Before You Begin
Question #45743
The Question
In a patient suffering from severe Diabetes Insipidus due to a complete deficiency of ADH (Vasopressin), the ability to maintain the high osmolarity (1200 mOsmL-1) of the inner medullary interstitium is significantly compromised. Which of the following is the primary physiological reason for this secondary collapse of the medullary hypertonicity gradient?
Options
- A.
Absence of ADH directly inhibits the active transport of NaCl from the thick ascending limb of Henle's loop into the interstitium.
- B.
Failure of facultative water reabsorption in the collecting duct prevents the concentration of urea, thereby reducing its passive diffusion into the medullary interstitium.
- C.
The collecting duct becomes completely impermeable to water, triggering the active secretion of urea into the vasa recta to compensate for the gradient loss.
- D.
Decreased water reabsorption in the distal convoluted tubule directly prevents the active transport of urea into the medullary interstitium.
Check Your Answer
Correct Answer
Step-by-Step Solution
Explanation
How the Examiner Thinks
Regulatory_Failure
Understand how NOT, EXCEPT, and logical constraints are used to manipulate exam results.
Concepts Behind This Question
Vasopressin|Collecting_Duct|Medullary_Interstitium
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Students often isolate the function of ADH strictly to 'water reabsorption via aquaporins' without synthesizing its secondary effect on the Counter-Current Mechanism.
The misconception is failing to realize that water extraction in the cortical/outer medullary collecting duct is an absolute prerequisite for concentrating urea, which must then passively diffuse into the inner medulla to maintain the hypertonic gradient.
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Excretory Products and Their Elimination - Class 11 |
| Concept | Urea Recycling |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |