What is aging? Theories of aging.


How and why do people get old?
What is aging?

Everything that lives undergoes a series of physiologic changes that we call aging. In basic terms, aging is a progressive breakdown of cellular and tissue structure3s. When the process reaches a stage beyond which cells can no longer function, life ends. Presumably, each of use would like to live a full life, free of diseases...

Theories of aging have abounded in the last few decades. An early hypothesis posited that our cells are programmed for a set number of divisions, and once we reach that limit, we will die...

Research scientists have also theorized that aging may be due to the introduction of small errors in DNA during cell reproduction. With time, according to this theory, errors accumulate, leading to fatal errors in the genes after a certain number of cell divisions. The problem with this theory is that some cells which are most vulnerable to the aging process, such as neurons in the brain, do not divide at all.

The neuroendocrine theory of aging proposed that eventual failure of the endocrine system leads to gradual systemic failure of the body. Basically, the theory states that the hypothalamus and pituitary--control centers for much of the endocrine system--begin to fail, leading to disruptions in the immunity, metabolism, and other physiological functions...

Recent studies have helped to clarify the mechanics of again. Our best evidence right now points to two closely related processes, telomere shortening and free-radical damage, that play a central role in again.

The Free-Radical Theory of Aging

Free radicals attack all proteins within a cell. Proteins perform three major functions. They provide structural support, create molecular signals, and provide numerous enzymes for initiating reactions from energy production to the creation of other molecules. Each type of protein has special three-dimensional shape that is critical to its function, and even slight alteration can have deleterious effects on performance.

With age, an increasing number of these free-radical-altered proteins, called protein carbonyl products, accumulated in the body. The number of these altered proteins increases dramatically in neurodegenerative diseases, diabetes, and autoimmune diseases (such as lupus and rheumatoid arthritis). While the amount of protein carbonyl products in extremely old people who do not have one of these diseases is substantially lower than in someone with, for example, Alzheimer's disease, these proteins do significantly affect how cells and hence bodies--function past a certain age.

The third cellular component affected by accumulated free-radical damage is DNA. Remember that mitochondria have their own DNA, allowing them to reproduce themselves based on energy demands. Therefore, weigh lifters and exercise enthusiasts have a far greater number of muscle mitochondria than couch potatoes. Likewise, those who exercise their minds possess more mitochondria in their brain neurons than people who sit and watch sitcoms all day.

Health and Nutrition Secrets (that can save your life), Dr Russell L. Blaylock, MD

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