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sensation indicating the body's need for water. Dry or salty food and dry, dusty air may induce such a sensation by depleting moisture in the mucous membranes of the mouth and throat. Relief through ingestion of water is only temporary, however, if thirst results from a generalized depletion of water in the system. About three fourths of the body is composed of fluids, and the average adult requires 2 1-2 qt (2.4 liters) of fluid per day, supplied by water, other beverages, and foods. Depriving the body of water interferes with its metabolism and functions, causing dehydration, which is eventually fatal. The unnatural thirst that accompanies fever, diabetes, and other disorders is caused by a rapid reduction of the body fluids. The sensation of thirst is controlled by osmoreceptors in the hypothalamus in the brain. Dehydration of the cells triggers the posterior pituitary to releast the antidiuretic hormone (ADH).



the urge to drink, the physiological state that regulates intake of water into the bodies of animals and humans.

Intensity of thirst is determined by the duration of water deprivation, water losses in urine and perspiration, and the quantity of table salt consumed. In humans thirst is manifested by a sensation of dryness in the mouth and throat. It is conditioned by the thirst center—a set of nerve cells located in various sections of the central nervous system (the hypothalamus, the limbic-reticular system, the cerebral cortex) and associated with complex reflex reactions arising after stimulation of the central and peripheral interoceptors that respond to changes in osmotic pressure and volume of extracellular and intracellular fluids. Usually, the appearance of thirst precedes dehydration of the body, and relief of thirst occurs long before the entry of the water imbibed into the tissues, merely as a result of the act of drinking, the wetting of the mouth and throat, and the distension of the stomach walls. Thirst may also arise during digestion, since during this process water from body tissues enters the lumen of the digestive tract. Considerable intensification of thirst is observed in certain nervous and endocrine diseases, disorders of the water-salt metabolism, changes of the electrolyte con-tent in the blood, and edemas of cardiac origin.


Kravchinskii, B. D. Fiziologtia vodno-solevogo obmena zhidkostei tela. Leningrad, 1963.
Handbook of Physiology. Section 6: Alimentary Canal. Vol. 1: Control of Food and Water Intake. Baltimore, 1967.



A sensation, as of dryness in the mouth and throat, resulting from water deprivation.


Ancient Mariner
he and his crew nearly die of thirst. [Br. Poetry: Coleridge The Ancient Mariner]
References in classic literature ?
Nine days passed, and I was weak from hunger and thirst, but no longer suffering--I was past that.
Our only enemies were heat, thirst, and flies, but far rather would I have faced any danger from man or beast than that awful trinity.
It would be better to die walking that to be killed slowly by heat and thirst in this dreadful hole.
Tarzan went to the brook first, and slaked his thirst.
Although he had not howled once, his snarling and growling, combined with his thirst, had hoarsened his throat and dried the mucous membranes of his mouth so that he was incapable, except under the sheerest provocation, of further sound.
The circle shrieked with glee, and what Jerry's thirst had been before was as nothing compared with this new thirst to which had been added the stinging agony of pepper.
Nothing remained to him but his thirst, a prodigious possession in itself that grew more prodigious with every sober breath he drew.
It is foolish to go mad from thirst and fall by Apache bullets, or be skinned alive--it is in bad taste.
Well, I said, and hunger and thirst, and the desires in general, and again willing and wishing,--all these you would refer to the classes already mentioned.
Admitting this to be true of desire generally, let us suppose a particular class of desires, and out of these we will select hunger and thirst, as they are termed, which are the most obvious of them?
Bitterness is in the cup even of the best love: thus doth it cause longing for the Superman; thus doth it cause thirst in thee, the creating one!
I slaked my thirst at the brook, and then lying down, was overcome by sleep.