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Question #45432
The Question
In ecosystems, phosphorus is primarily found in sedimentary rock reservoirs, but in the human body, its homeostasis is tightly coupled with calcium. In a patient with chronic renal failure, severe hyperphosphatemia (high serum phosphate) often leads to secondary hyperparathyroidism and bone demineralization. Which of the following statements regarding the physiological compensation in this state is INCORRECT?
Options
- A.
Excess serum phosphate disrupts the calcium-phosphate solubility product by binding free ionized calcium, which triggers the release of Parathyroid Hormone (PTH).
- B.
Elevated serum phosphate suppresses renal 1-alpha-hydroxylase, reducing the formation of active Vitamin D and decreasing intestinal calcium absorption.
- C.
Chronic elevation of PTH stimulates osteoclastic activity to restore serum calcium, leading to systemic bone demineralization.
- D.
Compensatory secretion of Atrial Natriuretic Factor (ANF) is directly triggered by hyperphosphatemia to inhibit the RAAS pathway and increase renal calcium reabsorption.
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Correct Answer
Step-by-Step Solution
Explanation
How the Examiner Thinks
Evolutionary_Exception
Tackle problems where standard rules evolve or change based on specific environmental constraints.
Concepts Behind This Question
Calcium_Phosphate_Homeostasis|Renal_Excretion|Phosphorus_Cycling
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Distinguishing between hemodynamic triggers and ionic triggers for renal-acting hormones.
The trap relies on the student assuming that because ANF acts on the kidneys to alter solute excretion, it might be a compensatory mechanism for any ionic imbalance (like hyperphosphatemia).
However, ANF is strictly volume/pressure-dependent (atrial stretch), whereas PTH and Calcitonin are ion-dependent.
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Chemical Coordination and Integration - Class 11 |
| Concept | Calcium Homeostasis |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |