# A patient has damage to their pituitary gland meaning it can no longer secrete ADH. Explain how this would affect the patient's urine and why this change in urine occurs.

> Eduqas A-Level Biology — 4.5 Homeostasis and the kidney · Explain · 5 marks

> ADH is a hormone secreted by the pituitary gland which increases water reabsorption in the kidney by making the kidney tubules more permeable to water.

## Mark scheme (5 marks)

1. The patient would produce a large volume of urine
2. The urine would be more dilute / less concentrated
3. Without ADH, the kidney tubules / collecting duct are less permeable to water
4. Less water is reabsorbed from the kidney tubules / collecting duct back into the blood
5. More water passes out of the body in the urine / blood water concentration falls / water balance is not maintained (homeostasis is disrupted)

## Key terms

- [ADH](https://www.gradenine.co.uk/glossary/adh)
- [pituitary gland](https://www.gradenine.co.uk/glossary/pituitary-gland)

## Related

- [Revision notes for Eduqas A-Level Biology](https://www.gradenine.co.uk/learn)
- [How to answer "Explain" questions](https://www.gradenine.co.uk/tools/command-word-cheatsheet)
- [Practice this with AI marking (free)](https://www.gradenine.co.uk/start)

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Source: [GradeNine](https://www.gradenine.co.uk/q/a-patient-has-damage-to-their-58985c56) · Published by Druglandscape Ltd.