The Biology of Cellular Ageing

“Wrinkles means you laughed,grey hair means you cared and scars means you lived..”

Cells are the microscopic components that make up organisms that work together to perform the processes that sustain life. Living tissue is made up of cells.

There are many different types of cells, but all of them have the same basic structure. Tissues are layers of similar cells that perform a specific function.

The collection of chemical reactions in our body is usually referred to as your metabolism. This process is the sum of all chemical changes that take place within the cells in our body.

What is Ageing?

Aging refers to the group of developmental changes that occur in the later years. Biological aging refers to age associated changes that involve the physical structures and functioning of the body and affects a person’s ability to maintain homeostasis.

To a practicing therapist, a true understanding of the aging process is essential to fully understand how illness or chronic disease compounds an already compromised system.

It is an exciting time to consider the multi factorial nature of aging, the new biological discoveries being made, and how to translate these insights to human health as longevity reaches unprecedented levels worldwide.

Theories of aging:

General theories of aging have been proposed to explain the cellular changes with aging.

There are several theories of aging and these theories fall into various categories.

1.The Stochastic Model (Accumulation of Damage to Information Molecules)

suggests that damage to cells and molecules underline aging. DNA damage and damage to proteins from a variety of sources with emphasis on free radicals and glycation combine to produce manifestation of aging. Specifically, the accumulation of damage to the information molecules proposes aging as a consequence of progressive accumulation of errors in the makeup of the cells because the cell processes do not keep up. The consequence of this error build-up is that the genetic foundation of the cell becomes altered and the expression of the essential functional protein is either limited or cannot proceed at all. DNA damage is reflected in changes in the membrane and enzymes that are made by the cell. Manifestations of the DNA damage are seen by cell membrane changes in its transport of ions and nutrients. With DNA damage, membrane bound organelles, such as mitochondria and lysosomes, are present in reduced numbers. These organelles are less effective due to the changes in their membranes and in the enzymes that regulate their function.

2. Free- Radical Theory

states that the oxidation of the protein, fats and carbohydrates results in free radical formation which interact with the key cellular constituents including proteins, DNA and lipids to generate long lived dysfunctional molecules that interfere with the cellular function. Perhaps the vulnerable structure damaged by the free radicals is the plasma membrane, which is essential for homeostasis.These free radicals are positively charged ions which can be neutralized with free circulating electrons.

3. Nonenzymatic glycosylation

can create modified forms of proteins and perhaps other macromolecules that accumulate and cause dysfunction in aging.

Recent studies suggest that cellular senescence might be a cellular model of organismal aging. This can be well explained through telomere shortening theory, telomere is the terminal end of the chromosome which does not get replicated and shortens. It is proposed that the telomere shortening is the signal that results in the shift to a senescent pattern of gene expression and that causes aging.

In conclusion, all of this affects the normal functioning of the body systems. It is evident that the aging process is multi factorial in origin. Further, it appears that in the absence of disease, the ability of an individual to maintain homeostasis through good nutrition, exercise and appropriate health care is the key to longevity and quality of life.

We are likely to make the most exciting discoveries about new avenues for therapeutic intervention at the intersection of these pathways.

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Reference- Cellular Metabolism and Aging