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Question #45774
The Question
A patient diagnosed with Myasthenia Gravis exhibits severe skeletal muscle fatigue and paralysis. Based on the mechanism of this autoimmune disorder, all of the following physiological statements accurately describe the state of their excitation-contraction coupling during an attempted voluntary movement, EXCEPT:
Options
- A.
Autoantibodies competitively block acetylcholine receptors at the neuromuscular junction, preventing sarcolemma depolarization.
- B.
The central nervous system fails to generate and propagate motor action potentials down the somatic motor neurons to the synaptic knob.
- C.
The sarcoplasmic reticulum retains its stored Ca2+ ions due to the absence of an action potential propagating down the T-tubules.
- D.
The active binding sites for myosin on the actin filaments remain masked by the troponin complex despite conscious effort to move.
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
Acetylcholine_Receptors|Skeletal_Muscle|Autoimmunity_Principles
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Distinguishing between pre-synaptic (motor neuron/CNS) and post-synaptic (sarcolemma) defects.
A common misconception among students is equating 'paralysis' or 'failure to contract' with an absence of the initial nerve signal.
In Myasthenia Gravis, the CNS fires normally and neurotransmitters are released, but the signal-transduction cascade fails exclusively at the receptor level.
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 |