Osmoreceptor


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osmoreceptor

[¦äz·mō·ri′sep·tər]
(physiology)
One of a group of structures in the hypothalamus which respond to changes in osmotic pressure of the blood by regulating the secretion of the neurohypophyseal antidiuretic hormone.

Osmoreceptor

 

a terminal structure of sensory nerves that reacts to changes, in the concentration of osmotically active substances, that is, to changes in osmotic pressure in the surrounding fluid. Osmoreceptors are found in various animal organs and tissues, such as the liver and pancreas. Impulses from osmoreceptors reach the divisions of the central nervous system that participate in the regulation of water-salt metabolism. Osmoreception is controlled by neurons of the supraoptic nuclei in the hypothalamus. These neurons can perceive fluctuations of as low as 1–2 percent in the osmotic pressure of plasma, and when the osmotic pressure increases, they elaborate the hormone vasopressin, which is stored in the hypophysis. Vasopressin, the antidiuretic hormone, alters the permeability of the walls of the renal tubules when it is released into the blood, thereby reducing the amount of urine excreted.

References in periodicals archive ?
Again, it would seem unlikely that ANP would differentially affect thirst and AVP osmoreceptor neurons.
Osmoreceptors or sodium receptors activate circuits that subserve thirst and sodium appetite, and a parallel inhibitory circuit of sodium appetite involves the LPBN.
However, this center has a higher set point than the osmoreceptors and responds to osmolalities[greater than] 290 mmol/L.
Osmoreceptors in the hypothalamus respond when plasma osmolarity changes by as little as one per cent, first stimulating ADH release and then thirst.
The noradrenergic neurons (A2 group) of the nucleus tractus solitarius (NTS) that receives projections from carotid afferents and peripheral osmoreceptors have been highlighted among these regions [12,13].
When plasma osmolality rises, it stimulates osmoreceptors located in the hypothalamus, which, in turn, sends signals to the vasopressin synthesizing cells located in the supraoptic and paraventricular nuclei of the hypothalamus.
Dry mucous membranes, hyperosmolality, and reduced plasma volume activate hypothalamic osmoreceptors, which trigger thirst and stimulate the secretion of ADH from the posterior pituitary.
Alternatively, mouthpart osmoreceptors might provide information about the chemical quality of prey items.
Water-permeability of the late distal tubule is influenced by antidiuretic hormone (ADH), which is produced by the hypothalamus and released in response to input by systemic baroreceptors, osmoreceptors, and angiotensin II.
Strategically located near the supraoptic nuclei of the hypothalamus are osmoreceptors which create a feedback control system for ADH secretion.
This increase is sensed by osmoreceptors in the hypothalamus which responds by releasing AVP.
and the amphipod Gammarus oceanicus, and Tazaki and Tanino (1973) concluded that the antennae of the spiny lobster Panuliris japonicus have mechanoreceptors that also function as osmoreceptors. There is also evidence that the legs of crustaceans have receptors that provide important information about salinity.