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Question #47469
The Question
Myasthenia gravis is an autoimmune disorder that affects the neuromuscular junction, leading to fatigue, weakening, and paralysis of skeletal muscle. During an attempted voluntary movement in a patient with this condition, which of the following physiological events is INCORRECTLY described?
Options
- A.
Voltage-gated calcium channels on the pre-synaptic membrane open normally upon arrival of an action potential.
- B.
Autoantibodies competitively bind to the specific receptors on the motor end plate, preventing neurotransmitter binding.
- C.
The primary cause of synaptic failure is the reduced exocytosis of acetylcholine from the pre-synaptic synaptic vesicles.
- D.
Failure of ligand-gated sodium channels to open on the sarcolemma prevents the generation of an end-plate potential.
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
Neurotransmitter Receptor Specificity|Autoimmunity Principles|Acetylcholine Receptors
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Distinguishing between pre-synaptic and post-synaptic defects in neuromuscular disorders.
Students often confuse the site of action in Myasthenia Gravis (post-synaptic receptor blockade) with pre-synaptic disorders where neurotransmitter release is impaired.
The trap relies on the assumption that 'synaptic failure' implies a lack of neurotransmitter release, whereas in this specific autoimmune condition, the release is perfectly normal but the reception is physically blocked.
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Neural Control and Coordination - Class 11 |
| Concept | Neurotransmitter Receptor Specificity |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |