What describes the physical movement of air in and out of the lungs?

• A. Inspiration
• B. Expiration
• C. Ventilation
• D. Respiration

Answer: (C)

The physical movement of air in and out of the lungs is best described by the term "ventilation." This process encompasses both the inhalation of fresh air (inspiration) into the lungs and the exhalation of air (expiration) from the lungs. Ventilation refers to the overall mechanism by which air is exchanged in the respiratory system, allowing for gas exchange to occur in the alveoli where oxygen is taken up into the blood and carbon dioxide is eliminated.

Though inspiration and expiration are components of ventilation, they refer to the specific actions of inhaling and exhaling, respectively. Respiration, on the other hand, generally refers to the entire process of gas exchange that includes both ventilation and the cellular use of oxygen, making it a broader term. Therefore, the most comprehensive term that captures the movement of air specifically is ventilation.