Question

A person can hold his breath longer if he gradually exhales than if he keeps his lungs fully expanded. This phenomenon is due to the fact that ___________________________.

• A. the concentration of CO${}_2$ in the blood decreases, lessening the excitatory input to the carotid bodies
• B. he is then using less 0${}_2$, as his thoracic muscles are not working as hard
• C. stretch receptors in his lungs are then not firing as much thus lessening the excitatory input to the expiratory centres
• D. he is preventing the pressure in his lungs from increasing too much

Answer 1

Answer: (C)

stretch receptors in his lungs are then not firing as much thus lessening the excitatory input to the expiratory centres

As we store air for long time inhaling, keeping the lungs expanded, this increases the concentration of co2 in our body that forces the lungs to further release the stored air inside the lungs previously. Hence, our body feels favored in exhaling the air slowly than keeping it longer.