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Aging is the process of growing older and includes changes in both biology and psychology. Biology refers to the way the body functions. Psychology describes how the mind functions. How people age has to do with genetics, environment, and lifestyle over a lifetime.

What is the information for this topic?

Experts do not fully understand why the body ages as a person gets older. The average life span in 1900 was 47 years. Now, life expectancy is age 76. This increase is due to improvements in sanitation, medical care, and the discovery of antibiotics. The increase in the number of older people is changing the makeup of society.

• genetic, which means it is influenced by the factors and conditions that are passed on from parents to offspring
• biochemical, which refers to activities in the cells, tissues, and organs of the body
• physiological, which means how the body and all of its components function together

There are two major theories on aging. People who follow the program theory think that aging is based on a biological timetable. Others who believe in the damage or error theory say that aging occurs as the environment assaults the body and causes it to age. Many people believe it is both biology and environment that causes aging. The major beliefs for each theory are listed below:

Program theory

• Genes switch on and off in turn, causing different things to happen at different times. Organ systems in each person can age at different rates.
• Hormones act as a biological clock controlling the pace of aging.
• The immune system breaks down, later leaving a person more and more prone to infection and disease.

Error theory

• Cells and tissues have vital parts that wear out.
• If a person has a high metabolic rate, his or her life span will be shorter.
• Proteins in the body build up. This slows down the body's processes, and the body begins to age.
• Oxygen radicals collect in the body and damage it. The organs eventually stop working.
• The system in the body that synthesizes proteins stops working well. Faulty proteins are developed and cause damage to cells, tissues, and organs.
• Genes mutate as the body ages, causing cells to malfunction and break down.

Experts used to believe that chronic disease and disability were always part of aging. Now it is known that much disease can be prevented or controlled. Living a healthy lifestyle can have a huge positive impact on aging and preventing disease. The three leading causes of death among people in developed nations are heart disease, stroke, and cancer. Medical experts know a great deal about how to prevent death from these causes.

Healthy lifestyle

• Stay active. Without exercise, muscle mass declines about 23% between the ages of 30 and 70. Exercise can prevent muscle mass decline.
• Maintain a healthy weight. People who are as little as 11 pounds over the healthy weight range for their height and build have more risk of disease. Eating fewer calories may work by preserving cells, moderating a decline in growth hormone, and keeping the immune system working well.
• Do not smoke and avoid being around smoke from tobacco.
• Maintain active personal relationships. People who are married or who have healthy, supportive relationships with others live longer.
• Eat five servings of fruits and vegetables each day. Follow the food guide pyramid. Fruits and vegetables have naturally occurring antioxidants that prevent free radicals from damaging cells in the body.
• Avoid getting too much sun. Frequent, long exposures to the ultraviolet light in sunshine can age the skin and increase the risk for skin cancer.
• Keep fat in the diet under 30% of total calories. Also, get the nutrients needed for a healthful diet.
• Have routine physical exams as recommended by the doctor.
• Limit stress and practice stress-reduction techniques.
• Limit alcohol intake.

These specific practices have been linked with both the prevention of diseases and a person's quality of life as he or she ages.