If an athlete exercising intensely in hot conditions doesn't rehydrate sufficiently, which effect results when plasma osmolality exceeds a critical threshold?

💡 Explanation

Elevated plasma osmolality triggers the osmoreceptors, stimulating the release of vasopressin (ADH) from the posterior pituitary. This increases water reabsorption in the kidneys, concentrating urine and reducing water loss because ADH promotes aquaporin insertion in collecting duct cells; therefore, water is retained rather than excreted, while the other hormonal mechanisms would counteract dehydration.

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