What is the passive component of respiration?

The correct answer is expiration, which is considered the passive component of respiration. During expiration, the diaphragm and intercostal muscles relax, allowing the elastic recoil of the lungs and the thoracic cavity to expel air from the lungs. This process does not require active muscle contraction; instead, it relies on the natural elasticity of the respiratory system.

In contrast, inspiration is an active process that involves the contraction of the diaphragm and other muscles to facilitate the intake of air. Ventilation refers to the overall process of moving air in and out of the lungs, encompassing both inspiration and expiration. Diffusion, while a crucial part of gas exchange, describes the movement of gases (such as oxygen and carbon dioxide) across the alveolar membrane and is not a component of the mechanical process of respiration itself.