A hiker stranded in a desert with limited water experiences increased plasma osmolality. What effect dominates as this osmolality climbs?

💡 Explanation

Increased plasma osmolality triggers hypothalamic osmoreceptors, which stimulates ADH release and thirst. Because the brain detects higher solute concentration in the blood, thirst becomes a powerful driver to replenish fluids; therefore, hypothalamic osmoreceptor activation leading to thirst is the dominant effect, rather than reduced ADH or RAAS suppression.

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