What is the Origin of Chemoreceptor Trigger Zone?

The descriptive name combines "chemoreceptor," indicating its function as a chemical sensor, and "trigger zone," highlighting its role in initiating a complex motor response. This region is anatomically situated outside the protective confines of the blood-brain barrier, a feature that is essential for its surveillance function.

What is the Mechanism of Chemoreceptor Trigger Zone?

The CTZ possesses a high density of various neurotransmitter receptors, notably dopamine D2, serotonin 5-HT3, and opioid receptors. Circulating chemical agents, such as certain medications or metabolic byproducts, bind to these receptors, generating an excitatory signal. This neural impulse is then transmitted to the adjacent vomiting center, which coordinates the complex efferent pathways leading to nausea and vomiting.

Chemoreceptor Trigger Zone ∞ Area

Chemoreceptor Trigger Zone

Meaning

A specific, highly vascularized region located in the postrema of the medulla oblongata in the brainstem, which acts as a crucial sensory area for systemic chemical imbalances. The Chemoreceptor Trigger Zone (CTZ) monitors the blood and cerebrospinal fluid for circulating toxins, drugs, and endogenous substances, including certain hormonal metabolites. Its primary physiological role is to initiate the emetic reflex in response to these chemical stimuli.