How Long Does a Human Head Actually Remain Conscious After Being Cut Off?

A relevant article.
https://www.businessinsider.com/italian-...ent-2016-9

In terms of rejection, there isn't. However, when you think about it...while this is meant to preserve the function of the head, rejection will come from the body and it will be the head which suffers the ill effects. 

Linda

Well, in that case the best thing to do is quit while you're a head.