as stated in title, for example, why do red blood cells live and die in a matter of a few months, but cardiac and oocyte cells last for up to 50 years? i understand it has to do with telomeres somewhat, but vaguely. can anyone elaborate?
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Sometimes it is because what the cell is doing is inherently so damaging that they break apart quickly I need to be replaced. That is what is driving the quick turn over of your red blood cells.
In other cases it is what is known as thanatosis, or programmed cell death. This is more common in cells which are not destroyed by what they are doing, but which still need to be broken down and replaced for onereason or another. For instance, the cells that make your bones are replaced because even though they are not being damaged, you constantly break down and reabsorb your bone in order to keep your bone strong.
For cells that don’t have either of these issues it is usually better to just keep them going as long as possible so they don’t tend to have a shelf life. Your neurons and muscle cells are almost all the same ones you were born with.
The issue with telemeres is not the life of a single cell, but rather how many times the cells of your body can reproduce before they stopped being able to. This will never be an issue for long-lived cells, but for cells that have to divide more quickly like the cells which produce your blood cells, then with them it ultimately sets a limit on how long you or any other organism can live.
Usually, the cells that have a long lifespan have structures that make it prohibitively difficult for the body to replace them. When dealing with heart cells and neurons, for example, removing one of them has consequences for either the structure that they’re a part of or for the extremity that they’re attached to. Their associated organ doesn’t function properly until a new cell comes in to do the job of the old one. And the organism could more easily die before that happens.
Blood cells and epithelial cells, on the other hand, are specifically designed to be lost. Your epidermis and your intestinal lining undergo a lot of mechanical friction and/or damage. The body might have the option of making them more resistant to that damage, but that would work against their absorptive or regulatory functions that are also necessary for its systems to work.
Blood, likewise, has a tendency to leak out when something is damaged, so it’s better to constantly replace old cells rather than just let them keep working. In fact, the destruction of old blood cells is necessary for production of bile and other necessary chemicals. What’s more, the red blood cells of warm-blooded animals have their nuclei destroyed when they’re originally created so that they can contain more hemoglobin to fuel the body. So, even if it were a good idea to save the cells for as long as possible, there’s no way to really do so.
So, yeah. The cells live longer or shorter depending on what they’re meant to do.
Certain human cells live longer than others due to factors like their functions and the presence of telomeres, which protect against cellular aging. For example, neurons and heart muscle cells are long-lived because they don’t undergo frequent cell division, while skin cells and blood cells have shorter lifespans due to their rapid turnover and exposure to external factors.
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