Answer: Reducing the duration of inspiration.
- A Increasing the duration of inspiration
- B Reducing the duration of inspiration
- C Blocking the medullary rhythm centre
- D Stimulating surfactant secretion
Correct answer: B. Reducing the duration of inspiration
Explanation: The pneumotaxic centre of the pons can moderate the inspiratory signals from the medulla, reducing the duration of inspiration and altering the breathing rate.
The S-shaped (sigmoid) curve reflects cooperative binding between Hb's four O₂ sites; the Bohr effect shifts the whole curve to the right under conditions found in actively respiring tissue (more CO₂, more acid, more heat), making haemoglobin release oxygen more readily exactly where it's needed.
Concept context
The mechanics of breathing, lung volumes, gas transport in blood, the Bohr effect, and respiratory regulation.