Anatomical Effects of Aging

Bones are deceptive: From the outside, they appear hard and stagnant. But bones are bustling with activity. Their tough exterior conceals a vast network of blood vessels that transport nutrients to, and wastes away from, working bone cells. Bones are constantly being remodeled; they are in a continuous cycle of destruction and renewal until the day you die.

The problem is, as time passes you lose more bone than you make. As a result, bones thin and become increasingly susceptible to fracture. As this process accelerates after age 50, osteoporosis becomes more common. Osteoporosis is a condition of progressive bone loss that is painful, disfiguring, and debilitating.

It weakens bones to the point that fracture comes easily. Even coughing, tugging on a cabinet door, and especially a fall, can cause a fracture in those who suffer from advanced osteoporosis. Some bone loss with age is unavoidable, but the rate at which bone is lost is highly individual.

Genetics plays a role in the development of osteoporosis -- Caucasian and Asian women are more likely to develop osteoporosis, as are those who have relatives with the disease. Menopause is also a culprit: Bone loss accelerates in the five years or so after menopause.

Bad habits, such as smoking and excessive use of alcohol, also contribute to bone loss, as does a sedentary lifestyle and inadequate intake of calcium and vitamin D. Certain medications such as cortisone-like drugs and cholestyramine, a drug to lower blood cholesterol levels, also accelerate bone loss. So do some medical conditions such as rheumatoid arthritis.

However, much research proves that regularly performing weight-bearing exercise, such as walking and lifting weights, and getting an adequate amount of calcium and vitamin D can keep bones strong longer, building bone and reducing the risk of osteoporosis, even in the elderly

If you think you're getting shorter, you're probably right. Everyone shrinks with age. We're tallest by the end of our forties, then lose up to two inches in height by age 80. The loss in height is gradual but accelerates late in life. Why do we get shorter with age? There are myriad reasons including weaker muscles; water loss; postural changes; and deterioration of the spongy disks separating the vertebrae in our backbone, causing a compression of the spine.

Women tend to lose more height than men because they are more often the victims of osteoporosis, which results in loss of bone tissue in the vertebrae of the backbone, compressing it and making you shorter. That's why it's so important to maintain bone health and strength throughout life. And it doesn't hurt to sit up straight, either.

Joints become less resistant to wear and tear with time. That's in part because of the changes in cartilage, the tissue that cushions the tips of the bones in your joints. Aging causes cartilage to lose water, making it more vulnerable to injury from repetitive motion and stress. Arthritis is characterized by pain and stiffness in the joints, and in some forms, swelling, redness, and heat.

It is more common with each passing decade. Osteoarthritis, the most common form of arthritis, occurs when cartilage begins to fray and decay. Osteoarthritis is usually confined to hips, knees, spine, and hands.

Carrying around excessive weight aggravates osteoarthritis in the knees and hips, which bear weight. In fact, being overweight increases your risk of developing osteoarthritis. Regular physical activity may help reduce joint pain and stiffness and increase flexibility, muscle strength, and endurance.

You may have noticed that you can't lift heavy loads nearly as well as you could five or ten years ago. That's because aging causes a decrease in the strength, size, and endurance of muscle tissue, perhaps due in part to decreased blood flow to muscle tissue. But don't put less strength and tone down to age: Inactivity wreaks much more havoc on muscles than time does.

Sitting around accelerates muscle loss. In fact, experts say the loss in strength and stamina that we take for granted with old age is in part caused by reduced physical activity. By age 75, one in three men and half of all women get no regular exercise, which exacerbates the muscle loss that age causes.

Skin is composed of two main layers: the epidermis, the layer you wash and dry, and the dermis, which lies directly below its more visible counterpart and is where hair and sweat glands originate. Dermal and epidermal cells diminish in aging. The dermis actually thins by about 20 percent, and the blood supply to it drops off with time. Wrinkles develop, primarily due to a loss of collagen, a cementlike protein that holds cells together.

When it goes, so goes elasticity, the property that provides skin with its resilience, helping you avoid laugh lines and crow's feet in your youth. Sun exposure, too, is a major contributor to the development of wrinkles. In fact, the sun causes most skin damage, including brown "age spots" and skin cancers.

As skin gets thinner and less elastic, it becomes more fragile, bruising and tearing more easily and taking longer to heal. The loss of some sweat and oil glands from the dermis may result in chronically dry skin. Thinning skin also compromises its ability to act as a barrier to infection. Skin injuries, more common with age, also increase your vulnerability to infection.

Aesthetics aside, thinning skin has implications for your health. Your skin participates in the body's vitamin D production. Vitamin D is calcium's partner in helping keep bones strong. It gets its start in skin that's been exposed to strong ultraviolet light.

Since aging skin has a limited capacity to initiate vitamin D production, vitamin D deficiency is more common in older people, especially those living in northern climates, where the sun is too weak to make vitamin D for half the year. Applying a sunscreen with a Sun Protection Factor (SPF) of 8 or higher helps protect your skin but blocks much-needed ultraviolet rays.

In the next section, learn about the cardiovascular effects of aging and how to manage them.

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