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Pathophysiologic pathways involved in emesis

Pathophysiologic pathways involved in emesis
Emesis is mediated centrally by two separate "centers." The chemoreceptor trigger zone (CTZ) is localized to the area postrema in the floor of the fourth ventricle where chemosensitive nerve cell projections are bathed by cerebrospinal fluid that is in equilibrium with blood in the fenestrated local capillaries. Neural pathways project from the CTZ to the nucleus tractus solitarius and the reticular formation of the medulla oblongata, which is the location of the vomiting center (VC). The VC is a diffuse, interconnecting neural network that integrates emetogenic stimuli with parasympathetic and motor efferent activity to produce the vomiting reflex. It receives afferents from the cerebral cortex and higher brainstem, thalamus and hypothalamus, the vestibular system, and via the vagus and splanchnic nerves, the pharynx, gastrointestinal tract, serosae, and other thoracoabdominal organs.
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