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Question #46361
The Question
A high-altitude resident experiences chronic hypoxia, leading to an enhanced Bohr effect and increased chloride shift at the tissue level. To compensate, the juxtaglomerular cells release a specific hormone. How does the long-term action of this hormone ultimately alter the temporal precision of the cardiac cycle?
Options
- A.
It stimulates erythropoiesis, leading to polycythemia, which increases blood viscosity and afterload, thereby prolonging the ventricular ejection phase.
- B.
It stimulates renin release, which activates the RAAS pathway to increase blood volume and preload, thereby shortening the isovolumetric relaxation phase.
- C.
It increases the synthesis of carbonic anhydrase in RBCs, accelerating the Hamburger phenomenon and decreasing peripheral resistance, which shortens ventricular systole.
- D.
It promotes the maturation of erythrocytes, decreasing overall blood viscosity and reducing the afterload, which accelerates the opening of the semilunar valves.
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
Hemoglobin|Bicarbonate|Oxygen Dissociation Curve
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Students often isolate respiratory physiology (Chloride shift/Bohr effect), renal endocrinology (EPO), and cardiovascular hemodynamics (Cardiac cycle).
The trap lies in understanding that increased RBC production (erythropoiesis) directly alters the physical properties of blood (viscosity).
This mechanically forces the heart to adjust its systolic timing, as increased afterload prolongs the ejection phase.
Failing to link blood rheology to ventricular afterload leads to selecting incorrect compensatory mechanisms.
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Body Fluids and Circulation - Class 11 |
| Concept | Cardiac Cycle Temporal Precision |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |