# A person drinks a large volume of water on a hot day. Describe how the body responds to maintain water balance.

> Eduqas A-Level Biology — 3.7 Homeostasis and the kidney · Describe · 5 marks

> After drinking a large volume of water, the concentration of the blood plasma falls below normal levels.

## Mark scheme (5 marks)

1. The fall in blood plasma concentration / lower water concentration in blood is detected by the hypothalamus
2. Less ADH is released / secreted from the pituitary gland
3. The kidneys reabsorb less water back into the blood
4. More water passes out in the urine / urine becomes more dilute / larger volume of urine is produced
5. This returns blood plasma concentration back to normal / restores water balance (homeostasis)

## Related

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