Why is Carbon, the building block of life, safe when eating or drinking (carbonated water), but not when breathing (carbon monoxide or carbon dioxide)?

Question

Why is Carbon, the building block of life, safe when eating or drinking (carbonated water), but not when breathing (carbon monoxide or carbon dioxide)?

In: Biology

Answer 1

Lots of poisons are chemically “close enough” to another chemical that our body does use that they can make it into our bodies, but once they’re in they’re not chemically close enough to do the task they’re supposed to.

CO is one of these. It is chemically able to bind to hemoglobin, very well in fact. But when it gets to where our body wants to use it it’s not close enough to O2 for our bodies to metabolize it, and it’s not close enough to CO2 for the gas exchange in our lungs for our bodies to be able to easily remove it.

So a CO molecule sticks to the hemoglobin with no easy way to dislodge it, basically wiping out a red blood cell.