ADH increases collecting duct water permeability through aquaporins, restoring water balance when blood is too concentrated in human physiology in human physiology.
Coverage 2012–2025 · Updated 16 Jul 2026
Hypothalamic osmoreceptors detect blood osmotic concentration and adjust pituitary ADH release, changing collecting-duct water permeability.
| Blood condition | ADH and aquaporin location | Urine response |
|---|---|---|
| Too concentrated / low water | More ADH; aquaporins move from intracellular vesicles into collecting-duct cell membranes | More water follows the medullary gradient into blood; low-volume concentrated urine |
| Too dilute / excess water | Less ADH; aquaporins are removed from membranes into vesicles | Less water is reabsorbed; larger-volume dilute urine |
Changing membrane aquaporin number switches permeability rapidly without rebuilding the collecting duct, closing a negative-feedback loop.
During dehydration, increased ADH inserts more aquaporins, so water leaves the collecting duct by osmosis and blood osmotic concentration moves back toward its set point.
ADH changes permeability but does not create the medullary gradient; the loop of Henle establishes the gradient that makes water reabsorption possible.
This objective is assessed through structured response, commonly using Describe / Explain / Identify.
Describe / Explain / Identify / State / Outline
Build the answer around this relationship: High blood solute concentration stimulates ADH release.
Representative question
Explain the hormonal control of osmoregulation in the kidney by negative feedback.
HL D3.3 adds kidney and circulation mechanisms. The route is still feedback logic: nephrons filter and reabsorb, the loop of Henle builds a gradient, ADH changes collecting duct permeability, and blood vessels redistribute flow according to activity.
HL homeostasis transfer is about structure-function precision. In kidney answers, say where filtration, reabsorption, salt pumping, water movement, ADH, and aquaporins happen. In blood-flow answers, say which vessels dilate or constrict and how activity changes tissue demand.
