Before You Begin
Question #46380
The Question
During severe coronary ischemia, a patient develops fatal ventricular fibrillation despite having an intact autonomic neural supply to the heart. Which of the following best explains the primary cellular mechanism responsible for this arrhythmia?
Options
- A.
ATP depletion halts the Na+/K+ ATPase pump, causing intracellular K+ to leak out, leading to extracellular hyperkalemia and partial depolarization of the sarcolemma.
- B.
Hypoxia directly stimulates the cardio-inhibitory center in the medulla oblongata, causing excessive acetylcholine release that hyperpolarizes the SA node.
- C.
Ischemia causes a rapid efflux of Ca2+ into the extracellular space, permanently blocking the plateau phase of the ventricular action potential.
- D.
The lack of oxygen forces the nodal tissue to switch to anaerobic respiration, generating lactic acid that physically severs the Bundle of His.
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
SA Node|K+ leakage|Myocardial infarction
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Students often assume cardiac arrhythmias are strictly due to neural (ANS) or nodal structural failures.
This question tests the synthesis of cellular metabolism (ATP production) with neurophysiology (Na+/K+ pump and RMP).
The common misconception is failing to recognize that even with intact neural signals, the effector tissue (myocardium) cannot maintain its rhythm if its fundamental ionic gradient collapses due to metabolic starvation.
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Body Fluids and Circulation - Class 11 |
| Concept | Coronary Circulation Specifics |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |