why isnt my body mine?

why can't I sell my organs? they are mine arent they? why can I not do with them what I choose? just like the prostitution laws are all about telling me what I can or cant do with my body, now they tell me I cant sell my organs. I just dont get all this government all up in my bidness stuff. how did these laws ever get on the books? when did we give up rights to our bodies? We cant kill ourselves, can't have someone else do it for you either. we cant sell our body for sex. we cant sell our organs. why cant I use MY BODY as I see fit? isnt it mine? I have freedom of speech but not if its to make a deal to sell my kidney. I have freedom to bear arms, but not if I am going to harm myself. I have freedom to pursue happiness unless it includes having sex for money. I think something is really screwy around here.