Cats are well-known for licking themselves clean, but what happens to all the loose hair and sand and mud and wet substances that the lick off of themselves? Do they ingest everything? Do they cough up and vomit out a furball later with all of this?

I have a pet cat and I've never understood where all that she licks off of herself is going.

How is a cat's digestive system suited to handle all the inedible environmental substances?