<human>: Condense the text into a few key points

I'm in the United States. California, if that's relevant. I know that via durable power of attorney, one can appoint someone to make medical decisions in the case of an emergency.  However, I want to know if there is a way to, without specifically appointing anyone, to deny that right to specific people.  

I do not get along well with my family.  We have very different points of views on what is and isn't right for my own well being, morals, etc.  I do not want them to have the ability to override my judgement if I am in an emergency, or unable to communicate.  I also do not have anyone I would like to give power of attorney to (I'm young, don't have any life partners, friends close enough to give this to).
<bot>: I do not want my family to, in any context, make any medical decisions about me.  Is there a way to prevent them from doing so without designating a specific agent as having power of attorney?