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Question #45796
The Question
Atrial Natriuretic Factor (ANF) is secreted by the atrial wall in response to increased venous return and acts as a physiological antagonist to the Renin-Angiotensin-Aldosterone System (RAAS). If a pathological overproduction of ANF leads to severe hyponatremia (extreme depletion of extracellular sodium), which of the following represents the most likely indirect consequence on cardiac muscle dynamics?
Options
- A.
Enhanced extrusion of calcium via the Na+/Ca2+ exchanger, leading to a weakened force of contraction.
- B.
Diminished transmembrane sodium gradient, impairing the Na+/Ca2+ exchanger and resulting in intracellular calcium overload.
- C.
Increased obligatory reabsorption of sodium in the proximal convoluted tubule, directly triggering massive calcium influx.
- D.
Direct inhibition of voltage-gated L-type calcium channels, preventing the plateau phase of the cardiac action potential.
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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
Myocardium|Extracellular_Ca_Entry|ANF
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Students must link the macroscopic endocrine function of ANF (sodium excretion/antagonizing RAAS) to the microscopic cellular mechanism of cardiac muscle relaxation.
The trap lies in failing to recognize that secondary active transport (like the Na+/Ca2+ exchanger) is strictly dependent on the primary concentration gradient of sodium; altering extracellular sodium fundamentally disrupts intracellular calcium homeostasis.
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Locomotion and Movement - Class 11 |
| Concept | Calcium Dynamics |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |