WEAR AND TEAR THEORY OF AGING EPUB

The damage or error theory include 1) Wear and tear theory. Cells and tissues have vital parts that wear out resulting in aging. Like components of an aging car, parts of the body eventually wear out from repeated use, killing them and then the body. geriatrics, health and fitness, bioscience, theories of aging, evolvability, aging theories summary Wear and Tear Aging Theories. Theories of Aging Mechanisms. “Wear and Tear” Theory. - Cells are damaged by toxins in diet and environment. - Repair processes gradually lost over time.


WEAR AND TEAR THEORY OF AGING EPUB

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WEAR AND TEAR THEORY OF AGING EPUB

WEAR AND TEAR THEORY OF AGING EPUB

There are not many age-related ureter changes in the urinary system. For the urinary wear and tear theory of aging below the bladder, however, age-related changes occur thereby causing dysuresia, pollakisuria, and urinary incontinence.

Changes in the respiratory system Based upon the qualitative deterioration in both elastic fibers and collagen fibers, lung tissues become less elastic and expansile.

Even if there are no changes in the number of alveoli, the amount of elastic fibers in the alveolar wall is decreased and the size of the alveoli is smaller with slight expansion of the alveolar ducts as well as the respiratory bronchioles. Thus, the elderly are at high risk of atelectasis and postoperative pneumonia owing to gradual reduction of arterial blood PCO2, an increment of dead space, a decrease of the expiratory volume and expiratory rate, airway cilia impairment, and defense mechanism dysfunctions.

Additionally, the respiratory muscles and the thorax are also altered by aging. Weakened respiratory muscles and a stiff diaphragm are wear and tear theory of aging from the age of This seems to be caused by aging-associated scoliokyphosis, calcification of the intercostal cartilages, and spondylarthritis.

The reduced diffusion capacity due to aging is induced from a decrease in the lung area owing to damage to the alveoli, an increase in thickness of the alveolar walls, and small-airways obstruction.

The Mechanisms of Aging Although a number of studies have been carried out regarding the causes of aging so far, it is still not possible to explain them all by a single theory.

In other words, research techniques and approaches associated with aging have been varied with the development of life sciences as well as natural sciences, but it is still left to be elucidated what causes aging.

WEAR AND TEAR THEORY OF AGING EPUB

Therefore, the authors would like to introduce several wear and tear theory of aging which have gained attentions among the published theories up to date. Genetic program theory According to the genetic program theory, aging is programmed in each species because each species has its own average longevity since they are born.

The theory is supported by the fact that the average lifespan in humans has constantly increased in the past years without big changes in the maximum lifespan of humans.

The same life curve is shown for animals and plants and in other studies, suggesting that genetic mutations result in prolonged lifespan. This theory posits that aging is the extended genetic signaling of life from the fertilized egg to the grown-up stage.

People who support this theory believe the presence of senescence genes control aging-related phenomena due to slowdown or the stoppage of biochemical metabolic pathways. These senescence genes are expressed at different time wear and tear theory of aging depending on the kinds of cells.

During the growth of organisms, a lot of cells are proliferated while many unnecessary cells are disappeared at the same time.

WEAR AND TEAR THEORY OF AGING EPUB

Similarly, as the life of unnecessary cells is controlled by the genes based on an accurate timeline, the cells in the aging processes could be managed in the same manner.

However, the theory has been rejected because animals protected from the damages also age without any alteration of their maximum lifespan, and therefore, such damages are not the factors causing aging but just time-dependent changes.

Wear and Tear Theory of Aging

When human fibroblasts are continuously sub-cultured, the lifespan of cell division is estimated to be times approximately. Therefore, the lifespan of the cells is considered to be programmed already and it has been reported which shortened telomeres at the chromosomal ends are responsible.

They are about 12 kbp length and lose telomeres when going through around times of cell division. The length is very similar to the lifespan of cells that are observed while culturing.

Telomerase which prevents against telomere shortening is expressed in immortalized cells and cancer cells with very high wear and tear theory of aging.

Modern Biological Theories of Aging

Therefore, telomere shortening takes place constantly by the enzyme so that immortalization or proliferation of cancer cells would be ongoing. Generally, endocrine hormones participate in controlling growth, metabolism, temperature, inflammation, and stress.

Since the endocrine system which takes part in the wear and tear theory of aging of life and the species plays significant roles, there are not many changes induced by aging when the hormone system for maintaining the species is greatly altered by aging. It would then interfere with the proper functioning of the tissues eventually so that the progression of aging is stimulated.

A study, reporting that albino rats, possessing a shorter lifespan than humans, urinate 10 to 15 times more of oxidatively-damaged nucleotides than humans, and the increase in damaged DNA in brains by aging also supports the hypothesis.

In addition, it has been known that the ability to repair DNA damages is directly proportional to the lifespan of species wear and tear theory of aging the repair ability is impaired in normal cells due to the progression of aging.

  • Modern Biological Theories of Aging

The theory hypothesizes that if there are any errors in any of those procedures, incorrect genes, mRNA, and proteins would be produced so that the cells would be impaired; however, more wear and tear theory of aging need to be done in this area in order to support this theory.

Even though accumulation of these errors is partially eliminated by the repair system, such a repair system would not operate perfectly and permanently because errors may be accumulated in the repair system as well.

In the case of poikilotherms such as nematodes, insects, and fish, their lifespan is generally increased as the habitat temperature is elevated while it is decreased as the temperature is lowered.



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