Although not a definition of aging, but the five characteristics of aging have been identified by experts. Biological theories also try to explain why people age differently over time and what factors influence longevity, resistance to organisms, and death or cellular changes. An understanding of the biological perspective can provide nurses with knowledge about the specific risk factors associated with aging and how people can be helped to minimize or avoid risks and maximize health.
1. Free Radical Theory
Free radicals are products of cellular metabolism which are highly reactive molecules. This molecule has a strong extracellular charge that can create reactions with proteins, change their shape and properties, these molecules can also react with lipids in the cell membrane, affect their permeability or can bind to cell organelles. This theory states that aging is caused by the accumulation of irreversible damage due to oxidizing compounds. Where free radicals can be formed in nature, unstable free radicals result in the oxidation of organic materials such as carbohydrates and proteins.
2. Genetic Theory
The causal theory explains that aging is mainly due to the formation of genes and the impact of the environment on the formation of the genetic code. According to genetic theory, aging is an unconsciously inherited process that goes on over time to change cell or tissue structure. In other words, changes in life span and longevity are predetermined. Genetic theory consists of deoxyribonucleic acid (DNA) theory, accuracy and error theory, somatic mutation, and glycogen theory. These theories state that the process of replication at the cellular level becomes disorganized due to inappropriate information provided from the cell nucleus. The DNA molecule crosslinks with other elements thereby changing the genetic information. The existence of these crosslinks results in errors at the cellular level which ultimately results in the system and organs of the body failing to function. Evidence supporting these theories includes the development of free radicals, collagen, and lipofuscin. In addition, the increased frequency of cancer and autoimmune diseases associated with increasing age suggests that mutations or errors occur at the molecular and cellular levels.
3. Cross Link Theory
The crosslink and connective tissue theory states that the molecules of collagen and elastin, components of connective tissue, form compounds that increase the rigidity of cells for a long time, crosslinks are thought to be the result of chemical reactions that cause animosity between molecules that normally separate or in short old or worn out cells, reactions the chemical causes less elasticity and loss of function. Examples of age-related connective tissue crosslinks include decreased tensile strength of the arterial walls, tooth loss, dry and fibrous tendons.
4. Wear and Tear Theory
This theory proposes that the accumulation of metabolic waste or nutrients can impair DNA synthesis, thereby promoting molecular and ultimately organ malfunction. Proponents of this theory believe that the body will suffer damage according to a schedule.
Free radicals are examples of metabolic waste products that cause damage when accumulation occurs. Free radicals are rapidly destroyed by protective enzyme systems under normal conditions. Some free radicals manage to escape this destructive process and accumulate in important biological structures, when organ damage occurs.
Because the metabolic rate is directly related to the formation of free radicals, scientists have hypothesized that the rate of free radical production is related to the determination of the life span. Calorie restriction and its effect on prolonging life span may be based on this theory. Calorie restriction has been shown to increase life span in rats. Throughout their lifetime, the mice had decreased incidence of functional decline, and experienced fewer age-related disease conditions, reduced functional decline, and decreased incidence of aging-related diseases.
5. Immunity Theory
The theory of immunity describes a decline in the immune system associated with aging. As people get older, their defenses against foreign organisms decrease, making them more susceptible to suffering from various diseases such as cancer and infections. As the function of the immune system decreases, there is an increase in the body's autoimmune response. As people age, they may develop autoimmune diseases such as rheumatoid arthritis and allergies to food and other environmental factors.
Proponents of this theory often focus on the role of the thymus gland. The weight and size of the thymus gland decrease with age, as does the body's ability to differentiate T cells. Due to the loss of T cell differentiation, the body mistakenly recognizes old, irregular cells as foreign and attacks them. The importance of health care, disease prevention, and health promotion approaches to health care, especially at a time of aging cannot be overlooked. Although everyone needs regular check-ups to ensure early detection and treatment as early as possible, in the elderly the failure to protect the aging immune system through these health checks can lead to early and unexpected death. In addition, national immunization programs to prevent the occurrence and spread of epidemic diseases, such as pneumonia and influenza among the elderly, also support the theoretical basis of nursing practice.
6. Neuroendocrine Theory
Previous discussions of the thymus gland and the immune system and the interactions between the nervous and endocrine systems yield remarkable similarities. In the latter case scientists have thought that aging occurs due to a slowdown in the secretion of certain hormones which have an impact on reactions regulated by the nervous system. It is more clearly demonstrated in the pituitary, thyroid, adrenal, and reproductive glands.
One of the neurological areas that is universally impaired by aging is the reaction time required to receive, process, and react to commands. Known as behavioral retardation, this response is sometimes interpreted as resistance, deafness, or lack of knowledge. In general, none of these things actually happen, but older people are often made to feel as though they are uncooperative or disobedient. Nurses can facilitate the process of providing care by slowing down instructions and waiting for their response.
7. Environmental History
According to this theory, factors in the environment (eg industrial carcinogens, sunlight, trauma and infection) can bring about changes in the aging process. Although these factors are known to accelerate aging, the impact of the environment is more of a secondary impact and not a major factor in aging.
Nurses can have in-depth knowledge of the impact of this aspect on aging by educating all age groups about the relationship between environmental factors and accelerated aging. Science is just beginning to uncover the various environmental factors that can influence aging.
Understanding the Concept of Aging