Senescence is the characteristic of that or that senescent . East adjective , which comes from the Latin word senescens, refers to who starts get older . For example: "It hurts to notice the senescence of Uncle Juan", "Scientists investigate the senescence of cells to try to find a cure for this disease", "The authorities do nothing to reverse the senescence of the people".
In its broadest sense, senescence is a irreversible change that occurs in a system or in a structure from the passage of time. The analysis of these modifications, in general, allows us to estimate the time between two specific moments.
Senescence is associated with a deterioration : Over the years, the organism or structure does not manage to keep its capabilities intact. In this way, it loses functionality, efficiency, force , among other possible factors, while simultaneously increasing their vulnerability.
It is easy to understand the notion of senescence if we think about the life of a human being . From birth to a certain age, people experience a development process. However, then an inverse process begins, which can be defined as senescence or aging. It is difficult for the individual who is getting older, for physical reasons, to perform tasks that were once simple. It gets more tired, has less strength, moves more slowly and is more vulnerable to disease.
Although senescence cannot be stopped or reversed, it is possible to carry out certain actions that help minimize or delay their effects .
It is known by the name of cell senescence at process which begins as a direct consequence of the damage and stress that takes place in a cell, and it is an alternative way of responding to what is called apoptotic cell death (the destruction that the organism programs to control its own growth and development). This process is essential for the suppression of cancer cells and is also linked to the task of repairing tissues and their inflammations, all related to the development of tumors.
On the other hand, cell senescence also participates in processes such as promotion of cancerous tumors and aging, both with a negative impact on the organism and certainly at the other end of those mentioned in the previous paragraph. This can be taken as a case of antagonistic pleiotropy , a phenomenon that is evident when a gene produces different effects and apparently without any relation to each other.
The first to describe these processes was anatomy expert Leonard Hayflick, born in North America in 1928, in the context of an investigation about the in vitro growth of human fibroblasts (a type of cell that is born and dies in connective tissue , with a framework structure and an essential role when it comes to healing wounds). He then discovered that cells can only go through a maximum of 60 replication cycles, so their increase it is limited, contrary to what the French scientist Alexis Carrel had postulated, according to whom in vitro cultures gave rise to infinite development.
Cellular senescence is a process that can trigger various stimuli, and each of them, combined or individually, can give the same results. One such stimulus, for example, is the shortening of telomeres (the ends of a chromosome), what happens when the enzyme Telomerase in most somatic cells. When working in vitro, on the other hand, it is possible to notice various causes of stress that lead to senescence, such as oxidative stress, serum and inadequate substrates.