I wasn't entirely sure that the age of an organ affected it's function.
Like say a Liver or a Pancreas or whatnot....but those are affected by lifestyles and other types of ailments/environmental conditions.
I'm sure you'll agree that organs are composed of cells.
"To date, telomere shortening has been observed in most dividing somatic cells, eventually leading to cell senescence when critically short telomeres are reached."
Next comes apoptosis, i.e. programmed cell death.