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Question #47423
The Question
Tetrodotoxin (TTX) is a potent neurotoxin that physically occludes the extracellular pore of specific ion channels. If a myelinated somatic motor neuron is exposed to a high dose of TTX, which of the following represents the most accurate physiological outcome?
Options
- A.
The resting membrane potential collapses rapidly due to the direct inhibition of the Na+/K+ ATPase pump.
- B.
Saltatory conduction is halted because the threshold stimulus fails to trigger a rapid influx of Na+ at the Nodes of Ranvier.
- C.
Repolarization is indefinitely delayed, leading to a prolonged absolute refractory period due to K+ channel blockade.
- D.
The action potential propagates continuously rather than in a jumping manner due to the degradation of the myelin sheath.
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
Voltage_Gated_Na_Channels|Nodes_of_Ranvier|Neurotransmission
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Distinguishing the specific roles of different membrane proteins (voltage-gated Na+ channels vs.
Na+/K+ pump) in nerve impulse conduction.
The trap relies on the common misconception that all neurotoxins cause continuous depolarization (tetanus) or destroy structural integrity, whereas TTX causes flaccid paralysis by silencing the electrical signal while leaving the resting membrane potential and structural integrity intact.
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Neural Control and Coordination - Class 11 |
| Concept | Saltatory Conduction Nodes |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |