chemoreceptor trigger zone

… centres—the vomiting centre and the chemoreceptor trigger zone—both located in the medulla oblongata. The vomiting centre initiates and controls the act of emesis, which involves a series of contractions of the smooth muscles lining the digestive tract. These contractions begin at the small intestine and move successively through the stomach…

…may act by depressing the chemoreceptor trigger zone, which is located in the hypothalamus of the brain and controls vomiting.