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Question #46868
The Question
In an experimental model, mammalian cardiac tissue subjected to extreme thermal stress develops severe re-entry arrhythmias. However, histological and biochemical analyses reveal that the individual myocytes maintain their structural integrity and the actin-myosin contractile apparatus remains fully functional. Which of the following best explains the primary mechanism behind this heat-induced arrhythmia?
Options
- A.
Destabilization of connexins and cadherins at the intercalated discs, leading to myocardial decoupling and disrupted electrical propagation.
- B.
Thermal degradation of the myelin sheath surrounding the Purkinje fibers, causing a delay in the ventricular depolarization wave.
- C.
Heat-induced conformational changes in the troponin complex, preventing calcium binding and unmasking of active sites.
- D.
Increased membrane fluidity of the Sinoatrial (SA) node, resulting in a uniform but accelerated generation of action potentials.
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
Intercalated Disc Function|Thermal Tolerance Ranges|Conducting System Sequence
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Students often assume that cardiac failure under stress is due to the contractile proteins (actin/myosin) or nervous supply.
The pivot is recognizing the structural-functional hierarchy in cardiac muscle: intercalated discs are the weakest link under thermal stress.
Their failure disrupts the syncytium, leading to arrhythmias before the myocyte itself structurally fails.
Common Misconception: Confusing the specialized conduction system of the heart (Purkinje fibers) with nervous tissue by assuming they possess myelin sheaths.
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Structural Organisation in Animals - Class 11 |
| Concept | Intercalated Disc Function |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |