Synchronizing wordpress registration

I have a client who is setting up a wordpress blog within a larger site. She would like it so that users only need to register once, instead of once for the site and again for the blog.

I am a PHP/MySQL developer, but I have never worked with wordpress before.

Would doing this be as simple as adding the user’s information into the wordpress db upon registration, essentially skipping the need for the wordpress registration? Or are there any challenges I have to deal with?

I’d like to see what the wordpress database(s) look like, but cannot find any schemas on the internet.