Thirst motivation, like that of hunger, is regulated by peripheral and central nervous system mechanisms. In part, thirst regulation involves
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both the intra‐ and extra‐cellular water content of the cells in the body
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a chemical (angiotensin) produced by the kidneys
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a hormone (antidiuretic hormone (ADH), also called vasopressin) produced by the pituitary gland
Central nervous system structures such as the subfornical organ and the LH (lateral hypothalamic nucleus) also help regulate thirst. Damage to the LH causes the animal to become adipsic (fail to drink) as well as to become aphagic (fail to eat). The double depletion hypothesis contends that thirst is produced by depletion of fluid both outside and within cells.