How does your body know when to vomit?

Interesting question. The causes of vomiting are numerous and not limited to the stomach. For example, everyone is familiar with vomiting due to motion sickness. The physiologic response of vomiting itself is highly coordinated, with signals from the brain orchestrating the pattern. Basically, the chemoreceptor trigger zone in the brain is activated by noxious substances, triggering the vomiting center. Oila.

Also many of my patients vomit when experiancing shock. Due to shunting blood to vital organs and oxygen being depleted to the digestive system. The body then purges itself so food does not rot in the system.

For me, it’s any time I hear George Bush speak.

vommiting is a pretty complex thing
there are chemical signals, both inside the digestive system, and through the blood to the brain that can trigger vommiting. But there are also many psychological triggers to vommiting. I once got very ill eating sweet potatoes, and to this day the smell of cooked sweet potatoes turn my stomach. I tried to eat them once again, but they wouldn’t even go down my throat – my brain remembered the food as “bad”, even though the sweet potatoes themselves were not bad, and would not permitt them inside.
also the fight or flight response can shut down digestion, and if the stomach is full, it may vommit either to empty dead weight, or possibly at some point vommiting on a predator may have distracted them (like an octopus jetting ink), and evolutionarily we haven’t lost it. that’s why people can vommit under intense stress, or from seeing shocking things.
just some random thought on vommiting.

Dave, that is an absolutely fantastic answer!

Kudos!

August 30, 2008, 6:03 PM EDT

You guys are so smart.. I love reading new stuff like this.

As an aside, did you know that horses are physically incapable of vomiting?

I understand they can’t fly, either.

August 30, 2008, 6:16 PM EDT

@JackAdams: Why the snark? I thought that was quite an interesting (and on-topic too!) tidbit. No need to lower the tone.

“The gastroesophageal sphincter (where the esophagus empties into the stomach) acts as a one-way valve that only allows food and water to enter the stomach from the esophagus. Horses, therefore, are incapable of vomiting, which [can be] problematic.”

From: http://www.answerbag.com/q_view/117480

@richardhenry: I was engaging in humor. I was told that was OK to do, and that the majority of those in here were smart enough to tell when it was being used.

I’m very sorry that you did not recognize it as such, and I publicly apologize for offending you, as that was never my intention.

August 30, 2008, 7:14 PM EDT

@JackAdams: Was I right in reading the sarcasm there? If so, then I’m on the way to understanding your profound humour one day.

No sarcasm at all.

I’m really very sorry that you couldn’t see the humor in my remark.

August 30, 2008, 7:23 PM EDT

@JackAdams: Oh okay. It confused me when you implied that I was stupid and then publicly apologized. Whatever, let’s shake hands and be friends.

I’ll drink to that.

Please feel free to mention anything about my posts that may bother you, because sometimes I say the wrong thing, and it comes out, other than intended.

I think some refer to it as, “FOOT-IN-MOUTH” disease.

I make mistakes frequently, and after 58 years of living, I have had LOTS of practice, doing so.

I can, with little advance notice, screw-up a free lunch.

August 30, 2008, 7:31 PM EDT

@Jack – I misunderstood your intent, as well. It just seemed snarky and took me aback, especially since I personally find the fact interesting. I was having a hard time understanding the motivation behind the comment.. but thanks for clearing it up.

From what I understand, horses evolved that way because of the time they spend with their heads near the ground, grazing. If they were to vomit in this position, they would choke/suffocate.

@AlenaD: My compulsion towards humor is motivated by a simple desire to laugh, to make up for all those years as a child, where there was no laughter in my household.

Without going into grisly details, beatings and other physical abuse were the norm, and when outside of my home, I did everything I could think of, to make myself smile and laugh.

Unfortunately, that has carried into my adulthood and the need to smile and laugh (and successfully doing both, every day) is what has kept me from attempting suicide, all of these years.

August 30, 2008, 8:14 PM EDT

Yikes. Sorry to hear that you went through that. :(

Nowadays, when I really feel the need for a hearty laugh, I just stand naked in front of a mirror.

I laugh, then cry.

August 30, 2008, 9:14 PM EDT

Right.