Question 3c
Explain why the person produced so much urine after drinking the litre of water. [4]
Answer:
The large volume of urine produced after drinking water can be explained by:
- Increased Blood Water Potential: Drinking a large volume of water increases the water potential of the blood, diluting the blood plasma.
- Reduced ADH Secretion: The hypothalamus detects the higher water potential and reduces the release of antidiuretic hormone (ADH) from the posterior pituitary gland.
- Decreased Water Reabsorption: Lower levels of ADH make the walls of the collecting ducts in the kidneys less permeable to water, resulting in less water reabsorption.
- Increased Urine Output: As a result, more water remains in the filtrate, leading to a greater volume of dilute urine being excreted.