What regulates urine volume?

What regulates urine volume?

• A. ADH, Aldosterone, ANP
• B. Only ADH
• C. Only Aldosterone
• D. Only ANP

Answer: (A)

Urine volume is governed by how much water the kidneys reabsorb, which is controlled by three hormones working together. ADH increases water reabsorption in the collecting ducts by triggering aquaporin channels, so more ADH makes urine volume smaller. Aldosterone raises sodium reabsorption in the distal tubule and collecting duct; since water follows salt, reabsorbing more Na+ also reduces urine volume. ANP promotes diuresis by increasing sodium and water excretion and by opposing the renin–angiotensin–aldosterone system, which further drives up urine production. Because each hormone shifts the balance between reabsorption and excretion in different ways, all three participate in regulating urine volume.

Urine volume is governed by how much water the kidneys reabsorb, which is controlled by three hormones working together. ADH increases water reabsorption in the collecting ducts by triggering aquaporin channels, so more ADH makes urine volume smaller. Aldosterone raises sodium reabsorption in the distal tubule and collecting duct; since water follows salt, reabsorbing more Na+ also reduces urine volume. ANP promotes diuresis by increasing sodium and water excretion and by opposing the renin–angiotensin–aldosterone system, which further drives up urine production. Because each hormone shifts the balance between reabsorption and excretion in different ways, all three participate in regulating urine volume.