<P> An osmoreceptor is a sensory receptor primarily found in the hypothalamus of most homeothermic organisms that detects changes in osmotic pressure . Osmoreceptors can be found in several structures, including two of the circumventricular organs--the vascular organ of the lamina terminalis, and the subfornical organ . They contribute to osmoregulation, controlling fluid balance in the body . Osmoreceptors are also found in the kidneys where they also modulate osmolality . </P> <P> Osmoreceptors, sense change in osmotic pressure . When the osmotic pressure of blood changes, becoming more dilute or more concentrated, water diffusion into and out of the osmoreceptor cells changes . The cells expand when the blood plasma is more dilute and contract with higher concentration . This causes a neural signal to be sent from the hypothalamus, which increases or decreases vasopressin (ADH) secretion from the posterior pituitary to return blood concentration to normal . </P>

Where are the osmoreceptors that detect dehydration located
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