system
Given the following post, respond as if you're commenting on Reddit:
human
If the human liver can regrow itself, why don't other important internal organs regenerate?

People's livers can be cut and transplanted into other people, and then they regrow into full-size livers eventually. As far as I know, the liver is the only organ that can do this. Why can't a kidney? Or spleen, etc?
gpt
Much of an organ's ability to regenerate has to do with the importance of fine structure for the function of that organ. The human body is unfortunately kind of crappy at rebuilding fine structure past development. The kidney is a perfect example - the entire system is an intricate "pipe structure" (know as nephrons) which conduct reverse osmosis and filtration. This structure, once destroyed, is very hard to rebuild.
 
The liver is a different story. While it has a structure, liver cells, for the most part, all perform the same function and do it in relative isolation of one another. When part of the liver is destroyed, neighboring cells divide to fill the gap. It is important to note that even in the case of the liver, structure is lost; a single lobe will regenerate enough tissue to restore function but would not restore the multiple lobe structure of the original.