thirst

n. the sensation caused by a need for increased fluid intake to maintain an optimum balance of water and electrolytes in body tissues. Water is lost from the body mainly in urine, through sweat, and via the lungs. Dehydration causes a reduced production of saliva and the feeling of a dry mouth. In addition, a specialized area of the hypothalamus in the brain detects and responds to the changes in osmotic pressure that result from increased concentration of electrolytes in extracellular fluid subsequent to water loss (see osmoreceptor). See also hypovolemic thirst; osmometric thirst.

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Psychology term of the day

January 26th 2025

congenital oculomotor apraxia

a condition, present at birth, in which a child is unable to fixate objects normally (see oculomotor apraxia). It is characterized by the absence of saccades and smooth-pursuit eye movements in the horizontal plane, but vertical eye movements are preserved: Children with this condition are often mistakenly thought to be blind. Between the ages of 4 and 6 months, they develop thrusting, horizontal head movements, sometimes blinking prominently or rubbing their eyelids when they attempt to change fixation. The cause of congenital oculomotor apraxia is unknown, but there is usually an improvement with age.