Figure 7.The relationship of thirst to plasma osmolality during controlled hypertonic stimulation. Data obtained from analysis of thirst (by visual analogue scale) during progressive hypertonicity induced by infusion of 855 mmol/l saline in a group of healthy adults. There is a linear relationship between thirst and plasma osmolalities in the physiological range, defined by the function: thirst = 0.39 (plasma osmolality – 285), r = +0.95. The shaded area represents the range of normal response.