Which statement best defines pulmonary ventilation?

Which statement best defines pulmonary ventilation?

• A. Gas exchange between alveoli and blood
• B. Movement of air in and out of the lungs, also known as breathing
• C. Transport of oxygen in the bloodstream
• D. Use of oxygen by cells to produce energy

Answer: (B)

Pulmonary ventilation is the mechanical movement of air into and out of the lungs, i.e., breathing. It relies on the diaphragm and intercostal muscles to create pressure changes: when the diaphragm contracts and the chest expands, air rushes into the lungs (inspiration) as intrapulmonary pressure falls below atmospheric pressure; when the muscles relax and the chest returns toward its resting size, air exits the lungs (expiration) as intrapulmonary pressure rises above atmospheric pressure. This air movement is the first step that makes gas exchange possible. The other statements describe later stages of respiration: gas exchange between alveoli and blood (external respiration), transport of oxygen in the bloodstream, and the cellular use of oxygen to produce energy.

Pulmonary ventilation is the mechanical movement of air into and out of the lungs, i.e., breathing. It relies on the diaphragm and intercostal muscles to create pressure changes: when the diaphragm contracts and the chest expands, air rushes into the lungs (inspiration) as intrapulmonary pressure falls below atmospheric pressure; when the muscles relax and the chest returns toward its resting size, air exits the lungs (expiration) as intrapulmonary pressure rises above atmospheric pressure. This air movement is the first step that makes gas exchange possible.

The other statements describe later stages of respiration: gas exchange between alveoli and blood (external respiration), transport of oxygen in the bloodstream, and the cellular use of oxygen to produce energy.