Is quiet breathing primarily a passive or active process during expiration?

Is quiet breathing primarily a passive or active process during expiration?

• A. Active
• B. Passive
• C. Both active and passive
• D. None of the above

Answer: (B)

During quiet breathing, particularly during expiration, the process is primarily passive. This is mainly due to the relaxation of the diaphragm and the elastic recoil of the lung tissue. When we inhale, the diaphragm contracts and the thoracic cavity expands, creating a negative pressure that draws air into the lungs. However, during expiration, particularly when it is quiet and not forced, the diaphragm relaxes, and the thoracic cavity decreases in volume. This volume change allows air to be expelled from the lungs without muscle contraction. The elastic properties of the lungs and the chest wall facilitate this process, as they return to their resting positions after inhalation, expelling air out of the respiratory system. Therefore, quiet expiration does not require additional energy or muscular effort, marking it as a passive process in contrast to active expiration, which involves muscle contraction during vigorous breathing or exercise when expelling air forcefully.

During quiet breathing, particularly during expiration, the process is primarily passive. This is mainly due to the relaxation of the diaphragm and the elastic recoil of the lung tissue. When we inhale, the diaphragm contracts and the thoracic cavity expands, creating a negative pressure that draws air into the lungs. However, during expiration, particularly when it is quiet and not forced, the diaphragm relaxes, and the thoracic cavity decreases in volume. This volume change allows air to be expelled from the lungs without muscle contraction.

The elastic properties of the lungs and the chest wall facilitate this process, as they return to their resting positions after inhalation, expelling air out of the respiratory system. Therefore, quiet expiration does not require additional energy or muscular effort, marking it as a passive process in contrast to active expiration, which involves muscle contraction during vigorous breathing or exercise when expelling air forcefully.