I was wondering why professional cameras are so big?

I'm referring to the kind used to shoot TV shows and movies. Every year, Nikon, Kodak, and others make smaller and smaller cameras for personal use, but the professional kind never get any smaller.

More big more good image resolution!

There must be a reason - is it that the consumer wants cheap and light but the pro needs quality? Yeah, maybe

The large majority of them still use 35mm movie film. The big thing on the back is the canister of film, miles of film all rolled up. Then time code, light and mic rigging, daily monitor out cable… Literally truckloads of stuff just for the photography part of a film (camera, lights, sound etc).

Actually, an episode of "House" was shot with a Canon 5D MkII DSLR camera, but even it requires lots of extra equipment to do it well.

True quality equipment can't always be miniaturized. Modern technology can do some wondrous things, but the kind of equipment needed to give you those great looking tv shows and movies in a theatre is extremely complex with a vast amount of high tech electronics. It just simply can't be made to be tiny and do what it needs to do. Be glad you don't have to wrestle those things around!

You may think they are big now but they were much bigger in the past, see the link below. 35mm film cameras and studio TV cameras are bigger than consumer cameras for several reasons. One of them is the physical size of fast wide aperture zoom lenses, the lenses just need to be that size due to the laws of physics. And film cameras need to have a film magazine attached. A 1000 foot magazine of film only lasts about 11 minutes at 35mm sync sound speed. 16mm cameras are smaller but are not usually used for big films. Believe me the camera companies Panavision and and ARRI know what they are doing but the industry is moving quickly to high quality digital cameras like the Red. See links.