Endocrinology/VasopressinADH/ControlToWaterIntake/basic

POINT!

With water intake, the (red→blue) negative feedback decreases (the synthesis, secretion, and blood concentration of) vasopressin (anti-diuretic hormone, ADH).

1st star (illustration): Subject sweated. With water intake, plasma osmolarity decreases. ① Water intake decreases plasma osmolarity (diluted, hypotonic), and water reabsorption (through the water channels, which are increased by vasopressin, ADH) decreases plasma osmolarity. These effects are in the same direction (red).

② Since these effects are in the same direction (red), negative feedback decreases (blue) (the synthesis, secretion, and blood concentration of) vasopressin (anti-diuretic hormone, ADH). This decreases the number of water channels and the water reabsorption. The plasma osmolarity-decreasing effect of the water reabsorption becomes weaker. This will lead to a reverse in the decreased plasma osmolarity (diluted, hypotonic) produced by water intake, increasing it towards normal (baseline, isotonic) osmolarity.

Challenge Quiz

1.

Water intake increases decreases  正解! plasma osmolarity, and water reabsorption (through the water channels, which are increased by vasopressin, ADH) increases decreases  正解! plasma osmolarity. Since these effects are in the same opposite  正解! direction, negative feedback increases decreases  正解! (the synthesis, secretion, and blood concentration of) vasopressin (anti-diuretic hormone, ADH).