As the cells ages, they divide and repair slower.
Telomeres: These are the protective ends of chromosomes, they shorten with each division. When they become to short the cell enters a non-dividing state. The term "cellular timekeepers" means something that measures the amount of time taking, this is similar to telomeres which keep track of the amount of divisions being made.
(NCBI, Cell Aging and Death, 2016)
Apoptosis:This is a controlled dead that maintains tissue health.
(NCBI, Cell Aging and Death, 2016)
A large amount of senscent cells leads to tissue degeneration and age-related diseases.
(SENS Research Foundation, Overview of Cell Secescence, 2020)
Bibliography:
Image Hyperlinks:
sph.bu.edu- Telemores
Biology Online- Cell death
National Insitute on Aging- Connection to aging