Not long ago, one of my doctor friends invited me to sit in on an open-heart bypass and aortic valve replacement surgery, and on a brain tumor removal surgery. It was my first time seeing any sort of surgery first hand, and it was PRETTY DAMN COOL. I now know that I would have aspired to be a surgeon had I gone into medicine.
The heart surgery was straightforward, and looked like it required a lot of coordination to pull off. The heart had to have some threads woven into it, an incision made, and a tube thrust into it while it was beating all over the place. I also saw blood squirt out of arteries -- I had heard that it was pretty high pressure, but I was surprised at how far it could squirt!
I had no idea what was going on in the brain surgery. There was a hole in a head, and the surgeon was cutting stuff out of it. It all looked like mush. I'm told that it's easier to tell what's what before everything gets smeared with blood.