How And Why Do We Age - The Aging Process

Aging is caused by insufficient adaptation and repair mechanism of the body!
The organisms have 3 big phases:
1. Embryonic phase which is strictly regulated, and the most evolved, and well genetically controlled phase of living organisms
Any small error will create dead embryos
2. The growing to sexual maturity phase.
It is a phase in which the genes are very well controlled to avoid disease, to offer maximum performance.
This phase already contains errors and wrong behavior of the cells metabolism. If the accumulation rate and degeneration is smaller than the reproductive maturation time, they will not be eliminated by evolution and will have bad consequences on old people, and in the end will kill them.
3. Post reproduction age, the gene expression is no longer controlled by evolution, the body try to maintain the gene expression of the young body (which is not a necessary good thing in the long run), but some new random effects of genes can have catastrophic effect on the body.
The body have 2 types of cells: replicating cells, and non replication cells(senescent cells, post mitotic cells etc).
This causes 2 distinct phenotype of aging:
1. For replicating cells at old ages, the cells tend to become Senescent, non replication causing a degradation of Immune System, Liver and Pancreas functions, Skin etc.
Telomeres will make many of the cells senescent, but allso genetic errors caused by free radicals.
2. All the non replicating cells suffer a slow degradation because of the constant accumulation of proteins, metabolism waste, cross linking, AGE products etc. Their functionality is decreased and eventually the cell will die: Neuron and Muscle cells.

 
 
Aging can be define as the process in which the organs functions are declining.