Arguments in favour of the concept of critical threshold of accumulation of errors in cell death. Qualities and limits of this concept in cell aging

: The concept of critical threshold of error accumulation explains how a cell dies when it it confronted, abruptly or after a certain accumulation time, to a level of errors which is not sustainable anymore for the cell. Arguments in favour of this concept will be developed, which have mostly arose from the study of the cellular system of free radical production and elimination but also from the system of free energy production and utilisation. On one hand, this concept cannot explain how the level of errors can increase during normal ageing, in which cell death is not necessary involved. On the other hand, this concept can be a basis to explain the occurrence of some age-related pathologies where the relative resistance of the various cell types constituting an organ to intense stresses can be responsible for the occurrence of dysfunctions in this organ. The main point is that this concept takes into consideration the relative level of the defence systems confronted to the stress. Such a consideration of the cellular defence systems constitutes the basis for a global theory of cellular aging explaining how the level of errors can progressively increase with time, spontaneously of after intense non lethal stresses.