is typically not classified as a CVO. Sensory organs Area postrema Anatomy The area postrema is located in the caudal medulla oblongata near the junction of the brainstem and the spinal cord. In humans and in most other mammals that have been studied, it consists of swellings on either wall of the fourth ventricle. In rodents and lagomorphs, however, the area postrema forms a midline structure dorsal to the obex. When viewed histologically for its capillary distribution and morphology, the area postrema has numerous subregions separated according to capillary permeability, rates of blood flow, and duration of blood transit through respective capillary beds. Function Relatively little is known about the function of the area postrema in humans. However, there is strong evidence that the area postrema acts as the chemoreceptor trigger zone for vomiting, which is triggered by the presence of noxious stimulation from the blood. There is also evidence that the area postrema is the site at which angiotensin stimulates glucose metabolism, presumed efferent neural activity, blood pressure control, and thirst. The area postrema also has integrative capacities that enable it to send major and minor efferents to sections of the brain involved in the autonomic control of cardiovascular and respiratory activities. Vascular organ of the lamina terminalis Anatomy Classified as a sensory circumventricular organ (along with the SFO and AP), the vascular organ of lamina terminalis (VOLT) is situated in the anterior wall of the third ventricle. Characteristically of the CVOs, it lacks the tight endothelial blood brain barrier. The vascular organ is further characterized by the afferent inputs from the subfornical organ (SFO), the median pre-optic nucleus (MnPO) region, the brainstem, and even the hypothalamus. Conversely, the vascular organ of the lamina terminalis maintains efferent projections to the stria medullaris and basal ganglia. As a major player in the maintenance of the mammalian body fluid homeostasis, the VOLT features the primary neurons responsible for osmosensory balance. These neurons, in turn, feature angiotensin type I receptors, which are used by circulating angiotensin II to initiate water intake and sodium consumption. In addition to the angiotensin receptors, the neurons of the VOLT are also characterized by the presence of a nonselective cation channel deemed the transient receptor potential vanilloid 1, or TRPV1. Though there are other receptors within the TRPV family, a study by Ciura, Liedtke, and Bourque demonstrated that hypertonicity sensing operated via a mechanical mechanism of TRPV1