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Question #45425
The Question
A patient exhibits a severe defect in the iodination of tyrosine residues within the thyroid follicles. During a prolonged fasting state, this patient is found to be highly susceptible to severe hypoglycemia. Which of the following best explains the physiological basis of this integrated metabolic failure?
Options
- A.
Absence of thyroxine prevents the direct conversion of liver glycogen into glucose by inhibiting the enzyme glycogen phosphorylase.
- B.
Reduced thyroxine levels lead to a decreased expression of beta-adrenergic receptors, blunting the glycogenolytic effect of catecholamines.
- C.
Elevated TSH levels competitively inhibit glucagon receptors on hepatocytes, preventing counter-regulatory glycogenolysis.
- D.
The lack of thyroid hormones directly stimulates pancreatic beta-cells to hypersecrete insulin, causing rapid cellular glucose uptake.
Check Your Answer
Correct Answer
Step-by-Step Solution
Explanation
How the Examiner Thinks
Comparative_Analysis
Sharpen your ability to evaluate multiple scenarios and distinguish between competing potential answers.
Concepts Behind This Question
Thyroxine|Metabolic_Rate|Insulin vs Glucagon Effects
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Students often memorize that thyroid hormones regulate carbohydrate metabolism but miss the integrated mechanism.
The trap is failing to recognize the 'permissive action' of thyroid hormones on catecholamine-induced glycogenolysis.
Distractors use plausible-sounding but physiologically incorrect mechanisms like direct enzyme inhibition or TSH receptor cross-reactivity.
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Chemical Coordination and Integration - Class 11 |
| Concept | Thyroid Hormone Synthesis |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |