Ageing (or aging) is the process of becoming older. It represents accumulation of changes over time. Ageing is one of the greatest risk factors for most human diseases. The causes of ageing are unknown and the process is not properly understood.
Many changes occur in the body as it grows. After maturity, age-related changes bring about gradual decline in body functions. The peak of mature physiological function is short lived. Organs such as kidneys start declining after the age of 30. In both infancy and old age body functions are less efficient. For examples, in both infants and old people, temperature regulation is less effective.
Most organs of the body mature during puberty. They are most efficient during early adulthood. The body can repair the tissues of most organs. However, the brain and myocardium are exceptions.
At maturity most organs have considerable spare capacity or functional reserve. Functional reserve is the remaining capacity of an organ to perform its physiological activity. It indicates the loss of function which must occur before physiological changes become evident. Functional reserve declines with age.
The causes of ageing are not known and the process is poorly understood. Several theories have been proposed to explain ageing. A number of factors affect the lifespan of an individual. Some of these factors are genetic. However, environmental factors, nutrition and lifestyle (smoking, drinking alcohol and lack of exercise) strongly influence lifespan.
Effects of ageing on the body
System | Physiological changes | Common consequences |
Nervous system |
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Special senses |
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Respiratory system |
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Cardiovascular system |
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Endocrine system |
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Digestive system |
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Urinary system |
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Resistance and immunity |
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Musculoskeletal system |
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Reproductive system |
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