aging

aging,

in biology, cumulative changes in an organism, organ, tissue, or cell leading to a decrease in functional capacity. In humans, aging is associated with degenerative changes in the skin, bones, heart, blood vessels, lungs, nerves, and other organs and tissues. The branch of medicine that deals with the disorders of aging in humans is geriatricsgeriatrics
, the branch of medicine concerned with conditions and diseases of the aged. Many disabilities in old age are caused by or related to the deterioration of the circulatory system (see arteriosclerosis), e.g.
..... Click the link for more information. .

Biologists have advanced a variety of theories to explain aging, but most of them agree that this process is largely determined by genes. This view is suggested by the great range of lifespans among different animal species—from a few days in the fruit fly to more than 100 years in some tortoises. Scientists have recently learned how to double the lifespans of such laboratory organisms as roundworms and fruit flies through genetic manipulation, and mutant genes in mice have been observed to have a comparable effect in postponing aging.

At the cellular level, an important recent finding has been that the lifespans of cells in the human body are determined by strings of DNA (genetic material) called telomeres, which are located at the ends of the chromosomes. Each time a cell divides, the telomere becomes shorter; the senescence and death of the cell is triggered when the telomere is reduced to a certain critical length. Telomerase, an enzyme that can intervene in this process, is being closely studied in relation to cancer as well as aging.

Environmental factors have been observed to affect aging as well. Scientists have discovered that they can significantly postpone aging in mice by providing them with very low-calorie diets, and recent studies of rhesus monkeys on low-calorie diets appear to be having the same results. It is believed that these diets slow the aging process by lowering the rate at which tissue-damaging substances called free radicals are produced in the body. One aim of these studies is the development of antioxidantantioxidant,
substance that prevents or slows the breakdown of another substance by oxygen. Synthetic and natural antioxidants are used to slow the deterioration of gasoline and rubber, and such antioxidants as vitamin C (ascorbic acid), butylated hydroxytoluene (BHT), and
..... Click the link for more information. drugs that could slow the aging process in humans by protecting against free radicals. The use of testosterone, melatonin, human growth hormone, and other hormones as "anti-aging" treatments is medically unproven and potentially dangerous, as the hormones can have damaging side effects.

Bibliography

See L. Hayflick, How and Why We Age (1994); J. Silvertown, The Long and the Short of It: The Science of Life Span and Aging (2013); publications of the National Institute on Aging.

Aging

the gradual changes that occur in the course of the development of an organism, which begin long before old age and result in the progressive weakening of an organism’s adaptive capacity. Aging is the final stage of ontogeny. It is studied in gerontology. The rate of aging determines the life-span of different animal species, which is genetically determined, and the relationship between the metabolic, structural, and functional manifestations arising in the various systems of an organism.

The development of ideas on the nature of aging is closely associated with the conflict between various philosophic schools over the origin of life, the evolution of the animal world, and the relationship between life and death in individual development. F. Engels defined the relationship between the categories of life and death as follows: “Life is always thought of in terms of its inevitable result, already fixed in the embryo—death.” Aging is an inherent part of individual development during which phenomena may arise that are similar to the early stages of ontogeny but have a different mechanism.

There is no generally accepted explanation of the mechanisms of aging. More than 300 hypotheses have been advanced, many of which are of purely historical interest. Most of the modern hypotheses can be divided into large groups. According to the first group, aging is a programmed process of quantitative and qualitative changes that naturally occur in the genetic apparatus, which is controlled by genes, as are all the other stages of an organism’s development. According to the second group, aging is a result of a disturbance or an injury to the genetic apparatus in the course of vital activities—an accumulation of “errors” caused by many factors, including cross linkages, free radicals, and cellular metabolic products. A compromise view also exists, which holds that initial genetically programmed changes create “vulnerable” places which undergo the injurious effects of metabolites accumulated in the course of vital activities.

Aging hypotheses greatly emphasize the exogenous and endogenous factors that contribute to the development of aging. Some hypotheses attempt to elucidate the sequence of changes that occur with aging. The American scientist H. Curtis, the British scientist C. Minot, and the Soviet scientist I. I. Shmal’gauzen have stated that postmitotic, highly differentiated cells are responsible for initial aging mechanisms. According to L. Hayflick, mitotically active cells have a limited potential for division, which also results in the initial aging of an organism.

The aging process has been studied primarily in vertebrates, including man. Some investigators believe that aging starts with the fertilization of a cell, after the cell’s first division (the Soviet scientist M. S. Mil’man) or after the cessation of growth (G. Bidder). Others believe that aging occurs during all age periods (the Soviet scientists A. V. Nagornyi, V. I. Nikitin, I. N. Bu-lankin) or develops in the climacteric period (I. V. Davydovskii). Cells differ in their capacity for division, in the length of their life-span, and in the period of the commencement of their aging. The extremely close interrelationships and interdependence between age-related changes at different levels of the organization of living organisms and different levels of vital processes determine both the onset of aging after an organism’s conception and the course of aging in the later stages of ontogeny.

Many years ago, S. P. Botkin and E. Metchnikoff substantiated the need to distinguish between physiological (natural) and premature (pathological) aging. In the opinion of many investigators, premature aging results from unfavorable environmental factors and from disease. Significant changes in the aging process develop at the cellular level and are manifested by decreased cellular excitability and lability, by increased duration of the action potential, and by changes in synaptic conduction. With aging, cells and tissues are less affected by nerves and become more sensitive to some humoral factors because of changes in the metabolism of mediators. Characteristically, the level of internal respiration drops because of a decrease in the number of active cellular elements and mitochondria contained in these elements and a decrease in the oxidative capacity of the mitochondria. The increase in the rate of glycolysis cannot compensate for the insufficient production of energy by oxidation-reduction processes, causing a decrease in the concentration and rate of renewal of high-energy compounds. The reactivity of active protein groups changes, thus causing an accumulation of inert protein molecules within the cells.

With aging, changes also occur in different systems, including the nervous system. Internal inhibition is affected sooner than other processes. The subordinating influence of the higher parts of the central nervous system on the lower parts weakens, the lability of nerve centers decreases and their sensitivity to some humoral factors increases, and the relationships between the centers and the periphery change. Neurodynamic shifts underlie the changes that occur in the mind and the behavior of the elderly, whose ability to work and concentrate declines and who are apt to become emotionally unstable. Arterial pressure often increases, the heart beat slows, and cardiac output decreases. Peripheral resistance increases, and vascular walls become less elastic. Pulmonary ventilation and the vital capacity of the lungs decrease. Age-related changes in hemodynamics and respiration become very apparent during strenuous activity, for example, physical work. The enzyme activity of digestive juices and the rate of absorption of fatty acids, amino acids, and glucose decrease, and gastrointestinal motility and the antitoxic function of the liver weaken.

According to the adaptation-regulation theory of V. V. Frol’-kis, aging is inherently contradictory: while some processes weaken, others strengthen as a result of the mobilization of important adaptive mechanisms. The mechanisms include an increase in the number of nuclei in many cells following a change in the activity of the genetic apparatus of each nucleus, an intensification of glycolysis at the same time that the rate of internal respiration decreases, the hypertrophy of some cells and atrophy of others, and an increase in tissue sensitivity to many hormones following a weakening of endocrine function.

Changes in the neurohumoral regulation of functions and vascular permeability play a major role in the aging of a complex organism and in the development of the organism’s adaptive mechanisms (I. P. Pavlov, A. A. Bogomolets, N. B. Man’kovskii). With aging, metabolic and functional parameters do not change smoothly, gradually, and in the same direction. Some parameters, for example, myocardial contractility, the functioning of the digestive, thyroid, and sexual glands, and visual and acoustic acuity, progressively deteriorate with age, whereas other parameters, including blood-sugar levels, cellular membrane potentials, and some parameters of blood morphology, do not change significantly. There is an intensification of still other parameters, including the synthesis of some hypophyseal hormones, the sensitivity of many cells to humoral factors, and the activity of some enzymes.

The irregularity of aging is related to the fact that changes in organs and tissue develop differently in different age periods (especially in the climacteric period). For example, the thymus is active in childhood, the sexual glands of women become less active by the age 50, and some hypophyseal functions are preserved even in advanced old age. Age-related changes steadily intensify, limiting the adaptability of the body and promoting the development of many diseases, which become more frequent with old age. The proper balance of work and rest and a nutritious, well-balanced diet are important factors in delaying the effects of aging.

REFERENCES

Marx, K., and F. Engels. Soch., 2nd ed., vol. 20, p. 610.
Nagornyi, A. V., V. N. Nikitin, and I. N. Bulankin. Problema stareniia i dolgoletiia. Moscow, 1963.
Davydovskii, I. V. Gerontologiia. Moscow, 1966.
Berdyshev, G. D. Ekologo-geneticheskie faktory stareniia i dolgoletiia. Leningrad, 1968.
Dil’man, V. M. Starenie, klimaks i rak. Leningrad, 1968.
Frol’kis, V. V. Regulirovanie, prisposoblenie i starenie. Leningrad, 1970.
Frol’kis, V. V. Starenie i biologicheskie vozmozhnosti organizma. Moscow, 1975.
Man’kovskii, N. B., and A. Ia. Mints. Starenie i nervnaia sistema. Kiev, 1972.V. V. FROLKISIn plants. Aging in plants is very similar to aging in man and animals. Degenerative processes characteristically predominate over those that are regenerative. Aging is accompanied by structural changes in plant organs and by the gradual disintegration of all cellular organelles, including chloroplasts, mitochondria, ribo-somes, endoplasmic retícula, and dictyosomes. There is a decrease in the rate of such basic functions as photosynthesis and the synthesis of protein, nucleic acids, and other biologically important compounds. The activity of most enzymes decreases, although that of proteolytic enzymes may increase. Various environmental factors, including nutrients, light, temperature, pathogenic bacteria, and fungi, may accelerate or delay aging. Phytohormones are particularly important in the regulation of aging. For example, cytokinins may produce a secondary rejuvenation of organs. Aging may be accelerated with abscisic acid, a natural growth inhibitor.
Unlike aging in animals and man, aging in plants is accompanied by the formation of new organs, a process that frequently continues throughout the life of a plant. In some plants, all organs age and die simultaneously. For example, the agave dies after flowering. In others, for example, trees in the Central Zone, there is a cyclical, seasonal dying off of leaves at the same time that other organs remain viable. The aging of the lower leaves of many herbaceous plants is accompanied by the formation of young apical leaves.
Many practical methods used in agriculture, including the breeding of early-ripening varieties according to morphological characteristics and the rejuvenation of fruit trees and shrubs by deep pruning, are based on N. P. Krenke’s theory of cyclical aging and rejuvenation.

REFERENCES

Krenke, N. P. Teoriia tsiklicheskogo stareniia i omolozheniia rastenii. . . . Moscow, 1940.
Biologiia razvitiia rastenii. Moscow, 1975.

N. L. KLIACHKO

aging

[′āj·iŋ] (acoustics) The process by which the pressure disturbance from a passing aircraft is distorted as it propagates away from the aircraft, causing the signature to stretch out in duration and length, lose detail, and form shock waves. (biology) Growing older. (chemistry) All irreversible structural changes that occur in a precipitate after it has formed. (electricity) Allowing a permanent magnet, capacitor, meter, or other device to remain in storage for a period of time, sometimes with a voltage applied, until the characteristics of the device become essentially constant. (electromagnetism) Change in the magnetic properties of iron with passage of time, for example, increase in the hysteresis. (engineering) The changing of the characteristics of a device due to its use. Operation of a product before shipment to stabilize characteristics or detect early failures. (materials) Change in the properties of any substance with time. Change occurring in powders or slips with the passage of time. Curing of ceramic materials, such as clays and glazes, by a definite period of time under controlled storage conditions. (metallurgy) Change in properties of an alloy or metal which generally proceeds slowly at room temperatures and faster at elevated temperatures. Strain relief, occurring through long storage outdoors under varying temperatures, of iron castings intended for use as toolroom plates or lathe-bed supports. A second heat treatment of an alloy at a lower temperature, causing precipitation of the unstable phase and increasing hardness, strength, and electrical conductivity. (nucleonics) The slowing down of neutrons.

aging, Brit. ageing

1. The progressive change in a chemical and physical material with increased age; in natural rubber and synthetic elastomers, usually marked by a deterioration caused by oxidation. Also see accelerated aging, age hardening, age softening.2. The storing of varnish to improve clarity and gloss.

ageing

, aging the change of properties that occurs in some metals after heat treatment or cold working

Aging

(dreams)Dreaming about old people or your own aging may have several different meanings. An old man may symbolize wisdom and forgiveness while an old woman may represent life and death. In general, aging may represent the wisdom that a person acquires through experience. The dream may also be giving you a message in regard to life’s lessons. This may be a good time for you to apply some of your experience and knowledge to a current situation. This dream may also be a reflection of your concerns about aging. If you are thinking about your mortality and do not welcome maturing and age, the dream may be bringing out some of your worries and/or vanities.

aging

Aging

Definition

Starting at what is commonly called middle age, operations of the human body begin to be more vulnerable to daily wear and tear; there is a general decline in physical, and possibly mental, functioning. In the Western countries, the length of life is often into the 70s. The upward limit of the life span, however, can be as high as 120 years. During the latter half of life, an individual is more prone to have problems with the various functions of the body and to develop any number of chronic or fatal diseases. The cardiovascular, digestive, excretory, nervous, reproductive and urinary systems are particularly affected. The most common diseases of aging include Alzheimer's, arthritis, cancer, diabetes, depression, and heart disease.

Description

Human beings reach a peak of growth and development around the time of their mid 20s. Aging is the normal transition time after that flurry of activity. Although there are quite a few age-related changes that tax the body, disability is not necessarily a part of aging. Health and lifestyle factors together with the genetic makeup of the individual, and determines the response to these changes. Body functions that are most often affected by age include:

Hearing, which declines especially in relation to the highest pitched tones.
The proportion of fat to muscle, which may increase by as much as 30%. Typically, the total padding of body fat directly under the skin thins out and accumulates around the stomach. The ability to excrete fats is impaired, and therefore the storage of fats increases, including cholesterol and fat-soluble nutrients.
The amount of water in the body decreases, which therefore decreases the absorption of water-soluble nutrients. Also, there is less saliva and other lubricating fluids.
The liver and the kidneys cannot function as efficiently, thus affecting the elimination of wastes.
A decrease in the ease of digestion, with a decrease in stomach acid production.
A loss of muscle strength and coordination, with an accompanying loss of mobility, agility, and flexibility.
A decline in sexual hormones and sexual functioning.
A decrease in the sensations of taste and smell.
Changes in the cardiovascular and respiratory systems, leading to decreased oxygen and nutrients throughout the body.
Decreased functioning of the nervous system so that nerve impulses are not transmitted as efficiently, reflexes are not as sharp, and memory and learning are diminished.
A decrease in bone strength and density.
Hormone levels, which gradually decline. The thyroid and sexual hormones are particularly affected.
Declining visual abilities. Age-related changes may lead to diseases such as macular degeneration.
A compromised ability to produce vitamin D from sunlight.
A reduction in protein formation leading to shrinkage in muscle mass and decreased bone formation, possibly leading to osteoporosis.

Causes and symptoms

There are several theories as to why the aging body loses functioning. It may be that several factors work together or that one particular factor is at work more than others in a given individual.

Programmed senescence, or aging clock, theory. The aging of the cells of each individual is programmed into the genes, and there is a preset number of possible rejuvenations in the life of a given cell. When cells die at a rate faster than they are replaced, organs do not function properly, and they are soon unable to maintain the functions necessary for life.
Genetic theory. Human cells maintain their own seed of destruction at the level of the chromosomes.
Connective tissue, or cross-linking theory. Changes in the make-up of the connective tissue alter the stability of body structures, causing a loss of elasticity and functioning, and leading to symptoms of aging.
Free-radical theory. The most commonly held theory of aging, it is based on the fact that ongoing chemical reactions of the cells produce free radicals. In the presence of oxygen, these free radicals cause the cells of the body to break down. As time goes on, more cells die or lose the ability to function, and the body soon ceases to function as a whole.
Immunological theory. There are changes in the immune system as it begins to wear out, and the body is more prone to infections and tissue damage, which may finally cause death. Also, as the system breaks down, the body is more apt to have autoimmune reactions, in which the body's own cells are mistaken for foreign material and are destroyed or damaged by the immune system.

Diagnosis

Many problems can arise due to age-related changes in the body. Although there is no one test to be given, a thorough physical exam and a basic blood screening and blood chemistry panel can point to areas in need of further attention. When older people become ill, the first signs of disease are often nonspecific. Further exams should be conducted if any of the following occur:

diminished or lack of desire for food
increasing confusion
failure to thrive
urinary incontinence
dizziness
weight loss
falling

Treatment

For the most part, doctors prescribe medications to control the symptoms and diseases of aging. In the United States, about two-thirds of people 65 and over take medications for various complaints. More women than men use these medications. The most common drugs used by the elderly are painkillers, diuretics or water pills, sedatives, cardiac drugs, antibiotics, and mental health drugs.Estrogen replacement therapy (ERT) is commonly prescribed to postmenopausal women for symptoms of aging. It is often used in conjunction with progesterone. ERT functions to help keep bones strong, reduce risk of heart disease, restore vaginal lubrication, and to improve skin elasticity. Evidence suggests that it may also help maintain mental functions.

Expected results

Aging is unavoidable, but major physical impairment is not. People can lead a healthy, disability-free life well through their later years. A well established support system of family, friends, and health care providers, together with focus on good nutrition and lifestyle habits and good stress management, can prevent disease and lessen the impact of chronic conditions.

Key terms

Alzheimer's disease — A condition causing a decline in brain function that interferes with the ability to reason and to perform daily activities.Antioxidants — Substances that reduce the damage of the highly reactive free radicals that are the byproducts of the cells.Senescence — Aging.Vata — One of the three main constitutional types found under Ayurvedic principles. Keeping one's particular constitution in balance is considered important in maintaining health.

Alternative treatment

Nutritional supplements

Consumption of a high-quality multivitamin is recommended. Common nutritional deficiencies connected with aging include B vitamins, vitamins A and C, folic acid, calcium, magnesium, zinc, iron, chromium, and trace minerals. Since stomach acids may be decreased, it is suggested that the use of a powdered multivitamin formula in gelatin capsules be used, as this form is the easiest to digest. Such formulas may also contain enzymes for further help with digestion.Antioxidants can help to neutralize damage by the free radical actions thought to contribute to problems of aging. They are also helpful in preventing and treating cancer and in treating cataracts and glaucoma. Supplements that serve as antioxidants include:

Vitamin E, 400-1,000 IUs daily. Protects cell membranes against damage. It shows promise in prevention against heart disease, and Alzheimer's and Parkinson's diseases.
Selenium, 50 mg taken twice daily. Research suggests that selenium may play a role in reducing the risk of cancer.
Beta-carotene, 25,000-40,000 IUs daily. May help in treating cancer, colds and flu, arthritis, and immune support.
Vitamin C, 1,000-2,000 mg per day. It may cause diarrhea in large doses. If this occurs, however, all that is needed is a decrease in the dosage.

Other supplements that are helpful in treating agerelated problems including:

B₁₂/B-complex vitamins, studies show that B12 may help reduce mental symptoms, such as confusion, memory loss, and depression.
Coenzyme Q10 may be helpful in treating heart disease, as up to three-quarters cardiac patients have been found to be lacking in this heart enzyme.

Hormones

The following hormone supplements may be taken to prevent or to treat various age-related problems. However, caution should be taken before beginning treatment, and the patient should consult his or her health care professional.DHEA improves brain functioning and serves as a building block for many other important hormones in the body. It may be helpful in restoring declining hormone levels and in building up muscle mass, strengthening the bones, and maintaining a healthy heart.Melatonin may be helpful for insomnia. It has also been used to help fight viruses and bacterial infections, reduce the risk of heart disease, improve sexual functioning, and to protect against cancer.Human growth hormone (hGH) has been shown to regulate blood sugar levels and to stimulate bone, cartilage, and muscle growth while reducing fat.

Herbs

Garlic (Allium sativa) is helpful in preventing heart disease, as well as improving the tone and texture of skin. Garlic stimulates liver and digestive system functions, and also helps in dealing with heart disease and high blood pressure.Siberian ginseng (Eleutherococcus senticosus) supports the adrenal glands and immune functions. It is believed to be helpful in treating problems related to stress. Siberian ginseng also increases mental and physical performance, and may be useful in treating memory loss, chronic fatigue, and immune dysfunction.Proanthocyanidins, or PCO, are Pycnogenol, derived from grape seeds and skin, and from pine tree bark, and may help in the prevention of cancer and poor vision.In Ayurvedic medicine, aging is described as a process of increased vata, in which there is a tendency to become thinner, drier, more nervous, more restless, and more fearful, while having a loss of appetite as well as sleep. Bananas, almonds, avocados, and coconuts are some of the foods used in correcting such conditions. One of the main herbs used for such conditions is gotu kola (Centella asiatica), which is used to revitalize the nervous system and brain cells and to fortify the immune system. Gotu kola is also used to treat memory loss, anxiety, and insomnia.In Chinese medicine, most symptoms of aging are regarded as symptoms of a yin deficiency. Moistening foods such as millet, barley soup, tofu, mung beans, wheat germ, spirulina, potatoes, black sesame seeds, walnuts, and flax seeds are recommended. Jing tonics may also be used. These include deer antler, dodder seeds, processed rehmannia, longevity soup, mussels, and chicken.

Prevention

Preventive health practices such as healthy diet, daily exercise, stress management, and control of lifestyle habits such as smoking and drinking, can lengthen the life span and improve the quality of life as people age. Exercise can improve the appetite, the health of the bones, the emotional and mental outlook, and the digestion and circulation.Drinking plenty of fluids aids in maintaining healthy skin, good digestion, and proper elimination of wastes. Up to eight glasses of water should be consumed daily, along with plenty of herbal teas, diluted fruit and vegetable juices, and fresh fruits and vegetables with high water content.Because of a decrease in the sense of taste, older people often increase their intake of salt, which can contribute to high blood pressure and nutrient loss. Use of sugar is also increased. Seaweeds and small amounts of honey can be used as replacements.Alcohol, nicotine, and caffeine all have potential damaging effects, and should be limited or completely eliminated from consumption.A diet high in fiber and low in fat is recommended. Processed foods should be replaced by complex carbohydrates, such as whole grains. If chewing becomes a problem, there should be an increased intake of protein drinks, freshly juiced fruits and vegetables, and creamed cereals.

Resources

Other

"Anti-Aging-Nutritional Program." December 28, 2000. http://www.healthy.net/hwlibrarybooks/haas/perform/antiagin.htm."Effects of Hormone in the Body." December 28, 2000. 〈http://www.anti-aging.org/Effects_hGH.html〉."The Elderly-Nutritional Programs." December 28, 2000. http://www.healthy.net/hwlibrarybooks/haas/lifestage/elderly.htm."Evaluating the Elderly Patient: the Case for Assessment Technology." December 28, 2000. 〈http://text.nlm.nih.gov/nih/ta/www/01.html〉."Herbal Phytotherapy and the Elderly." December 28, 2000. http://www.healthy.net/hwlibrarybooks/hoffman/elders/elders.htm."Pharmacokinetics." Merck & Co., Inc. (1995–2000). December 28, 2000. http://www.merck.com/pubs/mmanual/section22/chapter304/304a.htm."To a Long and Healthy Life." December 28, 2000. http://www.healthy.net/hwlibraryarticles/aesoph/longandhealthy.htm.

aging

[āj´ing] the gradual changes in the structure of any organism that occur with the passage of time, that do not result from disease or other gross accidents, and that eventually lead to the increased probability of death as the individual grows older. See also aged and senescence" >senescence, and see the Atlas on Aging.

ag·ing

(ā'jing), [MIM*502000] 1. The process of growing old, especially by failure of replacement of cells in sufficient number to maintain full functional capacity; particularly affects cells (for example, neurons) incapable of mitotic division. 2. The gradual deterioration of a mature organism resulting from time-dependent, irreversible changes in structure that are intrinsic to the particular species, and eventually lead to decreased ability to cope with the stresses of the environment, thereby increasing the probability of death. 3. In the cardiovascular system, the progressive replacement of functional cell types by fibrous connective tissue. 4. A demographic term, meaning an increase over time in the proportion of older people in the population.

aging

(ā′jĭng)n. The process of growing old or maturing.

Ageing

Dermatology Changes in the skin and subcutaneous tissues associated with growing older. Ageing effects (e.g., patchy hyperpigmentation, fine wrinkles, telangiectasias) result from intrinsic and extrinsic processes and reflect the physicaleffects of the passage of time. Ageing skin is usually associated with a sagging face, in which deeper tissues (i.e., subjacent soft tissue) and structural landmarks lose their resiliency.
Geriatrics A multifaceted process in which bodily structures and functions undergo a negative deviation from the optimum. Ageing phenomena include decreases in memory, muscle strength, muscle mass, manual dexterity, cardiac output, and auditory and visual acuity, as well as loss or thinning of hair. Other ageing phenomena include increased body fat, and increased risk of cancer, diabetes, infections, osteoarthritis, and osteoporosis accompanied by a decrease in height due to decreased intervertebral space.
Intrinsic ageing The immutable effects of chronologic ageing, e.g., atrophy-attenuation of epidermis, retraction of rete pegs, decreased number of Langerhans’ cells and melanocytes, general decay of structural dermal and epidermal components
Extrinsic ageing Effects of external factors, e.g., sunlight, smoking, gravity and gravidity, keratinocytic dysplasia, solar elastosis, and possibly carcinogenesis; intrinsic & extrinsic ageing are intimately linked and thus not divided
Ageing phenomena
Inevitable & immutable Cataracts, decreased skin elasticity, farsightedness, fibrous replacement of muscle, greying, poor recall, slowed intestinal transit, prostatic hypertrophy, wrinkling
Inevitable but modifiable Baldness, cancer, reduced cardiac reserve, slow erection and ejaculation, decreased hearing, immunity, and vision, increased weight, liver spots (age spots), osteoporosis, decreased short-term memory, decreased stamina

aging

A multifaceted process in which bodily structures and functions undergo a negative deviation from the optimum; aging phenomena include ↓ memory, muscle strength and mass, manual dexterity, cardiac output, auditory and visual acuity, loss or thinning of hair, ↑ body fat, ↑ risk of CA, DM, infections, osteoarthritis, osteoporosis accompanied by ↓ in height due to ↓ intervertebral space. See Geriatrics, Life-extending diet Dermatology Changes in the skin and subcutaneous tissues of those whose future is shorter than their past; aging effects result from intrinsic and extrinsic processes See Aging, Aging skin, Sagging face.

ag·ing

(ājing) 1. The process of growing old, especially by failure of replacement of cells in sufficient number to maintain full functional capacity; particularly affects cells (e.g., neurons) incapable of mitotic division. 2. The gradual deterioration of a mature organism resulting from time-dependent, irreversible changes in structure. 3. In the cardiovascular system, the progressive replacement of functional cell types by fibrous connective tissue. 4. demography An increase over time in the proportion of older people in the population. 5. The process, analogous to the setting of glue, by which the bond between a nerve agent and acetylcholinesterase becomes refractory to disruption by an oxime antidote.

ag·ing

(ājing) [MIM*502000] The process of growing old, especially by failure of replacement of cells in sufficient number to maintain full functional capacity; particularly affects cells (e.g., neurons) incapable of mitotic division.

Patient discussion about aging

Q. I would like to know the best age for pregnancy? Hi I am Deontae; I got married before 1 year. I and my wife planned to have a baby after 3 years. But now she is 25. I would like to know the best age for pregnancy? Which will help us to change our plan?A. actually there is no best age for pregnancy (as far as i know), but some studies and research had shown that after 35 years old, a pregnancy is categorized as high risk, because there are some abnormalities and labor complication that are tend to happened (statistically) along with the increase of mother's age (such as: down syndrome, genetic disorder, post-partum bleeding, miscarriage, etc.)
so if your wife is now 25, i think you guys still have another 5-10 years to "accomplish" your family plan, hehehe...
Good luck, and stay healthy always..

Q. when is the most common age to get any kind of cancer? is there is such age? A. no, not really. but i guess the older you get the older something can pop out. the cells are dividing and multiplying all of our life, and cancer can occur because of mutation happened in the cells.

Q. Does eyesight always decrease with age? I am 45 years old and never had glasses. All my friends are starting to wear reading glasses. Should I expect this too?A. This is what usually happens; your eyesight deteriorates as you get older. Here is a link to a few things you can do in order to protect your eyesight:
http://www.nia.nih.gov/HealthInformation/Publications/eyes.htm

More discussions about aging

aging

ag·ing

aging

age out

age in place

aging in place

age out (of something)

age out

aging

aging,

Bibliography

Aging

REFERENCES

REFERENCES

aging

aging, Brit. ageing

ageing

Aging

aging

Aging

Definition

Description

Causes and symptoms

Diagnosis

Treatment

Expected results

Key terms

Alternative treatment

Nutritional supplements

Hormones

Herbs

Prevention

Resources

Other

aging

ag·ing

aging

Ageing

aging

ag·ing

ag·ing

Patient discussion about aging

aging

Aging

aging

aging

Synonyms for aging

noun acquiring desirable qualities by being left undisturbed for some time

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noun the organic process of growing older and showing the effects of increasing age

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adj growing old

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