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Question #46186
The Question
In reptiles (excluding crocodiles), the heart pumps out mixed blood due to incomplete double circulation. If a terrestrial snake experiences severe systemic hypotension, it rapidly enters a state of bradypnea (reduced breathing rate) and metabolic depression. Which of the following best explains the physiological basis for this rapid decompensation?
Options
- A.
Hypotension decreases the pulmonary transit time, preventing the oxygenation of blood in the right atrium, leading to severe systemic hypoxia.
- B.
The single ventricle inherently supplies blood with a lower pO2 to systemic tissues; hypotension critically reduces the tissue-level diffusion gradient, necessitating a drop in metabolic demand.
- C.
The absence of a true pulmonary circuit in reptiles forces the skin to act as the primary respiratory organ, which fails during low systemic blood pressure.
- D.
Hypotension causes the interatrial septum to fail, leading to complete mixing of blood before it reaches the ventricle, thereby halting cellular respiration.
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
Reptilian Heart Anatomy|Hypertension vs Hypotension Logic|Partial Pressure Gradient Logic
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Students often memorize 'incomplete double circulation' as merely 'mixed blood in the ventricle' without applying it to gas exchange dynamics (partial pressure gradients).
The trap lies in failing to link the structural limitation (single ventricle) to its functional vulnerability (lower systemic pO2) during physiological stress like hypotension, where the pressure-dependent diffusion of oxygen is severely compromised.
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Animal Kingdom - Class 11 |
| Concept | Reptilian Heart Anatomy |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |