Bilateral Vomitation Center

Of all the mysteries that remain of the human brain, the seat that controls vomiting is not one of them.  Buried deep within the reticular formation of the medulla, that archaic reptilian complex , the bilateral vomitation center reacts to stimuli sent from the digestive tract signalling nausea.  Depending on how great the nausea is, a tipping point may be reached where retching, or heaving, begins, usually followed by vomiting.  Anyone who has ever vomited knows how singularly unpleasant an experience this is, and typically most people who aren't bulimic try to avoid this action at all costs.  I remember one episode as a child, crouching before the toilet, my mother holding my head, and me begging, "No more, no more,"  but there is no bargaining with something that's an involuntary function.  It's going to do what it's going to do, completely oblivious to your suffering, while you languish in the hell of your awareness.
*As a footnote, while writing this my mother called me to tell me that she's got the stomach flu that's going around and was up half the night vomiting.  When I tried to explain to her how this all functions, she said that she had to go.  Knowledge is power!