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ADH control of urine concentration
The kidneys have an important role in homeostasis.
Explain how ADH affects the production and concentration of urine by the kidneys.
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Marking points
- 1 Links higher ADH to greater water permeability/reabsorption.
- 2 Locates the water reabsorption in the kidney tubules.
- 3 Explains that the urine becomes more concentrated.
- 4 Explains that a smaller volume of urine is produced.
Full-mark answer
A high ADH level makes the kidney tubules more permeable to water, so more water is reabsorbed from the tubules into the blood. This produces a smaller volume of more concentrated urine. Low ADH has the opposite effect.
Why this answer loses marks
ADH adds water to the urine.
High ADH increases water reabsorption from the tubules, so link it to both urine volume and concentration.