Funnily enough, we can control our bleeding more directly. .

Think vasoconstriction. If you can learn how to access your bodies ability to use vasoconstriction it can work pretty well. I've met a guy that knows how to think bleeding away (while he was awake at least, he would start bleeding again in his sleep). I've also used suggestion to help stop my girlfriends bleeding to surprising success (the doctor asked why the cut hand was so cold!).

While the main point of "you can't just bark orders all the time" stands, it does point out anther avenue for turning indirect work into a fairly direct avenue through being more aware of what your body functions feel like so that you can communicate with them.