I’ve heard that large bones in the human body are naturally completely replaced (regenerated) every 10 or 15 years meaning the bone in your arm today is not the same one you had 10 or 15 years ago. And that these large bones take the longest to regenerate of all other body parts.
Organs such as the heart or lungs take a much shorter time to regenerate. Is there a chart that shows how long each body part takes to renew itself?
I’m trying to tell a friend that if she would just quit smoking today, in X number of years she would have essentially a new set of lungs.
IANAD, nor very medically knowledgeable, but even with the assumption that parts of the body replace their cells completely by certain intervals of time, it needs to be understood that this a bit-by-bit process. That means that when one cell dies and is replaced with another cell, that new cell has to conform at least somewhat to the other surrounding cells. So, the implication of “no lingering damage” due to “a new set of lungs” may not be accurate.
Permanent scars are examples of regeneration/replacement of cells being unable to completely fix past damages.
I think that in most cases, it is the cells already there that create the replacements. If that is the case and your cells already have damaged DNA, so will their replacements.
The brain was long thought to be non-regenerating. Now we are certain that the hippocampus (memory) and olfactory bulbs and a few more are at least regenerating constantly.
In a context different than OP, that sentence can be used for the oldShip of Theseus joke: if lungs and everything else “regenerate” over time–what do they say, we each have a complete turnover of cells every seven years?–I’m not the same I after that period, therefore all my I.O.U.'s are moot.
DNA changes, including the breakdown of telomeres. Every time a eukaryotic cell replicates we lose a bit of DNA from the end of the chromosome. Fortunately telomeres, at the end, are just “junk DNA”. Eventually the telomeres wear away entirely, after about 50-70 cell replications, at which point coding DNA is damaged, and the cell reaches senescence. An aging cell essentially poisons other cells around them. This is probably why the brain “ages”; while many neural cells never replicate, they are supported by glia (“nurse cells”) which do age.
Supposedly many of the cell replication mechanisms are near the telomeres on at least one chromosome, so when those telomeres break down the cell can ironically become “immortal”, replicating out of control.
Anything that damages DNA can cause cancer, not just aging cells. Worse, that DNA damage sticks around. Stopping smoking would “stop the bleeding” but already-damaged cells would still replicate.
I believe some cells in the human body produce a limited amount of telomerase, extending the number of replications before they reach senescence. Cells such as those that line your stomach. Only germ line cells produce enough telomerase to never reach senescence.
The liver is the only organ that can truly regenerate itself. It is possible to lose over 75% of it and have it grow right back (not recommended but completely possible).
It would be great if other organs could do that in the future. Maybe a breakthrough in stem cell research or something like it will enable that to happen in our lifetime but it isn’t the case right now.
I think the OP is talking about something very different than true “regeneration”. Cell exchange may be a better term but that isn’t regeneration. If you remove parts of other organs like the lung, brain or heart, they may heal and even become more functional but they won’t truly regenerate. The parts that are removed are gone for good.
The OP may be talking about the rate that cells die and are replaced in different parts of the body but that is not the same as regeneration. The new cells generally just take the place of worn out ones. The newer generation is the same with slightly more worn out DNA. That is one of the keys to aging process.
Particles from smoke embedded in the lung tissue are not removed by cell replacement.
Daughter cells inherit the mutations that affected the parental cells
As so many have said, the OP overstates the case for “lungs self-regenerate to be as good-as-new”.
OTOH, there’s lots of legit info backing the idea that quitting is helpful and at least partly regenerative. So the OP’s on the right general track even if he’s off-course a bit on the specifics.