If every cell in your body is replaced roughly in 7 years, why do the affects of smoking and other bad habits still affect people who quit?
In: Biology
First, those “7 years” are just an average between “every couple of days” and “never” someone took at one time that got misquoted over and over again. And it wasn’t even very useful to begin with, given the wide range between different types of cells.
Second, cancer is what happens when making a new cell goes wrong. So, cells being replaced is actually a bad thing. For example, the brain, which rarely replaces cells, is pretty cool with radiation, whereas your stomach and colon lining will go cancerous with even small amounts of it.
Third, plenty of the damage in the lung is not cell-based. Just like you keep scars on your skin forever, damaged structures in the lungs will not regrow either. There are very few places in the human body where macroscopic damage will fix itself. Your tongue and gums can do it to some extent.
Fourth, some of the aftereffects are from substances that remain in the body or from changes they caused that will persist. For example, a stunted growth (as can happen when kids smoke) will not fix itself by giving a grownup a growth boost when they stop smoking.
Latest Answers