The chemoreceptor trigger zone is a bilateral set of centers in the brainstem lying under the floor of the fourth ventricle.CTZ has connection with vomiting center and play indirectly to stimulate vomiting.. Electrical stimulation of these centers does not induce vomiting, but application of emetic drugs does - if and only if the vomition centers are intact. The chemoreceptor trigger zones function as emetic chemoreceptors for the vomition centers - chemical abnormalities in the body (e.g. emetic drugs, uremia, hypoxia and diabetic ketoacidosis) are sensed by these centers, which then send excitatory signs to the vomition centers. Many of the antiemetic drugs act at the level of the chemoreceptor trigger zone.

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