Free radicals are molecules that are very reactive and are responsible for aging. They can be formed in the atmosphere or in living organisms. However, Demographic aging is evident in the population pyramid. This usually presents a pronounced narrowing in the lower part, corresponding to the younger ones, in developed countries.
In fact, in Spain there are already more than 9 million people who exceed the threshold of 65 years , that is, more than 20% of the Spanish population. According to the National Institute of Statistics, it is expected that by the year 2064 that percentage will double, which will become a real problem that puts evidence the need to modify the current socio-economic system of the developed regions.
The average life expectancy in women exceeds 85 years , while that of men scarcely reaches 80. There are many theories about this difference. Presumably, the most successful is one that takes into account the different systems of life between them, as a consequence of social differences between men and women, and differences in the functioning of the endocrine system.
But what is meant by aging? From a biological perspective, Aging is a natural and complex process characterized by the progressive deterioration of organic functions. Among the physiological characteristics of aging are the following:
- Decrease in the capacity of the bladder.
- Reduction of cardiovascular health.
- Decrease in mineral bone mass.
- Decline of the immune system .
- Reduction of muscle mass.
- Accumulation of fat.
Theories of aging
There are several theories to explain this phenomenon. They can be classified Classify them into two groups:
- Evolutionary and genetic theories.
- Stochastic theories.
According to evolutionary and genetic theories, he aging It is part of a phenomenon of development and continuous maturation, controlled and genetically programmed.
The stochastic theories , on the contrary, they argue that Aging is caused by random damage to different biological molecules . These damages accumulate gradually as time passes until triggering a complete physiological decline.
Within stochastic theories, probably the most relevant is the Theory of free radicals , of which surely we have already heard. It was proposed by Harman in 1956. To fully enter into this theory, let's first clarify What are the free radicals.
They are understood by free radicals those molecules of our organism what are they presenting, in its outermost orbital, at least one unpaired electron. This characteristic confers them a huge reactive power , with which they are able to originate changes in the chemical composition of cellular structures.
On several occasions, these modifications trigger errors that lead to cell death. Definitely, Free radicals are incompatible with life. There are many types of free radicals; however, the most relevant in the aging of the human being are those derived from oxygen molecules.
Free radicals against aging
Hydrogen peroxide (H 2 OR 2 ), the superoxide radical (O 2 - ) or the hydroxyl radical (OH - ) are some examples of reactive species derived from oxygen. As you can guess, the appearance of free radicals is a direct consequence of the aerobic respiration . That is, aging affects more directly those living beings with this type of breathing.
Precisely because of this, the beings with aerobic breathing have developed a series of defense mechanisms against these reactive molecules. Enzymes such as superoxide dismutase (SOD), catalase or glutathione oxidase, present naturally in our body, accelerate the inactivation of free radicals , which prevents serious damages.
Also, in case this first barrier fails, we have a second barrier of defense constituted by what we know as to antioxidants . Now, the antioxidants are those molecules capable of slowing the damaging effect of free radicals , which reactions together with them before they can modify some important molecule for proper cell function. Uric acid, antioxidant vitamins (A, C and E) or beta carotene , are just some examples.
When there is a higher proportion of free radicals than antioxidants and neutralizing enzymes, the oxidative stress and, consequently, it gets old. Probably the most accurate theory is one that takes into account the theory of free radicals, as well as genetic and evolutionary aspects, such as the shortening of telomeres with each cell cycle.