Why there are no feedback loops in aging?
Some gerontologists insist that aging is a process, in which "nothing is clear, everything is connected to and affects everything". This position obstructs the search for patterns and the development of treatment. It could appear true at the first sight, because metabolic pathways are formed from a large amount of cycles and feedbacks, similar to gene maps.
But there is a way out of this vicious circle. Aging is unidirectional process. It has a beginning and, alas, has an end. The aging process manifests gradually, so its every step can affect only the subsequent stages. Every stage of aging has a date. A process that happens at 35 years can not cause a process, already passed at 25.
General aging and distinct physiological processes should be distinct from each other while aging is discussed. The dormer is unidirectional prolonged aggregate of processes, the latter are separate short-term qusistatic processes with a lot of feedbacks, but they both are prolonged in time and have a beginning and an end.
Our aging diagram provides a clear picture of aging manifestation along the timeline and position of various processes.
We avoid showing feedbacks not because we do not know about them. The reason is that creation of sufficiently generalized aging diagram requires to omit the description of feedback at this stage.
Feedbacks are obviously essential part of human metabolism. But there is a way of visualising only the direct links. This way implies transition to the new system-level of process consideration. Let's see an example.
The aging reduces protein synthesis, including ribosomal proteins. This reduces the amount of ribosomes, and that reduces the protein sythesis. This is classical example of feedback.th
But we can avoid the loop by detecting causal link at other level. For example, the external cause A decreases the protein synthesis. As a result, the amount of ribosomes falls. This is the cause of the decrease in the quantity of proteins, that is triggering the process B. In this case we shift to the level of A-B link. We do not need a feedback to descript a process at such level.
Also, I want to say that we need to draw a dark line (or something else) to mark the moment of death. As I understand, in this case it will correspond with the maximum life span for human.
Аuthor: Medvedev D., 23.07.2010 г.
Human Aging System Diagram, version N43, from July 23, 2010
Medvedev D.A., Ph. D, Artyukhov I.V., Kaurov B.A., Krementsova A. V., Moskalev A.A., Sarvilina I.V., Pharm. D Pasjukova E.G Moskalev A.A. Udalova V.V. (Valerija Pride), Ezhov M.D., Ilyin P.A.,