perspectives on Aging

  1. How do environmental hazards, developmental processes, and genetic tendencies contribute to the aging process?
    Most scientists agree that aging is probably caused by a combination of environmental, developmental, and genetic factors, but they disagree on which factors may be most important. Two theories, the wear and tear theory and the somatic mutation theory, emphasize the role of the environment. The wear and tear theory, which is based on the idea that the body is like a machine that simply wears out, is now largely discounted. The somatic mutation theory holds that environmental insults cause genetic damage, which hastens aging.
    Several other theories highlight the role of developmental processes and genetic programming. The immune function theory of aging emphasizes the gradual breakdown of the immune system as the central cause of aging. Another theory, the cross-linkage theory of aging, is based on the idea that the gradual accumulation of cross-linked collagen causes a number of bodily changes associated with aging, such as hardening of the arteries and stiffness of joints. A third theory emphasizes the role of free radicals, unstable molecules that are implicated in a number of diseases. Finally, according to genetic control theory, our life span is programmed into our genes.

  2. What is the difference between normal aging and pathological aging?
    Biological aging refers to the structural and functional changes that occur in an organism over time, beginning at maturity and lasting until death. This normal process of aging is rarely lethal on its own. Instead, aging-dependent diseases, including cancer, diabetes, heart disease, osteoporosis, and Alzheimer's disease, increase a person's vulnerability to stress and the probability of death. This increased vulnerability is called senescence. While disability rates increase as people age, most people spend most of their lives free of disability.

  3. How does aging change a person's physical appearance and mental functioning?
    As we age, a number of changes occur in the skin. Some, such as wrinkles, sagging chins, and age spots, have no health consequences. The risk of skin cancer also increases with age, because of the cumulative effects of a lifetime of exposure to the sun. Age-related changes in the nervous system, which coordinates all other body systems, can affect walking, sleep patterns, learning, and memory. As people age, they spend more time in the lighter stages of sleep and awaken more often during the night. Because of changing sleep patterns, older people are more prone to chronic insomnia. They are also more likely to fall.

  4. How does aging affect a person's sensory organs?
    As people age, they lose sensitivity to perceptual experiences associated with vision, hearing, taste and smell, and touch. Older people need more light to see clearly and may have trouble seeing in the dark. They also may have presbyopia, which refers to an inability to focus on near objects. Two visual disorders that become increasingly common with advancing years are cataracts and glaucoma. Both can be prevented or cured with proper medical treatment. As people age, their ability to receive and interpret sound declines. The loss of hearing can lead an otherwise healthy individual to become socially isolated from family and friends. Taste and smell being closely related, as people lose their ability to smell distinct odors, their sense of taste also suffers. A loss of taste in turn affects eating habits. People who can't taste their food may eat less and become malnourished. Finally, the sense of touch, especially in the fingertips, diminishes with age as does the ability of the body to regulate heating and cooling. As a result, older people are more affected by heat waves or cold spells. Since most of these changes occur gradually, most older people adjust to them by making incremental changes in their lifestyles.

  5. What effects does aging have on the bones, joints, and muscles?
    Bone depletion is a natural part of aging that begins as young as age 30. One of the more serious consequences of bone loss is osteoporosis. Those at greatest risk of osteoporosis are small-boned postmenopausal women. New treatments for osteoporosis promise to increase bone density and improve the quality of life for older women.
    In both women and men, the most common cause of disability in later life is arthritis, a disease of the joints. Mild arthritis causes pain and discomfort; severe forms, like rheumatoid arthritis, can be crippling. The development of artificial joints has restored freedom of movement to severely arthritic persons.
    Finally, as people age, their muscles atrophy and their strength declines. Studies show that strength training and other forms of exercise can dramatically reduce the loss of muscle strength in the aged.

  6. How does aging change a person's sexual capacity?
    Menopause signals the end of a woman's fertility. The physical changes associated with menopause include hot flashes and the loss of natural vaginal lubrication. Hormone replacement therapy can relieve these menopausal symptoms, but is associated with a slightly increased risk of breast cancer.
    There is no male equivalent to menopause, although male hormone levels do decline with age. One problem some older men experience is erectile dysfunction, or impotence. While some cases of erectile dysfunction have a physical cause, more often the cause is psychological.

  7. What effects does aging have on the heart and blood vessels?
    High blood pressure, or hypertension, occurs when a person's arteries become less pliable with age or are blocked by accumulations of plaque. If the coronary artery becomes blocked, a heart attack will ensue. A number of medical procedures can reduce the risk of heart attacks. Balloon angioplasty is a technique that is used to open blocked arteries. In coronary bypass surgery, blocked arteries are replaced with blood vessels taken from other parts of the body. Finally, artificial pacemakers can be inserted in the chest to steady an irregular heartbeat.

Quadagno, Aging 4eOnline Learning Center

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