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Question #45775
The Question
A patient exhibits sustained tachycardia due to a metabolic defect that abnormally prolongs the half-life of epinephrine in the bloodstream. The enhanced stimulatory signal from the SA node rapidly results in a synchronized, whole-ventricular contraction. Which of the following structural features of the cardiac tissue is primarily responsible for this synchronized response, and how does it functionally differentiate cardiac muscle from skeletal muscle?
Options
- A.
Intercalated discs containing gap junctions; they allow the cardiac muscle to act as a functional syncytium, whereas skeletal muscles require individual motor end-plate stimulation.
- B.
Abundant T-tubules; they allow rapid calcium influx from the extracellular fluid to synchronize contraction, whereas skeletal muscles rely solely on the sarcoplasmic reticulum.
- C.
Desmosomes in the intercalated discs; they provide electrical coupling between adjacent myocytes, whereas skeletal muscles lack cell-to-cell adhesion.
- D.
Autonomic innervation of every cardiac myocyte; it ensures simultaneous depolarization, whereas skeletal muscles are innervated by somatic motor neurons.
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
Gap_Junctions|Cardiac_Myocytes|Hormone_Half_life_Logic
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Distinguishing between the mechanical (desmosomes) and electrical (gap junctions) components of intercalated discs.
The trap relies on confusing the 'functional syncytium' organization of cardiac muscle with the 'motor unit' organization of skeletal muscle, and misattributing electrical coupling to desmosomes or direct whole-tissue autonomic innervation.
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Locomotion and Movement - Class 11 |
| Concept | Muscle Type Differentiation |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |