Before You Begin
Question #47424
The Question
A mountaineer exposed to extreme cold stress exhibits a severe loss of coordinated motor movements. Based on the principles of enzyme kinetics and neural conduction, how does severe cold specifically disrupt saltatory conduction in myelinated motor neurons?
Options
- A.
Decreased Na+/K+ ATPase activity prolongs the refractory period by delaying the restoration of ionic concentration gradients at the Nodes of Ranvier.
- B.
Reduced kinetic energy prevents the opening of voltage-gated Na+ channels, completely blocking the depolarization phase at the internodes.
- C.
Thermal inhibition of the myelin sheath increases ion leakage, converting rapid saltatory conduction into slow continuous conduction.
- D.
Cold stress accelerates the active transport of K+ ions out of the axoplasm, leading to a state of permanent hyperpolarization at the nodes.
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
Na+/K+_ATPase|Action_Potential_Threshold|Thermal_Tolerance_Ranges
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Students often fail to distinguish between the passive processes of an action potential (depolarization via voltage-gated channels) and the active process of restoring the concentration gradient (Na+/K+ pump).
The trap relies on recognizing that temperature drops drastically inhibit active, enzyme-driven processes (ATPases) compared to passive diffusion, leading to prolonged refractory periods and uncoordinated signal transmission.
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 |