Why do we vomit when we drink too much?

There are two reasons.  The first reason is that alcohol can act as a local irritant to the lining of the stomach, causing “gastritis”.

The second reason is that our brain has a “vomiting center”, also known as the “chemoreceptor trigger zone”.  It is located in the medulla portion of the brain.  When our vomiting center senses a high level of toxins in the blood, such as alcohol, morphine and other drugs, or infectious agents such as a virus that could be bad for us, it initiates emesis, or vomiting.

The vomiting center is linked to the nervous system including the nerves to the skin, respiratory system,  stomach, and the abdominal muscles.  When the vomiting center activates our nervous system, we first become pale and sweaty.  At the same time, the nerves to the stomach and abdominal muscles cause contractions, and start the act of vomiting.

Your vomiting center can actually save your life!  When a very high alcohol level is sensed, the vomiting center protects us by vomiting out whatever alcohol is in the stomach, in an attempt to protect the body from its toxic effects.