Textbook Question
The distal convoluted tubule is an important site for
(a) Active secretion of ions
(b) Active secretion of acids and other materials
(c) Selective reabsorption of sodium ions from the tubular fluid
(d) All of these
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25. The Urinary System
Renal Physiology Step 2: Tubular Reabsorption
Multiple Choice
Predict what would happen if the tubule wall of the descending limb suddenly lost all its aquaporins.
A
More reabsorption would occur in the nephron loop.
B
Urine would be higher in volume & more dilute.
C
Urine would be lower in volume and more concentrated.
D
Urine would have the same volume but be more concentrated.
Verified step by step guidance1
Understand the role of aquaporins: Aquaporins are water channels that facilitate the reabsorption of water in the nephron, particularly in the descending limb of the loop of Henle.
Consider the function of the descending limb: Normally, the descending limb is permeable to water due to aquaporins, allowing water to be reabsorbed into the surrounding interstitial fluid, concentrating the urine.
Predict the impact of losing aquaporins: If the descending limb loses all its aquaporins, it becomes impermeable to water, preventing water reabsorption and leading to more water remaining in the tubule.
Analyze the effect on urine volume and concentration: With less water reabsorbed, the urine would be higher in volume and more dilute, as the concentration of solutes would be lower due to the increased water content.
Conclude the physiological outcome: The absence of aquaporins in the descending limb would result in urine that is higher in volume and more dilute, as the nephron's ability to concentrate urine is compromised.
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