The chemoreceptor trigger zone (CTZ) is an area of the medulla that receives inputs from blood-borne drugs or hormones, and communicates with the vomiting center to initiate vomiting. The CTZ is close to the area postrema on the floor of the fourth ventricle and is outside of the blood–brain barrier. The neurotransmitters implicated in the control of nausea and vomiting include acetylcholine, dopamine, histamine (H-1 receptor), substance P (NK-1 receptor), and serotonin (5-HT3 receptor). There are also opioid receptors present, which may be involved in the mechanism by which opiates cause nausea and vomiting. The blood brain barrier is not as developed here, and drugs such as dopamine which can normally not enter the CNS may still stimulate the CTZ.
Read more about Chemoreceptor Trigger Zone: Evolutionary Significance, Chemoreception, Communication, The Vomiting Center of The Brain, Damage To The CTZ, Antiemetic Medications, Antiemetic Drugs Coupled With Pain Relieving Medications, Chemotherapy
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