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Question #45792
The Question
A farmer exposed to an organophosphate pesticide exhibits severe muscle spasms followed by profound paralysis. Organophosphates irreversibly inhibit the enzyme acetylcholinesterase at the neuromuscular junction. Which of the following best explains the physiological state of the motor endplate during the paralytic phase?
Options
- A.
Failure of calcium ion release from the sarcoplasmic reticulum due to blocked T-tubules.
- B.
Persistent depolarization of the sarcolemma preventing the resetting of voltage-gated sodium channels.
- C.
Competitive antagonism of acetylcholine receptors on the post-synaptic membrane.
- D.
Exhaustion of synaptic vesicles in the presynaptic neuron leading to a failure of neurotransmitter exocytosis.
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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
Neuromuscular Junction Signal|Neurotransmitter Receptor Specificity|Reflex Arc Latency
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Students often confuse the mechanisms of different paralytic agents.
While Curare causes paralysis by blocking ACh receptors (preventing depolarization), Organophosphates cause paralysis by preventing ACh breakdown, leading to a 'depolarizing block' where the membrane is stuck in a depolarized, refractory state.
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Locomotion and Movement - Class 11 |
| Concept | Neuromuscular Junction Signal |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |