How does antidiuretic hormone (ADH) in the blood influence water output in the body?

• A. ADH decreases water reabsorption in the kidneys, increasing water output.
• B. ADH increases urine production by promoting sodium excretion.
• C. ADH has no effect on water reabsorption in the kidneys.
• D. ADH increases water reabsorption in the kidneys, reducing water output.

Answer: (D)

Verified step by step guidance

1. Understand the role of antidiuretic hormone (ADH) in the body. ADH is a hormone that helps regulate water balance by influencing the kidneys.
2. Recognize that ADH primarily acts on the kidneys to increase water reabsorption. This means that when ADH levels are high, the kidneys reabsorb more water from the urine back into the bloodstream.
3. Consider the physiological effect of increased water reabsorption. When more water is reabsorbed, less water is excreted as urine, effectively reducing water output from the body.
4. Clarify the misconception that ADH decreases water reabsorption or increases urine production. In fact, ADH does the opposite by promoting water retention and reducing urine volume.
5. Conclude that the correct understanding of ADH's function is that it increases water reabsorption in the kidneys, thereby reducing water output and helping maintain hydration and electrolyte balance.