How does your stomach 'know' when to throw-up?

"At least after death you're not nauseous." Woody Allen in Sleeper

First, here is my WIKI / MAYO level understanding of the process, in all its elegance.

First, an area of the brain called the chemoreceptor trigger zone (CTZ) is stimulated by substances in the blood which in turn causes the activation of the Parasympathetic (rest and digest) and Sympathetic (Flight/Fight) Nervous Systems (PNS, SNS). Then the pyloric sphincter relaxes, and the abdominal muscles contract to expel the contents of the stomach. Then Emesis. Thats, heave, then ho, then BLEAH...

So in an over summarized process, something tells the brain, which tells the nerves, muscle things happen, then a roster tail appears. Got it (will kinda)- Now, thats not my question.

• It seems the following two are mechanical in nature and we have a 'sensors' that know when and how to communicate to the CTZ (vestibular system and the vagus nerve). These make sense.
  • Gag reflex
  • Motion sickness
• Also following sub-list, I call I feel have a layman understanding as well (or at least the belief that it is knowable). Other parts of the brain can trigger this process. Probably has some evolutionary basis as well (defensive vomiting is indeed a thing).
  • Nerves / Fear.
  • Taste(too much fat), Smells(rot), Sights(Blood, gore)
• Hormones and Viral and Bacterial infections.
  • Gastroenteritis

• But this one confuses me. How after a few short minutes or hours does food poisoning cause this process.
  • Food poisoning