Basics Of Aging
Aging is an inevitable life process that occurs at a gradual and progressive rate. Everyone is familiar with the basic concept of aging, but very few are aware of the underlying biological changes that lead to aging.
Externally, aging changes the skin’s appearance making it less elastic and wrinkled, it alters the hair color, and it also leads to an increased susceptibility to diseases and declining physical strength. In this article, we shall look into the underlying physiological changes that lead to these externally apparent changes.
As people age, the organs, tissues, and cells deteriorate as the essential pathways and processes that keep our body functioning normally starts to undergo negative changes. These changes include insulin resistance, changes in body composition, and a decline in growth hormone, insulin-like growth factor, and sex steroids.
What is metabolism?
Metabolism is the sum of chemical processes that occur within each and every living organism to maintain life. It encompasses the entire process of food intake, digestion, and conversion into energy with the help of oxygen inhaled by our respiratory system. The energy is distributed throughout the body, into the skeletal muscles and the vital organs. The entire process is regulated by the precise production and circulation of hormones.
How does aging affect metabolism?
With aging, the production of these hormones declines, resulting in reduced metabolism, poor energy, and nutrient supply to cells, and subsequent deterioration of organs and their functioning ability.
The risk of developing life-threatening conditions such as type 2 diabetes, stroke, and hypertension increase exponentially with aging. A major metabolic syndrome found in most older adults is insulin resistance. Insulin resistance results in a deficiency of glucose supply to the cells. The body compensates for glucose deficiency through other sources and processes such as hepatic gluconeogenesis, adipose lipogenesis, defective glycogen synthesis, and glucose uptake.
With aging and disruption of normal metabolism, normal body fat composition and storage also become altered. This leads to increased abdominal obesity. Abdominal obesity is more dangerous than limb obesity as many vital organs lie underneath the abdomen.
Proinflammatory cytokines released by aging cells or immune cells can also interfere with insulin production and increase the number of senescent cells. Adiponectin is another metabolic regulator that is derived from adipose tissue and is associated with aging. This hormone is increased in lean individuals or those following calorie-restricted diets. An increase in adiponectin has also been observed in centenarians and long-lived mouse mutants.
Aging is a complex process, still under study. Many theories exist which try to explain the physiology behind aging. Mitochondrial dysfunction is one of the major widely renowned theories. According to it, mitochondrial dysfunction releases reactive oxygen species (ROS), which can cause oxidative damage to macromolecules.
There are also some studies to back this theory. The studies found mice with mitochondrial dysfunction to undergo accelerated aging, impaired mitochondrial function, and sarcopenia.
Study findings also found a significant correlation between insulin resistance, glucose tolerance, and mitochondrial activity. The theory is still under research, and more extensive studies are required to prove its validity.