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Question #46362
The Question
A patient with a chronic endocrine disorder exhibits systemic calcium dysregulation, leading to a marked decrease in cytosolic calcium availability in the myocardium. This impairs excitation-contraction coupling, resulting in a reduced stroke volume. To maintain adequate cardiac output, a compensatory autonomic reflex is triggered. Which of the following best describes the immediate consequence of this compensatory mechanism on the temporal precision of the patient's cardiac cycle?
Options
- A.
The duration of ventricular systole is significantly prolonged to allow maximum ejection of the reduced stroke volume.
- B.
The duration of joint diastole is disproportionately shortened, leading to a decreased passive ventricular filling time.
- C.
The AV node increases its conduction delay to ensure complete atrial emptying before ventricular contraction begins.
- D.
The stroke volume is restored to normal by a compensatory increase in the end-systolic volume.
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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
Troponin|Sarcoplasmic Reticulum|Myocardial Contractility
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Students often understand the formula CO = HR x SV, but fail to synthesize the temporal consequences of compensatory tachycardia on the specific phases of the cardiac cycle.
A common misconception is that a 'weaker' heart will take longer to pump (prolonging systole), whereas the actual sympathetic compensatory reflex speeds up the heart rate, primarily sacrificing the diastolic filling period.
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Body Fluids and Circulation - Class 11 |
| Concept | Cardiac Cycle Temporal Precision |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |