Why is there material from the small intestine in vomit?
A. As mentioned above, stomach acid is very strong. One of the main functions of the stomach is to disinfect that which is entering the body, and it uses a powerful level of hydrochloric acid to soak the food sterile. Ask any heartburn sufferer about the power of stomach acid. In an important step approaching the climax of the vomiting process, the vomiting center issues a command to have the small intestine send a fair portion of its contents back into the stomach. This starts about one minute before vomiting and lasts about 45 seconds.9 (For those who cherish bits of trivia, this is called the retrograde great contraction.) This has the effect of neutralizing the vomit,10 making it less damaging to the esophagus, throat, mouth, and teeth. Some researchers contend that expulsion of the intestinal content is a necessary part of the vomiting act in itself [since the intestine is where the toxin was detected by the CTZ], and that the movement into the stomach puts it in place for being e
