preprocess question

I'm relatively new to theming, so please excuse me if this seems to be a naive question. I'm just learning about preprocess functions, and fm finding them very powerful. I understand the concept of a function like mytheme_preprocess_node()... What I'm wondering is if I have a custom content type -- let's call it 'mytype' -- does there exist a function that would look like mytheme_preprocess_mytype_node() that would handle just nodes of mytype. Or would I just use mytheme_preproces_node() and filter out the content types I don't need with an if() clause?

thanks for your thoughts.