In your lungs, hydrogen carbonate ions turn back to carbon dioxide which is excreted when you exhale.
(hydrogen carbonate ions; turn; back to carbon dioxide; L:In your lungs) (carbon dioxide; is excreted; T:when you exhale) (you; exhale; )
hydrogen carbonate ions carbon dioxide you
turn is excreted exhale
back to carbon dioxide L:In your lungs
T:when you exhale