How does air pressure difference relate to airflow in the respiratory system?

• A. Increases volume
• B. Reduces compliance
• C. Affects gas exchange
• D. Drives airflow

Answer: (D)

Air pressure difference is a fundamental principle that drives airflow within the respiratory system. When the pressure inside the lungs (intrapulmonary pressure) is different from the atmospheric pressure outside, air moves from an area of higher pressure to an area of lower pressure.

During inhalation, the diaphragm and intercostal muscles contract, expanding the thoracic cavity and decreasing intrapulmonary pressure relative to atmospheric pressure. This negative pressure allows air to flow into the lungs. Conversely, during exhalation, these muscles relax, causing the thoracic cavity to decrease in volume, leading to an increase in intrapulmonary pressure, which forces air out of the lungs.

This relationship between pressure differences and airflow is critical for efficient breathing and effective gas exchange, as it ensures that oxygen can be brought into the body and carbon dioxide can be expelled. Understanding this pressure-driven mechanism is crucial for grasping how ventilation works and how various factors can affect respiratory function.