Re: the question of autopsies and violent fights, I couldn't help thinking of the Weegee show at the International Center of Photography, "Murder is My Business," which I thought was very interesting and well presented. Would the question of whether it was art or crossed some line come up if we were talking about painting? What subjects would be "over the line"? Crucifixions? Martyrdoms? Certainly, out of their contexts, they are merely obscene examples of violence. But given context, they have meaning, and exemplify sacrifice, faith, etc. On pornography vs art, I'm not sure if there is a sharp line. But two general suggestions: 1. I think it is easy for something to be art. All it needs is to hung on a wall, titled - even "untitled will do", discussed in the context of art, etc. But that is not to say that anything that is classified as art is either worth looking at or taking seriously, or that anything worth looking at should be classified as art.
Someone (?) once wrote that the difference between pornography and art was that pornography had no subject, only content. I think there is something right about that. I like puppies, so I'll probably like looking at any pictures of puppies, even pictures I would classify as "bad," (let it be as subjective as you please). I am looking at the puppies depicted, not judging the picture. In other words, my reaction is toward the puppies, not the work. To the extent that my reaction is also toward the work in which the puppies stand as subject, I am valuing it as art. I think there is a good analogy to be drawn with pornographic images, or landscapes, etc. If you are reacting only to what it is a picture of, you are not treating it as art.
Sorry I've gone on so long.