The physical act of moving air into and out of the lungs is called:

• A. oxygenation
• B. diffusion
• C. ventilation
• D. respiration

Answer: (C)

Ventilation is the mechanical process of moving air into and out of the lungs. It happens when the diaphragm and chest muscles change the volume of the thoracic cavity, creating pressure gradients that pull air in during inspiration and push air out during expiration. This focuses on the physical act of air movement. Oxygenation refers to blood becoming oxygenated as a result of gas exchange, diffusion is the movement of gas molecules across the alveolar-capillary membranes, and respiration can refer to gas exchange or cellular energy production. In this context, the act of moving air itself is ventilation.