Thanks for you patience! I've been working on new models and the app is just about ready for release. Along with a cat heart, you can now explore the hearts of a shark and mudpuppy. There's also a bell-ringer style quiz component to help students prep for those dreaded exams. I have a few small changes I want to make after my last round of usability tests but the app should be submitted very soon
@Naosum, I'm also working on some follow up apps on human anatomy; the first being a really detailed interactive brain. I always had difficulty working out the 3D landscape of the brain in my own anatomy classes, so I hope students like yourself get a lot out of it. More updates soon!